The patch titled
Subject: mm, page_alloc: don't check cpuset allowed twice in fast-path
has been added to the -mm tree. Its filename is
mm-page_alloc-dont-check-cpuset-allowed-twice-in-fast-path.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_alloc-dont-check-cpuset-allowed-twice-in-fast-path.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_alloc-dont-check-cpuset-allowed-twice-in-fast-path.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, page_alloc: don't check cpuset allowed twice in fast-path
Since 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist
iterator") we replace a NULL nodemask with cpuset_current_mems_allowed in
the fast path, so that get_page_from_freelist() filters nodes allowed by
the cpuset via for_next_zone_zonelist_nodemask(). In that case it's
pointless to additionaly check __cpuset_zone_allowed() in each iteration,
which we can avoid by not adding ALLOC_CPUSET to alloc_flags in that
scenario.
This saves some cycles in the allocator fast path on systems with one or
more non-root cpuset configured. In the slow path, ALLOC_CPUSET is reset
according to __alloc_pages_slowpath(). Without configured cpusets, this
code is disabled by a static key.
Link: http://lkml.kernel.org/r/20170124150511.5710-2-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-page_alloc-dont-check-cpuset-allowed-twice-in-fast-path mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-dont-check-cpuset-allowed-twice-in-fast-path
+++ a/mm/page_alloc.c
@@ -3900,9 +3900,10 @@ static inline bool prepare_alloc_pages(g
if (cpusets_enabled()) {
*alloc_mask |= __GFP_HARDWALL;
- *alloc_flags |= ALLOC_CPUSET;
if (!ac->nodemask)
ac->nodemask = &cpuset_current_mems_allowed;
+ else
+ *alloc_flags |= ALLOC_CPUSET;
}
lockdep_trace_alloc(gfp_mask);
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-mempolicyc-do-not-put-mempolicy-before-using-its-nodemask.patch
mm-page_alloc-fix-check-for-null-preferred_zone.patch
mm-page_alloc-fix-fast-path-race-with-cpuset-update-or-removal.patch
mm-page_alloc-move-cpuset-seqcount-checking-to-slowpath.patch
mm-page_alloc-fix-premature-oom-when-racing-with-cpuset-mems-update.patch
mm-page_alloc-dont-convert-pfn-to-idx-when-merging.patch
mm-page_alloc-avoid-page_to_pfn-when-merging-buddies.patch
mm-page_alloc-remove-redundant-checks-from-alloc-fastpath.patch
mm-page_alloc-dont-check-cpuset-allowed-twice-in-fast-path.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
