| Age | Commit message (Collapse) | Author | Files | Lines |
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Combinatorial Kconfig is painfull. Withi this patch all below combination
build.
1)
2)
CONFIG_HMM_MIRROR=y
3)
CONFIG_DEVICE_PRIVATE=y
4)
CONFIG_DEVICE_PUBLIC=y
5)
CONFIG_HMM_MIRROR=y
CONFIG_DEVICE_PUBLIC=y
6)
CONFIG_HMM_MIRROR=y
CONFIG_DEVICE_PRIVATE=y
7)
CONFIG_DEVICE_PRIVATE=y
CONFIG_DEVICE_PUBLIC=y
8)
CONFIG_HMM_MIRROR=y
CONFIG_DEVICE_PRIVATE=y
CONFIG_DEVICE_PUBLIC=y
Link: http://lkml.kernel.org/r/20170826002149.20919-1-jglisse@redhat.com
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This moves all new code including new page migration helper behind kernel
Kconfig option so that there is no codee bloat for arch or user that do
not want to use HMM or any of its associated features.
arm allyesconfig (without all the patchset, then with and this patch):
text data bss dec hex filename
83721896 46511131 27582964 157815991 96814b7 ../without/vmlinux
83722364 46511131 27582964 157816459 968168b vmlinux
[jglisse@redhat.com: struct hmm is only use by HMM mirror functionality]
Link: http://lkml.kernel.org/r/20170825213133.27286-1-jglisse@redhat.com
[sfr@canb.auug.org.au: fix build (arm multi_v7_defconfig)]
Link: http://lkml.kernel.org/r/20170828181849.323ab81b@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170818032858.7447-1-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Unlike unaddressable memory, coherent device memory has a real resource
associated with it on the system (as CPU can address it). Add a new
helper to hotplug such memory within the HMM framework.
Link: http://lkml.kernel.org/r/20170817000548.32038-20-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Platform with advance system bus (like CAPI or CCIX) allow device memory
to be accessible from CPU in a cache coherent fashion. Add a new type of
ZONE_DEVICE to represent such memory. The use case are the same as for
the un-addressable device memory but without all the corners cases.
Link: http://lkml.kernel.org/r/20170817000548.32038-19-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This allows callers of migrate_vma() to allocate new page for empty CPU
page table entry (pte_none or back by zero page). This is only for
anonymous memory and it won't allow new page to be instanced if the
userfaultfd is armed.
This is useful to device driver that want to migrate a range of virtual
address and would rather allocate new memory than having to fault later
on.
Link: http://lkml.kernel.org/r/20170817000548.32038-18-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Allow to unmap and restore special swap entry of un-addressable
ZONE_DEVICE memory.
Link: http://lkml.kernel.org/r/20170817000548.32038-17-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Common case for migration of virtual address range is page are map only
once inside the vma in which migration is taking place. Because we
already walk the CPU page table for that range we can directly do the
unmap there and setup special migration swap entry.
Link: http://lkml.kernel.org/r/20170817000548.32038-16-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch add a new memory migration helpers, which migrate memory
backing a range of virtual address of a process to different memory (which
can be allocated through special allocator). It differs from numa
migration by working on a range of virtual address and thus by doing
migration in chunk that can be large enough to use DMA engine or special
copy offloading engine.
Expected users are any one with heterogeneous memory where different
memory have different characteristics (latency, bandwidth, ...). As an
example IBM platform with CAPI bus can make use of this feature to migrate
between regular memory and CAPI device memory. New CPU architecture with
a pool of high performance memory not manage as cache but presented as
regular memory (while being faster and with lower latency than DDR) will
also be prime user of this patch.
Migration to private device memory will be useful for device that have
large pool of such like GPU, NVidia plans to use HMM for that.
Link: http://lkml.kernel.org/r/20170817000548.32038-15-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Introduce a new migration mode that allow to offload the copy to a device
DMA engine. This changes the workflow of migration and not all
address_space migratepage callback can support this.
This is intended to be use by migrate_vma() which itself is use for thing
like HMM (see include/linux/hmm.h).
No additional per-filesystem migratepage testing is needed. I disables
MIGRATE_SYNC_NO_COPY in all problematic migratepage() callback and i
added comment in those to explain why (part of this patch). The commit
message is unclear it should say that any callback that wish to support
this new mode need to be aware of the difference in the migration flow
from other mode.
Some of these callbacks do extra locking while copying (aio, zsmalloc,
balloon, ...) and for DMA to be effective you want to copy multiple
pages in one DMA operations. But in the problematic case you can not
easily hold the extra lock accross multiple call to this callback.
Usual flow is:
For each page {
1 - lock page
2 - call migratepage() callback
3 - (extra locking in some migratepage() callback)
4 - migrate page state (freeze refcount, update page cache, buffer
head, ...)
5 - copy page
6 - (unlock any extra lock of migratepage() callback)
7 - return from migratepage() callback
8 - unlock page
}
The new mode MIGRATE_SYNC_NO_COPY:
1 - lock multiple pages
For each page {
2 - call migratepage() callback
3 - abort in all problematic migratepage() callback
4 - migrate page state (freeze refcount, update page cache, buffer
head, ...)
} // finished all calls to migratepage() callback
5 - DMA copy multiple pages
6 - unlock all the pages
To support MIGRATE_SYNC_NO_COPY in the problematic case we would need a
new callback migratepages() (for instance) that deals with multiple
pages in one transaction.
Because the problematic cases are not important for current usage I did
not wanted to complexify this patchset even more for no good reason.
Link: http://lkml.kernel.org/r/20170817000548.32038-14-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This introduce a dummy HMM device class so device driver can use it to
create hmm_device for the sole purpose of registering device memory. It
is useful to device driver that want to manage multiple physical device
memory under same struct device umbrella.
Link: http://lkml.kernel.org/r/20170817000548.32038-13-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This introduce a simple struct and associated helpers for device driver to
use when hotpluging un-addressable device memory as ZONE_DEVICE. It will
find a unuse physical address range and trigger memory hotplug for it
which allocates and initialize struct page for the device memory.
Device driver should use this helper during device initialization to
hotplug the device memory. It should only need to remove the memory once
the device is going offline (shutdown or hotremove). There should not be
any userspace API to hotplug memory expect maybe for host device driver to
allow to add more memory to a guest device driver.
Device's memory is manage by the device driver and HMM only provides
helpers to that effect.
Link: http://lkml.kernel.org/r/20170817000548.32038-12-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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HMM pages (private or public device pages) are ZONE_DEVICE page and thus
need special handling when it comes to lru or refcount. This patch make
sure that memcontrol properly handle those when it face them. Those pages
are use like regular pages in a process address space either as anonymous
page or as file back page. So from memcg point of view we want to handle
them like regular page for now at least.
Link: http://lkml.kernel.org/r/20170817000548.32038-11-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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HMM pages (private or public device pages) are ZONE_DEVICE page and
thus you can not use page->lru fields of those pages. This patch
re-arrange the uncharge to allow single page to be uncharge without
modifying the lru field of the struct page.
There is no change to memcontrol logic, it is the same as it was
before this patch.
Link: http://lkml.kernel.org/r/20170817000548.32038-10-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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A ZONE_DEVICE page that reach a refcount of 1 is free ie no longer have
any user. For device private pages this is important to catch and thus we
need to special case put_page() for this.
