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mm, page_alloc: remove unnecessary taking of a seqlock when cpusets are disabled

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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@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2015-11-06 16:28:15 -08:00 committed by Linus Torvalds
parent c9ab0c4fbe
commit 46e700abc4
1 changed files with 6 additions and 0 deletions
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6
include/linux/cpuset.h
View file

@ -104,6 +104,9 @@ extern void cpuset_print_current_mems_allowed(void);
*/
static inline unsigned int read_mems_allowed_begin(void)
{
if (!cpusets_enabled())
return 0;
return read_seqcount_begin(&current->mems_allowed_seq);
}
@ -115,6 +118,9 @@ static inline unsigned int read_mems_allowed_begin(void)
*/
static inline bool read_mems_allowed_retry(unsigned int seq)
{
if (!cpusets_enabled())
return false;
return read_seqcount_retry(&current->mems_allowed_seq, seq);
}