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Pull x86 cache allocation interface from Thomas Gleixner:
"This provides support for Intel's Cache Allocation Technology, a cache
partitioning mechanism.
The interface is odd, but the hardware interface of that CAT stuff is
odd as well.
We tried hard to come up with an abstraction, but that only allows
rather simple partitioning, but no way of sharing and dealing with the
per package nature of this mechanism.
In the end we decided to expose the allocation bitmaps directly so all
combinations of the hardware can be utilized.
There are two ways of associating a cache partition:
- Task
A task can be added to a resource group. It uses the cache
partition associated to the group.
- CPU
All tasks which are not member of a resource group use the group to
which the CPU they are running on is associated with.
That allows for simple CPU based partitioning schemes.
The main expected user sare:
- Virtualization so a VM can only trash only the associated part of
the cash w/o disturbing others
- Real-Time systems to seperate RT and general workloads.
- Latency sensitive enterprise workloads
- In theory this also can be used to protect against cache side
channel attacks"
[ Intel RDT is "Resource Director Technology". The interface really is
rather odd and very specific, which delayed this pull request while I
was thinking about it. The pull request itself came in early during
the merge window, I just delayed it until things had calmed down and I
had more time.
But people tell me they'll use this, and the good news is that it is
_so_ specific that it's rather independent of anything else, and no
user is going to depend on the interface since it's pretty rare. So if
push comes to shove, we can just remove the interface and nothing will
break ]
* 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
x86/intel_rdt: Implement show_options() for resctrlfs
x86/intel_rdt: Call intel_rdt_sched_in() with preemption disabled
x86/intel_rdt: Update task closid immediately on CPU in rmdir and unmount
x86/intel_rdt: Fix setting of closid when adding CPUs to a group
x86/intel_rdt: Update percpu closid immeditately on CPUs affected by changee
x86/intel_rdt: Reset per cpu closids on unmount
x86/intel_rdt: Select KERNFS when enabling INTEL_RDT_A
x86/intel_rdt: Prevent deadlock against hotplug lock
x86/intel_rdt: Protect info directory from removal
x86/intel_rdt: Add info files to Documentation
x86/intel_rdt: Export the minimum number of set mask bits in sysfs
x86/intel_rdt: Propagate error in rdt_mount() properly
x86/intel_rdt: Add a missing #include
MAINTAINERS: Add maintainer for Intel RDT resource allocation
x86/intel_rdt: Add scheduler hook
x86/intel_rdt: Add schemata file
x86/intel_rdt: Add tasks files
x86/intel_rdt: Add cpus file
x86/intel_rdt: Add mkdir to resctrl file system
x86/intel_rdt: Add "info" files to resctrl file system
...
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With CONFIG_OF enabled on x86, we get the following error on boot:
"
Failed to find cpu0 device node
Unable to detect cache hierarchy from DT for CPU 0
"
and the cacheinfo fails to get populated in the corresponding sysfs
entries. This is because cache_setup_of_node looks for of_node for
setting up the shared cpu_map without checking that it's already
populated in the architecture specific callback.
In order to indicate that the shared cpu_map is already populated, this
patch introduces a boolean `cpu_map_populated` in struct cpu_cacheinfo
that can be used by the generic code to skip cache_shared_cpu_map_setup.
This patch also sets that boolean for x86.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Cache management software needs an id for each instance of a cache of
a particular type.
The current cacheinfo structure does not provide any information about
the underlying hardware so there is no way to expose it.
Hardware with cache management features provides means (cpuid, enumeration
etc.) to retrieve the hardware id of a particular cache instance. Cache
instances which share hardware have the same hardware id.
Add an 'id' field to struct cacheinfo to store this information. Expose
this information under the /sys/devices/system/cpu/cpu*/cache/index*/
directory as well.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "David Carrillo-Cisneros" <davidcc@google.com>
Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Stephane Eranian" <eranian@google.com>
Cc: "Dave Hansen" <dave.hansen@intel.com>
Cc: "Shaohua Li" <shli@fb.com>
Cc: "Nilay Vaish" <nilayvaish@gmail.com>
Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com>
Cc: "Ingo Molnar" <mingo@elte.hu>
Cc: "Borislav Petkov" <bp@suse.de>
Cc: "H. Peter Anvin" <h.peter.anvin@intel.com>
Link: http://lkml.kernel.org/r/1477142405-32078-3-git-send-email-fenghua.yu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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s/hierarcy/hierarchy/
Maybe the typo will annoy people enough so that they add the missing
nodes to their device-tree files, but I still think this is better off
fixed.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This patch adds initial support for providing processor cache information
to userspace through sysfs interface. This is based on already existing
implementations(x86, ia64, s390 and powerpc) and hence the interface is
intended to be fully compatible.
The main purpose of this generic support is to avoid further code
duplication to support new architectures and also to unify all the existing
different implementations.
This implementation maintains the hierarchy of cache objects which reflects
the system's cache topology. Cache devices are instantiated as needed as
CPUs come online. The cache information is replicated per-cpu even if they are
shared. A per-cpu array of cache information maintained is used mainly for
sysfs-related book keeping.
It also implements the shared_cpu_map attribute, which is essential for
enabling both kernel and user-space to discover the system's overall cache
topology.
This patch also add the missing ABI documentation for the cacheinfo sysfs
interface already, which is well defined and widely used.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-api@vger.kernel.org
Cc: linux390@de.ibm.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: x86@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Linus Torvalds
Sudeep Holla
Fenghua Yu
Will Deacon