Link: http://lkml.kernel.org/r/20170817000548.32038-9-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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HMM (heterogeneous memory management) need struct page to support
migration from system main memory to device memory. Reasons for HMM and
migration to device memory is explained with HMM core patch.
This patch deals with device memory that is un-addressable memory (ie CPU
can not access it). Hence we do not want those struct page to be manage
like regular memory. That is why we extend ZONE_DEVICE to support
different types of memory.
A persistent memory type is define for existing user of ZONE_DEVICE and a
new device un-addressable type is added for the un-addressable memory
type. There is a clear separation between what is expected from each
memory type and existing user of ZONE_DEVICE are un-affected by new
requirement and new use of the un-addressable type. All specific code
path are protect with test against the memory type.
Because memory is un-addressable we use a new special swap type for when a
page is migrated to device memory (this reduces the number of maximum swap
file).
The main two additions beside memory type to ZONE_DEVICE is two callbacks.
First one, page_free() is call whenever page refcount reach 1 (which
means the page is free as ZONE_DEVICE page never reach a refcount of 0).
This allow device driver to manage its memory and associated struct page.
The second callback page_fault() happens when there is a CPU access to an
address that is back by a device page (which are un-addressable by the
CPU). This callback is responsible to migrate the page back to system
main memory. Device driver can not block migration back to system memory,
HMM make sure that such page can not be pin into device memory.
If device is in some error condition and can not migrate memory back then
a CPU page fault to device memory should end with SIGBUS.
[arnd@arndb.de: fix warning]
Link: http://lkml.kernel.org/r/20170823133213.712917-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20170817000548.32038-8-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
There are new users of memory hotplug emerging. Some of them require
different subset of arch_add_memory. There are some which only require
allocation of struct pages without mapping those pages to the kernel
address space. We currently have __add_pages for that purpose. But this
is rather lowlevel and not very suitable for the code outside of the
memory hotplug. E.g. x86_64 wants to update max_pfn which should be done
by the caller. Introduce add_pages() which should care about those
details if they are needed. Each architecture should define its
implementation and select CONFIG_ARCH_HAS_ADD_PAGES. All others use the
currently existing __add_pages.
Link: http://lkml.kernel.org/r/20170817000548.32038-7-jglisse@redhat.com
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This handles page fault on behalf of device driver, unlike
handle_mm_fault() it does not trigger migration back to system memory for
device memory.
Link: http://lkml.kernel.org/r/20170817000548.32038-6-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This does not use existing page table walker because we want to share
same code for our page fault handler.
Link: http://lkml.kernel.org/r/20170817000548.32038-5-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This is a heterogeneous memory management (HMM) process address space
mirroring. In a nutshell this provide an API to mirror process address
space on a device. This boils down to keeping CPU and device page table
synchronize (we assume that both device and CPU are cache coherent like
PCIe device can be).
This patch provide a simple API for device driver to achieve address space
mirroring thus avoiding each device driver to grow its own CPU page table
walker and its own CPU page table synchronization mechanism.
This is useful for NVidia GPU >= Pascal, Mellanox IB >= mlx5 and more
hardware in the future.
[jglisse@redhat.com: fix hmm for "mmu_notifier kill invalidate_page callback"]
Link: http://lkml.kernel.org/r/20170830231955.GD9445@redhat.com
Link: http://lkml.kernel.org/r/20170817000548.32038-4-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
HMM provides 3 separate types of functionality:
- Mirroring: synchronize CPU page table and device page table
- Device memory: allocating struct page for device memory
- Migration: migrating regular memory to device memory
This patch introduces some common helpers and definitions to all of
those 3 functionality.
Link: http://lkml.kernel.org/r/20170817000548.32038-3-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "HMM (Heterogeneous Memory Management)", v25.
Heterogeneous Memory Management (HMM) (description and justification)
Today device driver expose dedicated memory allocation API through their
device file, often relying on a combination of IOCTL and mmap calls.
The device can only access and use memory allocated through this API.
This effectively split the program address space into object allocated
for the device and useable by the device and other regular memory
(malloc, mmap of a file, share memory, â) only accessible by
CPU (or in a very limited way by a device by pinning memory).
Allowing different isolated component of a program to use a device thus
require duplication of the input data structure using device memory
allocator. This is reasonable for simple data structure (array, grid,
image, â) but this get extremely complex with advance data
structure (list, tree, graph, â) that rely on a web of memory
pointers. This is becoming a serious limitation on the kind of work
load that can be offloaded to device like GPU.
New industry standard like C++, OpenCL or CUDA are pushing to remove
this barrier. This require a shared address space between GPU device
and CPU so that GPU can access any memory of a process (while still
obeying memory protection like read only). This kind of feature is also
appearing in various other operating systems.
HMM is a set of helpers to facilitate several aspects of address space
sharing and device memory management. Unlike existing sharing mechanism
that rely on pining pages use by a device, HMM relies on mmu_notifier to
propagate CPU page table update to device page table.
Duplicating CPU page table is only one aspect necessary for efficiently
using device like GPU. GPU local memory have bandwidth in the TeraBytes/
second range but they are connected to main memory through a system bus
like PCIE that is limited to 32GigaBytes/second (PCIE 4.0 16x). Thus it
is necessary to allow migration of process memory from main system memory
to device memory. Issue is that on platform that only have PCIE the
device memory is not accessible by the CPU with the same properties as
main memory (cache coherency, atomic operations, ...).
To allow migration from main memory to device memory HMM provides a set of
helper to hotplug device memory as a new type of ZONE_DEVICE memory which
is un-addressable by CPU but still has struct page representing it. This
allow most of the core kernel logic that deals with a process memory to
stay oblivious of the peculiarity of device memory.
When page backing an address of a process is migrated to device memory the
CPU page table entry is set to a new specific swap entry. CPU access to
such address triggers a migration back to system memory, just like if the
page was swap on disk. HMM also blocks any one from pinning a ZONE_DEVICE
page so that it can always be migrated back to system memory if CPU access
it. Conversely HMM does not migrate to device memory any page that is pin
in system memory.
To allow efficient migration between device memory and main memory a new
migrate_vma() helpers is added with this patchset. It allows to leverage
device DMA engine to perform the copy operation.
This feature will be use by upstream driver like nouveau mlx5 and probably
other in the future (amdgpu is next suspect in line). We are actively
working on nouveau and mlx5 support. To test this patchset we also worked
with NVidia close source driver team, they have more resources than us to
test this kind of infrastructure and also a bigger and better userspace
eco-system with various real industry workload they can be use to test and
profile HMM.
The expected workload is a program builds a data set on the CPU (from
disk, from network, from sensors, â). Program uses GPU API (OpenCL,
CUDA, ...) to give hint on memory placement for the input data and also
for the output buffer. Program call GPU API to schedule a GPU job, this
happens using device driver specific ioctl. All this is hidden from
programmer point of view in case of C++ compiler that transparently
offload some part of a program to GPU. Program can keep doing other stuff
on the CPU while the GPU is crunching numbers.
It is expected that CPU will not access the same data set as the GPU while
GPU is working on it, but this is not mandatory. In fact we expect some
small memory object to be actively access by both GPU and CPU concurrently
as synchronization channel and/or for monitoring purposes. Such object
will stay in system memory and should not be bottlenecked by system bus
bandwidth (rare write and read access from both CPU and GPU).
