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| author |   Robin Holt <holt@sgi.com> | 2010-04-23 10:36:22 -0500 |
|---|---|---|
| committer |   H. Peter Anvin <hpa@zytor.com> | 2010-04-23 15:57:23 -0700 |
| commit | 1f9cc3cb6a27521edfe0a21abf97d2bb11c4d237 (patch) | |
| tree | c9af6a71398aed690c1fa813498a0aed8abf2d7b /include/linux/rbtree.h | |
| parent | x86, pat: In rbt_memtype_check_insert(), update new->type only if valid (diff) | |
| download | linux-dev-1f9cc3cb6a27521edfe0a21abf97d2bb11c4d237.tar.xz linux-dev-1f9cc3cb6a27521edfe0a21abf97d2bb11c4d237.zip | |
x86, pat: Update the page flags for memtype atomically instead of using memtype_lock
While testing an application using the xpmem (out of kernel) driver, we
noticed a significant page fault rate reduction of x86_64 with respect
to ia64. For one test running with 32 cpus, one thread per cpu, it
took 01:08 for each of the threads to vm_insert_pfn 2GB worth of pages.
For the same test running on 256 cpus, one thread per cpu, it took 14:48
to vm_insert_pfn 2 GB worth of pages.
The slowdown was tracked to lookup_memtype which acquires the
spinlock memtype_lock. This heavily contended lock was slowing down
vm_insert_pfn().
With the cmpxchg on page->flags method, both the 32 cpu and 256 cpu
cases take approx 00:01.3 seconds to complete.
Signed-off-by: Robin Holt <holt@sgi.com>
LKML-Reference: <20100423153627.751194346@gulag1.americas.sgi.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@gmail.com>
Cc: Rafael Wysocki <rjw@novell.com>
Reviewed-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'include/linux/rbtree.h')
0 files changed, 0 insertions, 0 deletions