The patch titled
Subject: mm, page_alloc: remove unnecessary taking of a seqlock when cpusets are disabled
has been added to the -mm tree. Its filename is
mm-page_alloc-remove-unnecessary-taking-of-a-seqlock-when-cpusets-are-disabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-remove-unnecessary-taking-of-a-seqlock-when-cpusets-are-disabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-remove-unnecessary-taking-of-a-seqlock-when-cpusets-are-disabled.patch
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm, page_alloc: remove unnecessary taking of a seqlock when cpusets are disabled
There is a seqcounter that protects against spurious allocation failures
when a task is changing the allowed nodes in a cpuset. There is no need
to check the seqcounter until a cpuset exists.
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cpuset.h | 6 ++++++
1 file changed, 6 insertions(+)
diff -puN include/linux/cpuset.h~mm-page_alloc-remove-unnecessary-taking-of-a-seqlock-when-cpusets-are-disabled include/linux/cpuset.h
--- a/include/linux/cpuset.h~mm-page_alloc-remove-unnecessary-taking-of-a-seqlock-when-cpusets-are-disabled
+++ a/include/linux/cpuset.h
@@ -104,6 +104,9 @@ extern void cpuset_print_current_mems_al
*/
static inline unsigned int read_mems_allowed_begin(void)
{
+ if (!cpusets_enabled())
+ return 0;
+
return read_seqcount_begin(¤t->mems_allowed_seq);
}
@@ -115,6 +118,9 @@ static inline unsigned int read_mems_all
*/
static inline bool read_mems_allowed_retry(unsigned int seq)
{
+ if (!cpusets_enabled())
+ return false;
+
return read_seqcount_retry(¤t->mems_allowed_seq, seq);
}
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
mm-hugetlbfs-skip-shared-vmas-when-unmapping-private-pages-to-satisfy-a-fault.patch
mm-page_alloc-remove-unnecessary-parameter-from-zone_watermark_ok_safe.patch
mm-page_alloc-remove-unnecessary-recalculations-for-dirty-zone-balancing.patch
mm-page_alloc-remove-unnecessary-taking-of-a-seqlock-when-cpusets-are-disabled.patch
mm-page_alloc-use-masks-and-shifts-when-converting-gfp-flags-to-migrate-types.patch
mm-page_alloc-distinguish-between-being-unable-to-sleep-unwilling-to-sleep-and-avoiding-waking-kswapd.patch
mm-page_alloc-rename-__gfp_wait-to-__gfp_reclaim.patch
mm-page_alloc-delete-the-zonelist_cache.patch
mm-page_alloc-remove-migrate_reserve.patch
mm-page_alloc-reserve-pageblocks-for-high-order-atomic-allocations-on-demand.patch
mm-page_alloc-only-enforce-watermarks-for-order-0-allocations.patch
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