As we are relying on device driver API, HMM does not introduce any new
syscall nor does it modify any existing ones. It does not change any
POSIX semantics or behaviors. For instance the child after a fork of a
process that is using HMM will not be impacted in anyway, nor is there any
data hazard between child COW or parent COW of memory that was migrated to
device prior to fork.
HMM assume a numbers of hardware features. Device must allow device page
table to be updated at any time (ie device job must be preemptable).
Device page table must provides memory protection such as read only.
Device must track write access (dirty bit). Device must have a minimum
granularity that match PAGE_SIZE (ie 4k).
Reviewer (just hint):
Patch 1 HMM documentation
Patch 2 introduce core infrastructure and definition of HMM, pretty
small patch and easy to review
Patch 3 introduce the mirror functionality of HMM, it relies on
mmu_notifier and thus someone familiar with that part would be
in better position to review
Patch 4 is an helper to snapshot CPU page table while synchronizing with
concurrent page table update. Understanding mmu_notifier makes
review easier.
Patch 5 is mostly a wrapper around handle_mm_fault()
Patch 6 add new add_pages() helper to avoid modifying each arch memory
hot plug function
Patch 7 add a new memory type for ZONE_DEVICE and also add all the logic
in various core mm to support this new type. Dan Williams and
any core mm contributor are best people to review each half of
this patchset
Patch 8 special case HMM ZONE_DEVICE pages inside put_page() Kirill and
Dan Williams are best person to review this
Patch 9 allow to uncharge a page from memory group without using the lru
list field of struct page (best reviewer: Johannes Weiner or
Vladimir Davydov or Michal Hocko)
Patch 10 Add support to uncharge ZONE_DEVICE page from a memory cgroup (best
reviewer: Johannes Weiner or Vladimir Davydov or Michal Hocko)
Patch 11 add helper to hotplug un-addressable device memory as new type
of ZONE_DEVICE memory (new type introducted in patch 3 of this
serie). This is boiler plate code around memory hotplug and it
also pick a free range of physical address for the device memory.
Note that the physical address do not point to anything (at least
as far as the kernel knows).
Patch 12 introduce a new hmm_device class as an helper for device driver
that want to expose multiple device memory under a common fake
device driver. This is usefull for multi-gpu configuration.
Anyone familiar with device driver infrastructure can review
this. Boiler plate code really.
Patch 13 add a new migrate mode. Any one familiar with page migration is
welcome to review.
Patch 14 introduce a new migration helper (migrate_vma()) that allow to
migrate a range of virtual address of a process using device DMA
engine to perform the copy. It is not limited to do copy from and
to device but can also do copy between any kind of source and
destination memory. Again anyone familiar with migration code
should be able to verify the logic.
Patch 15 optimize the new migrate_vma() by unmapping pages while we are
collecting them. This can be review by any mm folks.
Patch 16 add unaddressable memory migration to helper introduced in patch
7, this can be review by anyone familiar with migration code
Patch 17 add a feature that allow device to allocate non-present page on
the GPU when migrating a range of address to device memory. This
is an helper for device driver to avoid having to first allocate
system memory before migration to device memory
Patch 18 add a new kind of ZONE_DEVICE memory for cache coherent device
memory (CDM)
Patch 19 add an helper to hotplug CDM memory
Previous patchset posting :
v1 http://lwn.net/Articles/597289/
v2 https://lkml.org/lkml/2014/6/12/559
v3 https://lkml.org/lkml/2014/6/13/633
v4 https://lkml.org/lkml/2014/8/29/423
v5 https://lkml.org/lkml/2014/11/3/759
v6 http://lwn.net/Articles/619737/
v7 http://lwn.net/Articles/627316/
v8 https://lwn.net/Articles/645515/
v9 https://lwn.net/Articles/651553/
v10 https://lwn.net/Articles/654430/
v11 http://www.gossamer-threads.com/lists/linux/kernel/2286424
v12 http://www.kernelhub.org/?msg=972982&p=2
v13 https://lwn.net/Articles/706856/
v14 https://lkml.org/lkml/2016/12/8/344
v15 http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1304107.html
v16 http://www.spinics.net/lists/linux-mm/msg119814.html
v17 https://lkml.org/lkml/2017/1/27/847
v18 https://lkml.org/lkml/2017/3/16/596
v19 https://lkml.org/lkml/2017/4/5/831
v20 https://lwn.net/Articles/720715/
v21 https://lkml.org/lkml/2017/4/24/747
v22 http://lkml.iu.edu/hypermail/linux/kernel/1705.2/05176.html
v23 https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1404788.html
v24 https://lwn.net/Articles/726691/
This patch (of 19):
This adds documentation for HMM (Heterogeneous Memory Management). It
presents the motivation behind it, the features necessary for it to be
useful and and gives an overview of how this is implemented.
Link: http://lkml.kernel.org/r/20170817000548.32038-2-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This patch enables thp migration for memory hotremove.
Link: http://lkml.kernel.org/r/20170717193955.20207-11-zi.yan@sent.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This patch enables thp migration for move_pages(2).
Link: http://lkml.kernel.org/r/20170717193955.20207-10-zi.yan@sent.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This patch enables thp migration for mbind(2) and migrate_pages(2).
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Soft dirty bit is designed to keep tracked over page migration. This
patch makes it work in the same manner for thp migration too.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
When THP migration is being used, memory management code needs to handle
pmd migration entries properly. This patch uses !pmd_present() or
is_swap_pmd() (depending on whether pmd_none() needs separate code or
not) to check pmd migration entries at the places where a pmd entry is
present.
Since pmd-related code uses split_huge_page(), split_huge_pmd(),
pmd_trans_huge(), pmd_trans_unstable(), or
pmd_none_or_trans_huge_or_clear_bad(), this patch:
1. adds pmd migration entry split code in split_huge_pmd(),
2. takes care of pmd migration entries whenever pmd_trans_huge() is present,
3. makes pmd_none_or_trans_huge_or_clear_bad() pmd migration entry aware.
Since split_huge_page() uses split_huge_pmd() and pmd_trans_unstable()
is equivalent to pmd_none_or_trans_huge_or_clear_bad(), we do not change
them.
Until this commit, a pmd entry should be:
1. pointing to a pte page,
2. is_swap_pmd(),
3. pmd_trans_huge(),
4. pmd_devmap(), or
5. pmd_none().
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Add thp migration's core code, including conversions between a PMD entry
and a swap entry, setting PMD migration entry, removing PMD migration
entry, and waiting on PMD migration entries.
This patch makes it possible to support thp migration. If you fail to
allocate a destination page as a thp, you just split the source thp as
we do now, and then enter the normal page migration. If you succeed to
allocate destination thp, you enter thp migration. Subsequent patches
actually enable thp migration for each caller of page migration by
allowing its get_new_page() callback to allocate thps.
[zi.yan@cs.rutgers.edu: fix gcc-4.9.0 -Wmissing-braces warning]
Link: http://lkml.kernel.org/r/A0ABA698-7486-46C3-B209-E95A9048B22C@cs.rutgers.edu
[akpm@linux-foundation.org: fix x86_64 allnoconfig warning]
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Introduce CONFIG_ARCH_ENABLE_THP_MIGRATION to limit thp migration
functionality to x86_64, which should be safer at the first step.
