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authorAndrea Arcangeli <aarcange@redhat.com>2011-01-13 18:46:49 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 20:32:41 -0500
commit32dba98e085f8b2b4345887df9abf5e0e93bfc12 (patch)
tree6789196797350911a1c370ce909bfde2556ccfc4 /mm/page_alloc.c
parent936a5fe6e6148c0b3ea0d792b903847d9b9931a1 (diff)
thp: _GFP_NO_KSWAPD
Transparent hugepage allocations must be allowed not to invoke kswapd or any other kind of indirect reclaim (especially when the defrag sysfs is control disabled). It's unacceptable to swap out anonymous pages (potentially anonymous transparent hugepages) in order to create new transparent hugepages. This is true for the MADV_HUGEPAGE areas too (swapping out a kvm virtual machine and so having it suffer an unbearable slowdown, so another one with guest physical memory marked MADV_HUGEPAGE can run 30% faster if it is running memory intensive workloads, makes no sense). If a transparent hugepage allocation fails the slowdown is minor and there is total fallback, so kswapd should never be asked to swapout memory to allow the high order allocation to succeed. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6e62d5f9d40b..bbd0423f2820 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2027,7 +2027,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
2027 goto nopage; 2027 goto nopage;
2028 2028
2029restart: 2029restart:
2030 wake_all_kswapd(order, zonelist, high_zoneidx, 2030 if (!(gfp_mask & __GFP_NO_KSWAPD))
2031 wake_all_kswapd(order, zonelist, high_zoneidx,
2031 zone_idx(preferred_zone)); 2032 zone_idx(preferred_zone));
2032 2033
2033 /* 2034 /*