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mm, page_alloc: shorten the page allocator fast path

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The page allocator fast path checks page multiple times unnecessarily.
This patch avoids all the slowpath checks if the first allocation
attempt succeeds.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@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 2016-05-19 17:14:01 -07:00 committed by Linus Torvalds
parent 3777999dd4
commit 4fcb097117
1 changed files with 17 additions and 16 deletions
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33
mm/page_alloc.c
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@ -3398,31 +3398,26 @@ retry_cpuset:
ac.nodemask, &ac.preferred_zone); ac.nodemask, &ac.preferred_zone);
if (!ac.preferred_zone) { if (!ac.preferred_zone) {
page = NULL; page = NULL;
goto out; goto no_zone;
} }
ac.classzone_idx = zonelist_zone_idx(preferred_zoneref); ac.classzone_idx = zonelist_zone_idx(preferred_zoneref);
/* First allocation attempt */ /* First allocation attempt */
page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac); page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
if (unlikely(!page)) { if (likely(page))
/* goto out;
* Runtime PM, block IO and its error handling path
* can deadlock because I/O on the device might not
* complete.
*/
alloc_mask = memalloc_noio_flags(gfp_mask);
ac.spread_dirty_pages = false;
page = __alloc_pages_slowpath(alloc_mask, order, &ac); /*
} * Runtime PM, block IO and its error handling path can deadlock
* because I/O on the device might not complete.
*/
alloc_mask = memalloc_noio_flags(gfp_mask);
ac.spread_dirty_pages = false;
if (kmemcheck_enabled && page) page = __alloc_pages_slowpath(alloc_mask, order, &ac);
kmemcheck_pagealloc_alloc(page, order, gfp_mask);
trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype); no_zone:
out:
/* /*
* When updating a task's mems_allowed, it is possible to race with * When updating a task's mems_allowed, it is possible to race with
* parallel threads in such a way that an allocation can fail while * parallel threads in such a way that an allocation can fail while
@ -3434,6 +3429,12 @@ out:
goto retry_cpuset; goto retry_cpuset;
} }
out:
if (kmemcheck_enabled && page)
kmemcheck_pagealloc_alloc(page, order, gfp_mask);
trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
return page; return page;
} }
EXPORT_SYMBOL(__alloc_pages_nodemask); EXPORT_SYMBOL(__alloc_pages_nodemask);