Link: http://lkml.kernel.org/r/20170717193955.20207-5-zi.yan@sent.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Reviewed-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
TTU_MIGRATION is used to convert pte into migration entry until thp
split completes. This behavior conflicts with thp migration added later
patches, so let's introduce a new TTU flag specifically for freezing.
try_to_unmap() is used both for thp split (via freeze_page()) and page
migration (via __unmap_and_move()). In freeze_page(), ttu_flag given
for head page is like below (assuming anonymous thp):
(TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED | \
TTU_MIGRATION | TTU_SPLIT_HUGE_PMD)
and ttu_flag given for tail pages is:
(TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | TTU_RMAP_LOCKED | \
TTU_MIGRATION)
__unmap_and_move() calls try_to_unmap() with ttu_flag:
(TTU_MIGRATION | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS)
Now I'm trying to insert a branch for thp migration at the top of
try_to_unmap_one() like below
static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
unsigned long address, void *arg)
{
...
/* PMD-mapped THP migration entry */
if (!pvmw.pte && (flags & TTU_MIGRATION)) {
if (!PageAnon(page))
continue;
set_pmd_migration_entry(&pvmw, page);
continue;
}
...
}
so try_to_unmap() for tail pages called by thp split can go into thp
migration code path (which converts *pmd* into migration entry), while
the expectation is to freeze thp (which converts *pte* into migration
entry.)
I detected this failure as a "bad page state" error in a testcase where
split_huge_page() is called from queue_pages_pte_range().
Link: http://lkml.kernel.org/r/20170717193955.20207-4-zi.yan@sent.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
_PAGE_PSE is used to distinguish between a truly non-present
(_PAGE_PRESENT=0) PMD, and a PMD which is undergoing a THP split and
should be treated as present.
But _PAGE_SWP_SOFT_DIRTY currently uses the _PAGE_PSE bit, which would
cause confusion between one of those PMDs undergoing a THP split, and a
soft-dirty PMD. Dropping _PAGE_PSE check in pmd_present() does not work
well, because it can hurt optimization of tlb handling in thp split.
Thus, we need to move the bit.
In the current kernel, bits 1-4 are not used in non-present format since
commit 00839ee3b299 ("x86/mm: Move swap offset/type up in PTE to work
around erratum"). So let's move _PAGE_SWP_SOFT_DIRTY to bit 1. Bit 7
is used as reserved (always clear), so please don't use it for other
purpose.
Link: http://lkml.kernel.org/r/20170717193955.20207-3-zi.yan@sent.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "mm: page migration enhancement for thp", v9.
Motivations:
1. THP migration becomes important in the upcoming heterogeneous memory
systems. As David Nellans from NVIDIA pointed out from other threads
(http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1349227.html),
future GPUs or other accelerators will have their memory managed by
operating systems. Moving data into and out of these memory nodes
efficiently is critical to applications that use GPUs or other
accelerators. Existing page migration only supports base pages, which
has a very low memory bandwidth utilization. My experiments (see
below) show THP migration can migrate pages more efficiently.
2. Base page migration vs THP migration throughput.
Here are cross-socket page migration results from calling
move_pages() syscall:
In x86_64, a Intel two-socket E5-2640v3 box,
- single 4KB base page migration takes 62.47 us, using 0.06 GB/s BW,
- single 2MB THP migration takes 658.54 us, using 2.97 GB/s BW,
- 512 4KB base page migration takes 1987.38 us, using 0.98 GB/s BW.
In ppc64, a two-socket Power8 box,
- single 64KB base page migration takes 49.3 us, using 1.24 GB/s BW,
- single 16MB THP migration takes 2202.17 us, using 7.10 GB/s BW,
- 256 64KB base page migration takes 2543.65 us, using 6.14 GB/s BW.
THP migration can give us 3x and 1.15x throughput over base page
migration in x86_64 and ppc64 respectivley.
You can test it out by using the code here:
https://github.com/x-y-z/thp-migration-bench
3. Existing page migration splits THP before migration and cannot
guarantee the migrated pages are still contiguous. Contiguity is
always what GPUs and accelerators look for. Without THP migration,
khugepaged needs to do extra work to reassemble the migrated pages
back to THPs.
This patch (of 10):
Introduce a separate check routine related to MPOL_MF_INVERT flag. This
patch just does cleanup, no behavioral change.
Link: http://lkml.kernel.org/r/20170717193955.20207-2-zi.yan@sent.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The fix in the parent made me look at that function, and react to how
illogical and illegible the array initializer was.
Use named array indexes to make it clearer what is going on, and make
the initializer not depend silently on the exact index numbers.
[ The initializer now also shows an odd inconsistency in the naming:
note the IWCM vs IWPM.. - Linus ]
Cc: Leon Romanovsky <leonro@mellanox.com>
Cc: Doug Ledford <dledford@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The netlink message sent with type == 0, which doesn't have any client
behind it, caused to the overflow in max_num_ops array.
Fix it by declaring zero number of ops for the first client.
Fixes: c9901724a2f1 ("RDMA/netlink: Remove netlink clients infrastructure")
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Currently, aio-nr is incremented in steps of 'num_possible_cpus() * 8'
for io_setup(nr_events, ..) with 'nr_events < num_possible_cpus() * 4':
ioctx_alloc()
...
nr_events = max(nr_events, num_possible_cpus() * 4);
nr_events *= 2;
...
ctx->max_reqs = nr_events;
...
aio_nr += ctx->max_reqs;
....
This limits the number of aio contexts actually available to much less
than aio-max-nr, and is increasingly worse with greater number of CPUs.
For example, with 64 CPUs, only 256 aio contexts are actually available
(with aio-max-nr = 65536) because the increment is 512 in that scenario.
Note: 65536 [max aio contexts] / (64*4*2) [increment per aio context]
is 128, but make it 256 (double) as counting against 'aio-max-nr * 2':
ioctx_alloc()
...
if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
...
goto err_ctx;
...
This patch uses the original value of nr_events (from userspace) to
increment aio-nr and count against aio-max-nr, which resolves those.
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Reported-by: Lekshmi C. Pillai <lekshmi.cpillai@in.ibm.com>
Tested-by: Lekshmi C. Pillai <lekshmi.cpillai@in.ibm.com>
Tested-by: Paul Nguyen <nguyenp@us.ibm.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
|
|
While debugging a problem, I thought that using
cr4_set_bits_and_update_boot() to restore CR4.PCIDE would be
helpful. It turns out to be counterproductive.
Add a comment documenting how this works.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
When Linux brings a CPU down and back up, it switches to init_mm and then
loads swapper_pg_dir into CR3. With PCID enabled, this has the side effect
of masking off the ASID bits in CR3.
This can result in some confusion in the TLB handling code. If we
bring a CPU down and back up with any ASID other than 0, we end up
with the wrong ASID active on the CPU after resume. This could
cause our internal state to become corrupt, although major
corruption is unlikely because init_mm doesn't have any user pages.
More obviously, if CONFIG_DEBUG_VM=y, we'll trip over an assertion
in the next context switch. The result of *that* is a failure to
resume from suspend with probability 1 - 1/6^(cpus-1).
Fix it by reinitializing cpu_tlbstate on resume and CPU bringup.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Jiri Kosina <jikos@kernel.org>
Fixes: 10af6235e0d3 ("x86/mm: Implement PCID based optimization: try to preserve old TLB entries using PCID")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Introduce MADV_WIPEONFORK semantics, which result in a VMA being empty
in the child process after fork. This differs from MADV_DONTFORK in one
important way.
If a child process accesses memory that was MADV_WIPEONFORK, it will get
zeroes. The address ranges are still valid, they are just empty.
If a child process accesses memory that was MADV_DONTFORK, it will get a
segmentation fault, since those address ranges are no longer valid in
the child after fork.
Since MADV_DONTFORK also seems to be used to allow very large programs
to fork in systems with strict memory overcommit restrictions, changing
the semantics of MADV_DONTFORK might break existing programs.
MADV_WIPEONFORK only works on private, anonymous VMAs.
The use case is libraries that store or cache information, and want to
know that they need to regenerate it in the child process after fork.
Examples of this would be:
- systemd/pulseaudio API checks (fail after fork) (replacing a getpid
check, which is too slow without a PID cache)
- PKCS#11 API reinitialization check (mandated by specification)
- glibc's upcoming PRNG (reseed after fork)
- OpenSSL PRNG (reseed after fork)
The security benefits of a forking server having a re-inialized PRNG in
every child process are pretty obvious. However, due to libraries
having all kinds of internal state, and programs getting compiled with
many different versions of each library, it is unreasonable to expect
calling programs to re-initialize everything manually after fork.
A further complication is the proliferation of clone flags, programs
bypassing glibc's functions to call clone directly, and programs calling
unshare, causing the glibc pthread_atfork hook to not get called.
It would be better to have the kernel take care of this automatically.
The patch also adds MADV_KEEPONFORK, to undo the effects of a prior
MADV_WIPEONFORK.
This is similar to the OpenBSD minherit syscall with MAP_INHERIT_ZERO:
https://man.openbsd.org/minherit.2
[akpm@linux-foundation.org: numerically order arch/parisc/include/uapi/asm/mman.h #defines]
Link: http://lkml.kernel.org/r/20170811212829.29186-3-riel@redhat.com
Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Florian Weimer <fweimer@redhat.com>
Reported-by: Colm MacCártaigh <colm@allcosts.net>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "mm,fork,security: introduce MADV_WIPEONFORK", v4.
If a child process accesses memory that was MADV_WIPEONFORK, it will get
zeroes. The address ranges are still valid, they are just empty.
If a child process accesses memory that was MADV_DONTFORK, it will get a
segmentation fault, since those address ranges are no longer valid in
the child after fork.
Since MADV_DONTFORK also seems to be used to allow very large programs
to fork in systems with strict memory overcommit restrictions, changing
the semantics of MADV_DONTFORK might break existing programs.
The use case is libraries that store or cache information, and want to
know that they need to regenerate it in the child process after fork.
Examples of this would be:
- systemd/pulseaudio API checks (fail after fork) (replacing a getpid
check, which is too slow without a PID cache)
- PKCS#11 API reinitialization check (mandated by specification)
- glibc's upcoming PRNG (reseed after fork)
- OpenSSL PRNG (reseed after fork)
The security benefits of a forking server having a re-inialized PRNG in
every child process are pretty obvious. However, due to libraries
having all kinds of internal state, and programs getting compiled with
many different versions of each library, it is unreasonable to expect
calling programs to re-initialize everything manually after fork.
A further complication is the proliferation of clone flags, programs
bypassing glibc's functions to call clone directly, and programs calling
unshare, causing the glibc pthread_atfork hook to not get called.
It would be better to have the kernel take care of this automatically.
The patchset also adds MADV_KEEPONFORK, to undo the effects of a prior
MADV_WIPEONFORK.
This is similar to the OpenBSD minherit syscall with MAP_INHERIT_ZERO:
https://man.openbsd.org/minherit.2
This patch (of 2):
MPX only seems to be available on 64 bit CPUs, starting with Skylake and
Goldmont. Move VM_MPX into the 64 bit only portion of vma->vm_flags, in
order to free up a VMA flag.
Link: http://lkml.kernel.org/r/20170811212829.29186-2-riel@redhat.com
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Colm MacCártaigh <colm@allcosts.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
/proc/pid/smaps_rollup is a new proc file that improves the performance
of user programs that determine aggregate memory statistics (e.g., total
PSS) of a process.
Android regularly "samples" the memory usage of various processes in
order to balance its memory pool sizes. This sampling process involves
opening /proc/pid/smaps and summing certain fields. For very large
processes, sampling memory use this way can take several hundred
milliseconds, due mostly to the overhead of the seq_printf calls in
task_mmu.c.
smaps_rollup improves the situation. It contains most of the fields of
/proc/pid/smaps, but instead of a set of fields for each VMA,
smaps_rollup instead contains one synthetic smaps-format entry
representing the whole process. In the single smaps_rollup synthetic
entry, each field is the summation of the corresponding field in all of
the real-smaps VMAs. Using a common format for smaps_rollup and smaps
allows userspace parsers to repurpose parsers meant for use with
non-rollup smaps for smaps_rollup, and it allows userspace to switch
between smaps_rollup and smaps at runtime (say, based on the
availability of smaps_rollup in a given kernel) with minimal fuss.
By using smaps_rollup instead of smaps, a caller can avoid the
significant overhead of formatting, reading, and parsing each of a large
process's potentially very numerous memory mappings. For sampling
system_server's PSS in Android, we measured a 12x speedup, representing
a savings of several hundred milliseconds.
One alternative to a new per-process proc file would have been including
PSS information in /proc/pid/status. We considered this option but
thought that PSS would be too expensive (by a few orders of magnitude)
to collect relative to what's already emitted as part of
/proc/pid/status, and slowing every user of /proc/pid/status for the
sake of readers that happen to want PSS feels wrong.
The code itself works by reusing the existing VMA-walking framework we
use for regular smaps generation and keeping the mem_size_stats
structure around between VMA walks instead of using a fresh one for each
VMA. In this way, summation happens automatically. We let seq_file
walk over the VMAs just as it does for regular smaps and just emit
nothing to the seq_file until we hit the last VMA.
Benchmarks:
using smaps:
iterations:1000 pid:1163 pss:220023808
0m29.46s real 0m08.28s user 0m20.98s system
using smaps_rollup:
iterations:1000 pid:1163 pss:220702720
0m04.39s real 0m00.03s user 0m04.31s system
We're using the PSS samples we collect asynchronously for
system-management tasks like fine-tuning oom_adj_score, memory use
tracking for debugging, application-level memory-use attribution, and
deciding whether we want to kill large processes during system idle
maintenance windows. Android has been using PSS for these purposes for
a long time; as the average process VMA count has increased and and
devices become more efficiency-conscious, PSS-collection inefficiency
has started to matter more. IMHO, it'd be a lot safer to optimize the
existing PSS-collection model, which has been fine-tuned over the years,
instead of changing the memory tracking approach entirely to work around
smaps-generation inefficiency.
Tim said:
: There are two main reasons why Android gathers PSS information:
:
: 1. Android devices can show the user the amount of memory used per
: application via the settings app. This is a less important use case.
:
: 2. We log PSS to help identify leaks in applications. We have found
: an enormous number of bugs (in the Android platform, in Google's own
: apps, and in third-party applications) using this data.
:
: To do this, system_server (the main process in Android userspace) will
: sample the PSS of a process three seconds after it changes state (for
: example, app is launched and becomes the foreground application) and about
: every ten minutes after that. The net result is that PSS collection is
: regularly running on at least one process in the system (usually a few
: times a minute while the screen is on, less when screen is off due to
: suspend). PSS of a process is an incredibly useful stat to track, and we
: aren't going to get rid of it. We've looked at some very hacky approaches
: using RSS ("take the RSS of the target process, subtract the RSS of the
: zygote process that is the parent of all Android apps") to reduce the
: accounting time, but it regularly overestimated the memory used by 20+
: percent. Accordingly, I don't think that there's a good alternative to
: using PSS.
:
: We started looking into PSS collection performance after we noticed random
: frequency spikes while a phone's screen was off; occasionally, one of the
: CPU clusters would ramp to a high frequency because there was 200-300ms of
: constant CPU work from a single thread in the main Android userspace
: process. The work causing the spike (which is reasonable governor
: behavior given the amount of CPU time needed) was always PSS collection.
: As a result, Android is burning more power than we should be on PSS
: collection.
:
: The other issue (and why I'm less sure about improving smaps as a
: long-term solution) is that the number of VMAs per process has increased
: significantly from release to release. After trying to figure out why we
: were seeing these 200-300ms PSS collection times on Android O but had not
: noticed it in previous versions, we found that the number of VMAs in the
: main system process increased by 50% from Android N to Android O (from
: ~1800 to ~2700) and varying increases in every userspace process. Android
: M to N also had an increase in the number of VMAs, although not as much.
: I'm not sure why this is increasing so much over time, but thinking about
: ASLR and ways to make ASLR better, I expect that this will continue to
: increase going forward. I would not be surprised if we hit 5000 VMAs on
: the main Android process (system_server) by 2020.
:
: If we assume that the number of VMAs is going to increase over time, then
: doing anything we can do to reduce the overhead of each VMA during PSS
: collection seems like the right way to go, and that means outputting an
: aggregate statistic (to avoid whatever overhead there is per line in
: writing smaps and in reading each line from userspace).
Link: http://lkml.kernel.org/r/20170812022148.178293-1-dancol@google.com
Signed-off-by: Daniel Colascione <dancol@google.com>
Cc: Tim Murray <timmurray@google.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sonny Rao <sonnyrao@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Huge page helps to reduce TLB miss rate, but it has higher cache
footprint, sometimes this may cause some issue. For example, when
clearing huge page on x86_64 platform, the cache footprint is 2M. But
on a Xeon E5 v3 2699 CPU, there are 18 cores, 36 threads, and only 45M
LLC (last level cache). That is, in average, there are 2.5M LLC for
each core and 1.25M LLC for each thread.
If the cache pressure is heavy when clearing the huge page, and we clear
the huge page from the begin to the end, it is possible that the begin
of huge page is evicted from the cache after we finishing clearing the
end of the huge page. And it is possible for the application to access
the begin of the huge page after clearing the huge page.
To help the above situation, in this patch, when we clear a huge page,
the order to clear sub-pages is changed. In quite some situation, we
can get the address that the application will access after we clear the
huge page, for example, in a page fault handler. Instead of clearing
the huge page from begin to end, we will clear the sub-pages farthest
from the the sub-page to access firstly, and clear the sub-page to
access last. This will make the sub-page to access most cache-hot and
sub-pages around it more cache-hot too. If we cannot know the address
the application will access, the begin of the huge page is assumed to be
the the address the application will access.
With this patch, the throughput increases ~28.3% in vm-scalability
anon-w-seq test case with 72 processes on a 2 socket Xeon E5 v3 2699
system (36 cores, 72 threads). The test case creates 72 processes, each
process mmap a big anonymous memory area and writes to it from the begin
to the end. For each process, other processes could be seen as other
workload which generates heavy cache pressure. At the same time, the
cache miss rate reduced from ~33.4% to ~31.7%, the IPC (instruction per
cycle) increased from 0.56 to 0.74, and the time spent in user space is
reduced ~7.9%
Christopher Lameter suggests to clear bytes inside a sub-page from end
to begin too. But tests show no visible performance difference in the
tests. May because the size of page is small compared with the cache
size.
Thanks Andi Kleen to propose to use address to access to determine the
order of sub-pages to clear.
The hugetlbfs access address could be improved, will do that in another
patch.
[ying.huang@intel.com: improve readability of clear_huge_page()]
Link: http://lkml.kernel.org/r/20170830051842.1397-1-ying.huang@intel.com
Link: http://lkml.kernel.org/r/20170815014618.15842-1-ying.huang@intel.com
Suggested-by: Andi Kleen <andi.kleen@intel.com>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Jan Kara <jack@suse.cz>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Nadia Yvette Chambers <nyc@holomorphy.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
This is purely required because exit_aio() may block and exit_mmap() may
never start, if the oom_reap_task cannot start running on a mm with
mm_users == 0.
At the same time if the OOM reaper doesn't wait at all for the memory of
the current OOM candidate to be freed by exit_mmap->unmap_vmas, it would
generate a spurious OOM kill.
If it wasn't because of the exit_aio or similar blocking functions in
the last mmput, it would be enough to change the oom_reap_task() in the
case it finds mm_users == 0, to wait for a timeout or to wait for
__mmput to set MMF_OOM_SKIP itself, but it's not just exit_mmap the
problem here so the concurrency of exit_mmap and oom_reap_task is
apparently warranted.
It's a non standard runtime, exit_mmap() runs without mmap_sem, and
oom_reap_task runs with the mmap_sem for reading as usual (kind of
MADV_DONTNEED).
The race between the two is solved with a combination of
tsk_is_oom_victim() (serialized by task_lock) and MMF_OOM_SKIP
(serialized by a dummy down_write/up_write cycle on the same lines of
the ksm_exit method).
If the oom_reap_task() may be running concurrently during exit_mmap,
exit_mmap will wait it to finish in down_write (before taking down mm
structures that would make the oom_reap_task fail with use after free).
If exit_mmap comes first, oom_reap_task() will skip the mm if
MMF_OOM_SKIP is already set and in turn all memory is already freed and
furthermore the mm data structures may already have been taken down by
free_pgtables.
[aarcange@redhat.com: incremental one liner]
Link: http://lkml.kernel.org/r/20170726164319.GC29716@redhat.com
[rientjes@google.com: remove unused mmput_async]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708141733130.50317@chino.kir.corp.google.com
[aarcange@redhat.com: microoptimization]
Link: http://lkml.kernel.org/r/20170817171240.GB5066@redhat.com
Link: http://lkml.kernel.org/r/20170726162912.GA29716@redhat.com
Fixes: 26db62f179d1 ("oom: keep mm of the killed task available")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: David Rientjes <rientjes@google.com>
Tested-by: David Rientjes <rientjes@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
If the system has more than one swap device and swap device has the node
information, we can make use of this information to decide which swap
device to use in get_swap_pages() to get better performance.
The current code uses a priority based list, swap_avail_list, to decide
which swap device to use and if multiple swap devices share the same
priority, they are used round robin. This patch changes the previous
single global swap_avail_list into a per-numa-node list, i.e. for each
numa node, it sees its own priority based list of available swap
devices. Swap device's priority can be promoted on its matching node's
swap_avail_list.
The current swap device's priority is set as: user can set a >=0 value,
or the system will pick one starting from -1 then downwards. The
priority value in the swap_avail_list is the negated value of the swap
device's due to plist being sorted from low to high. The new policy
doesn't change the semantics for priority >=0 cases, the previous
starting from -1 then downwards now becomes starting from -2 then
downwards and -1 is reserved as the promoted value.
Take 4-node EX machine as an example, suppose 4 swap devices are
available, each sit on a different node:
swapA on node 0
swapB on node 1
swapC on node 2
swapD on node 3
After they are all swapped on in the sequence of ABCD.
Current behaviour:
their priorities will be:
swapA: -1
swapB: -2
swapC: -3
swapD: -4
And their position in the global swap_avail_list will be:
swapA -> swapB -> swapC -> swapD
prio:1 prio:2 prio:3 prio:4
New behaviour:
their priorities will be(note that -1 is skipped):
swapA: -2
swapB: -3
swapC: -4
swapD: -5
And their positions in the 4 swap_avail_lists[nid] will be:
swap_avail_lists[0]: /* node 0's available swap device list */
swapA -> swapB -> swapC -> swapD
prio:1 prio:3 prio:4 prio:5
swap_avali_lists[1]: /* node 1's available swap device list */
swapB -> swapA -> swapC -> swapD
prio:1 prio:2 prio:4 prio:5
swap_avail_lists[2]: /* node 2's available swap device list */
swapC -> swapA -> swapB -> swapD
prio:1 prio:2 prio:3 prio:5
swap_avail_lists[3]: /* node 3's available swap device list */
swapD -> swapA -> swapB -> swapC
prio:1 prio:2 prio:3 prio:4
To see the effect of the patch, a test that starts N process, each mmap
a region of anonymous memory and then continually write to it at random
position to trigger both swap in and out is used.
On a 2 node Skylake EP machine with 64GiB memory, two 170GB SSD drives
are used as swap devices with each attached to a different node, the
result is:
runtime=30m/processes=32/total test size=128G/each process mmap region=4G
kernel throughput
vanilla 13306
auto-binding 15169 +14%
runtime=30m/processes=64/total test size=128G/each process mmap region=2G
kernel throughput
vanilla 11885
auto-binding 14879 +25%
[aaron.lu@intel.com: v2]
Link: http://lkml.kernel.org/r/20170814053130.GD2369@aaronlu.sh.intel.com
Link: http://lkml.kernel.org/r/20170816024439.GA10925@aaronlu.sh.intel.com
[akpm@linux-foundation.org: use kmalloc_array()]
Link: http://lkml.kernel.org/r/20170814053130.GD2369@aaronlu.sh.intel.com
Link: http://lkml.kernel.org/r/20170816024439.GA10925@aaronlu.sh.intel.com
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
TIF_MEMDIE is set only to the tasks whick were either directly selected
by the OOM killer or passed through mark_oom_victim from the allocator
path. tsk_is_oom_victim is more generic and allows to identify all
tasks (threads) which share the mm with the oom victim.
Please note that the freezer still needs to check TIF_MEMDIE because we
cannot thaw tasks which do not participage in oom_victims counting
otherwise a !TIF_MEMDIE task could interfere after oom_disbale returns.
Link: http://lkml.kernel.org/r/20170810075019.28998-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
For ages we have been relying on TIF_MEMDIE thread flag to mark OOM
victims and then, among other things, to give these threads full access
to memory reserves. There are few shortcomings of this implementation,
though.
First of all and the most serious one is that the full access to memory
reserves is quite dangerous because we leave no safety room for the
system to operate and potentially do last emergency steps to move on.
Secondly this flag is per task_struct while the OOM killer operates on
mm_struct granularity so all processes sharing the given mm are killed.
Giving the full access to all these task_structs could lead to a quick
memory reserves depletion. We have tried to reduce this risk by giving
TIF_MEMDIE only to the main thread and the currently allocating task but
that doesn't really solve this problem while it surely opens up a room
for corner cases - e.g. GFP_NO{FS,IO} requests might loop inside the
allocator without access to memory reserves because a particular thread
was not the group leader.
Now that we have the oom reaper and that all oom victims are reapable
after 1b51e65eab64 ("oom, oom_reaper: allow to reap mm shared by the
kthreads") we can be more conservative and grant only partial access to
memory reserves because there are reasonable chances of the parallel
memory freeing. We still want some access to reserves because we do not
want other consumers to eat up the victim's freed memory. oom victims
will still contend with __GFP_HIGH users but those shouldn't be so
aggressive to starve oom victims completely.
Introduce ALLOC_OOM flag and give all tsk_is_oom_victim tasks access to
the half of the reserves. This makes the access to reserves independent
on which task has passed through mark_oom_victim. Also drop any usage
of TIF_MEMDIE from the page allocator proper and replace it by
tsk_is_oom_victim as well which will make page_alloc.c completely
TIF_MEMDIE free finally.
CONFIG_MMU=n doesn't have oom reaper so let's stick to the original
ALLOC_NO_WATERMARKS approach.
There is a demand to make the oom killer memcg aware which will imply
many tasks killed at once. This change will allow such a usecase
without worrying about complete memory reserves depletion.
Link: http://lkml.kernel.org/r/20170810075019.28998-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
It's been noted that z3fold doesn't scale well when it's run in a large
number of threads on many cores, which can be easily reproduced with fio
'randrw' test with --numjobs=32. E.g. the result for 1 cluster (4 cores)
is:
Run status group 0 (all jobs):
READ: io=244785MB, aggrb=496883KB/s, minb=15527KB/s, ...
WRITE: io=246735MB, aggrb=500841KB/s, minb=15651KB/s, ...
While for 8 cores (2 clusters) the result is:
Run status group 0 (all jobs):
READ: io=244785MB, aggrb=265942KB/s, minb=8310KB/s, ...
WRITE: io=246735MB, aggrb=268060KB/s, minb=8376KB/s, ...
The bottleneck here is the pool lock which many threads become waiting
upon. To reduce that spin lock contention, z3fold can operate only on
the lists local to the current CPU whenever possible. Due to the nature
of z3fold unbuddied list handling (it only takes the first entry off the
list on a hot path), if the z3fold pool is big enough and balanced well
enough, limiting search to only local unbuddied list doesn't lead to a
significant compression ratio degrade (2.57x vs 2.65x in our
measurements).
This patch also introduces two worker threads: one for async in-page
object layout optimization and one for releasing freed pages. This is
done to speed up z3fold_free() which is often on a hot path.
The fio results for 8-core case are now the following:
Run status group 0 (all jobs):
READ: io=244785MB, aggrb=1568.3MB/s, minb=50182KB/s, ...
WRITE: io=246735MB, aggrb=1580.8MB/s, minb=50582KB/s, ...
So we're in for almost 6x performance increase.
Link: http://lkml.kernel.org/r/20170806181443.f9b65018f8bde25ef990f9e8@gmail.com
Signed-off-by: Vitaly Wool <vitalywool@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
VMA based swap readahead will readahead the virtual pages that is
continuous in the virtual address space. While the original swap
readahead will readahead the swap slots that is continuous in the swap
device. Although VMA based swap readahead is more correct for the swap
slots to be readahead, it will trigger more small random readings, which
may cause the performance of HDD (hard disk) to degrade heavily, and may
finally exceed the benefit.
To avoid the issue, in this patch, if the HDD is used as swap, the VMA
based swap readahead will be disabled, and the original swap readahead
will be used instead.
Link: http://lkml.kernel.org/r/20170807054038.1843-6-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The sysfs interface to control the VMA based swap readahead is added as
follow,
/sys/kernel/mm/swap/vma_ra_enabled
Enable the VMA based swap readahead algorithm, or use the original
global swap readahead algorithm.
/sys/kernel/mm/swap/vma_ra_max_order
Set the max order of the readahead window size for the VMA based swap
readahead algorithm.
The corresponding ABI documentation is added too.
Link: http://lkml.kernel.org/r/20170807054038.1843-5-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
The swap readahead is an important mechanism to reduce the swap in
latency. Although pure sequential memory access pattern isn't very
popular for anonymous memory, the space locality is still considered
valid.
In the original swap readahead implementation, the consecutive blocks in
swap device are readahead based on the global space locality estimation.
But the consecutive blocks in swap device just reflect the order of page
reclaiming, don't necessarily reflect the access pattern in virtual
memory. And the different tasks in the system may have different access
patterns, which makes the global space locality estimation incorrect.
In this patch, when page fault occurs, the virtual pages near the fault
address will be readahead instead of the swap slots near the fault swap
slot in swap device. This avoid to readahead the unrelated swap slots.
At the same time, the swap readahead is changed to work on per-VMA from
globally. So that the different access patterns of the different VMAs
could be distinguished, and the different readahead policy could be
applied accordingly. The original core readahead detection and scaling
algorithm is reused, because it is an effect algorithm to detect the
space locality.
The test and result is as follow,
Common test condition
=====================
Test Machine: Xeon E5 v3 (2 sockets, 72 threads, 32G RAM) Swap device:
NVMe disk
Micro-benchmark with combined access pattern
============================================
vm-scalability, sequential swap test case, 4 processes to eat 50G
virtual memory space, repeat the sequential memory writing until 300
seconds. The first round writing will trigger swap out, the following
rounds will trigger sequential swap in and out.
At the same time, run vm-scalability random swap test case in
background, 8 processes to eat 30G virtual memory space, repeat the
random memory write until 300 seconds. This will trigger random swap-in
in the background.
This is a combined workload with sequential and random memory accessing
at the same time. The result (for sequential workload) is as follow,
Base Optimized
---- ---------
throughput 345413 KB/s 414029 KB/s (+19.9%)
latency.average 97.14 us 61.06 us (-37.1%)
latency.50th 2 us 1 us
latency.60th 2 us 1 us
latency.70th 98 us 2 us
latency.80th 160 us 2 us
latency.90th 260 us 217 us
latency.95th 346 us 369 us
latency.99th 1.34 ms 1.09 ms
ra_hit% 52.69% 99.98%
The original swap readahead algorithm is confused by the background
random access workload, so readahead hit rate is lower. The VMA-base
readahead algorithm works much better.
Linpack
=======
The test memory size is bigger than RAM to trigger swapping.
Base Optimized
---- ---------
elapsed_time 393.49 s 329.88 s (-16.2%)
ra_hit% 86.21% 98.82%
The score of base and optimized kernel hasn't visible changes. But the
elapsed time reduced and readahead hit rate improved, so the optimized
kernel runs better for startup and tear down stages. And the absolute
value of readahead hit rate is high, shows that the space locality is
still valid in some practical workloads.
Link: http://lkml.kernel.org/r/20170807054038.1843-4-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In the original implementation, it is possible that the existing pages
in the swap cache (not newly readahead) could be marked as the readahead
pages. This will cause the statistics of swap readahead be wrong and
influence the swap readahead algorithm too.
This is fixed via marking a page as the readahead page only if it is
newly allocated and read from the disk.
When testing with linpack, after the fixing the swap readahead hit rate
increased from ~66% to ~86%.
Link: http://lkml.kernel.org/r/20170807054038.1843-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "mm, swap: VMA based swap readahead", v4.
The swap readahead is an important mechanism to reduce the swap in
latency. Although pure sequential memory access pattern isn't very
popular for anonymous memory, the space locality is still considered
valid.
In the original swap readahead implementation, the consecutive blocks in
swap device are readahead based on the global space locality estimation.
But the consecutive blocks in swap device just reflect the order of page
reclaiming, don't necessarily reflect the access pattern in virtual
memory space. And the different tasks in the system may have different
access patterns, which makes the global space locality estimation
incorrect.
In this patchset, when page fault occurs, the virtual pages near the
fault address will be readahead instead of the swap slots near the fault
swap slot in swap device. This avoid to readahead the unrelated swap
slots. At the same time, the swap readahead is changed to work on
per-VMA from globally. So that the different access patterns of the
different VMAs could be distinguished, and the different readahead
policy could be applied accordingly. The original core readahead
detection and scaling algorithm is reused, because it is an effect
algorithm to detect the space locality.
In addition to the swap readahead changes, some new sysfs interface is
added to show the efficiency of the readahead algorithm and some other
swap statistics.
This new implementation will incur more small random read, on SSD, the
improved correctness of estimation and readahead target should beat the
potential increased overhead, this is also illustrated in the test
results below. But on HDD, the overhead may beat the benefit, so the
original implementation will be used by default.
The test and result is as follow,
Common test condition
=====================
Test Machine: Xeon E5 v3 (2 sockets, 72 threads, 32G RAM)
Swap device: NVMe disk
Micro-benchmark with combined access pattern
============================================
vm-scalability, sequential swap test case, 4 processes to eat 50G
virtual memory space, repeat the sequential memory writing until 300
seconds. The first round writing will trigger swap out, the following
rounds will trigger sequential swap in and out.
At the same time, run vm-scalability random swap test case in
background, 8 processes to eat 30G virtual memory space, repeat the
random memory write until 300 seconds. This will trigger random swap-in
in the background.
This is a combined workload with sequential and random memory accessing
at the same time. The result (for sequential workload) is as follow,
Base Optimized
---- ---------
throughput 345413 KB/s 414029 KB/s (+19.9%)
latency.average 97.14 us 61.06 us (-37.1%)
latency.50th 2 us 1 us
latency.60th 2 us 1 us
latency.70th 98 us 2 us
latency.80th 160 us 2 us
latency.90th 260 us 217 us
latency.95th 346 us 369 us
latency.99th 1.34 ms 1.09 ms
ra_hit% 52.69% 99.98%
The original swap readahead algorithm is confused by the background
random access workload, so readahead hit rate is lower. The VMA-base
readahead algorithm works much better.
Linpack
=======
The test memory size is bigger than RAM to trigger swapping.
Base Optimized
---- ---------
elapsed_time 393.49 s 329.88 s (-16.2%)
ra_hit% 86.21% 98.82%
The score of base and optimized kernel hasn't visible changes. But the
elapsed time reduced and readahead hit rate improved, so the optimized
kernel runs better for startup and tear down stages. And the absolute
value of readahead hit rate is high, shows that the space locality is
still valid in some practical workloads.
This patch (of 5):
The statistics for total readahead pages and total readahead hits are
recorded and exported via the following sysfs interface.
/sys/kernel/mm/swap/ra_hits
/sys/kernel/mm/swap/ra_total
With them, the efficiency of the swap readahead could be measured, so
that the swap readahead algorithm and parameters could be tuned
accordingly.
[akpm@linux-foundation.org: don't display swap stats if CONFIG_SWAP=n]
Link: http://lkml.kernel.org/r/20170807054038.1843-2-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Jérôme Glisse
Michal Hocko
Naoya Horiguchi
Zi Yan
Linus Torvalds
Leon Romanovsky
Mauricio Faria de Oliveira
Andy Lutomirski
Rik van Riel
Daniel Colascione
Huang Ying
Andrea Arcangeli
Aaron Lu
Vitaly Wool