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author | Kyle McMartin <kyle@redhat.com> | 2011-05-11 16:20:10 -0400 |
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committer | Kyle McMartin <kyle@redhat.com> | 2011-05-11 16:20:16 -0400 |
commit | a7e4f1ccd5f84c722b5f69e08488294e2f875509 (patch) | |
tree | 1263894fd528cf278cdb6f5da1025052161a1a97 /mm-slub-do-not-take-expensive-steps-for-slubs-speculative-high-order-allocations.patch | |
parent | 9b1caead9ae2dfa0652653fb1026567a71bcbf55 (diff) | |
download | kernel-a7e4f1ccd5f84c722b5f69e08488294e2f875509.tar.gz kernel-a7e4f1ccd5f84c722b5f69e08488294e2f875509.tar.xz kernel-a7e4f1ccd5f84c722b5f69e08488294e2f875509.zip |
pull in some SLUB fixes from Mel Gorman for testing
Diffstat (limited to 'mm-slub-do-not-take-expensive-steps-for-slubs-speculative-high-order-allocations.patch')
-rw-r--r-- | mm-slub-do-not-take-expensive-steps-for-slubs-speculative-high-order-allocations.patch | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/mm-slub-do-not-take-expensive-steps-for-slubs-speculative-high-order-allocations.patch b/mm-slub-do-not-take-expensive-steps-for-slubs-speculative-high-order-allocations.patch new file mode 100644 index 000000000..70191d54b --- /dev/null +++ b/mm-slub-do-not-take-expensive-steps-for-slubs-speculative-high-order-allocations.patch @@ -0,0 +1,73 @@ +From owner-linux-mm@kvack.org Wed May 11 11:29:53 2011 +From: Mel Gorman <mgorman@suse.de> +To: Andrew Morton <akpm@linux-foundation.org> +Subject: [PATCH 2/3] mm: slub: Do not take expensive steps for SLUBs speculative high-order allocations +Date: Wed, 11 May 2011 16:29:32 +0100 +Message-Id: <1305127773-10570-3-git-send-email-mgorman@suse.de> + +To avoid locking and per-cpu overhead, SLUB optimisically uses +high-order allocations and falls back to lower allocations if they +fail. However, by simply trying to allocate, the caller can enter +compaction or reclaim - both of which are likely to cost more than the +benefit of using high-order pages in SLUB. On a desktop system, two +users report that the system is getting stalled with kswapd using large +amounts of CPU. + +This patch prevents SLUB taking any expensive steps when trying to +use high-order allocations. Instead, it is expected to fall back to +smaller orders more aggressively. Testing from users was somewhat +inconclusive on how much this helped but local tests showed it made +a positive difference. It makes sense that falling back to order-0 +allocations is faster than entering compaction or direct reclaim. + +Signed-off-yet: Mel Gorman <mgorman@suse.de> +--- + mm/page_alloc.c | 3 ++- + mm/slub.c | 3 ++- + 2 files changed, 4 insertions(+), 2 deletions(-) + +diff --git a/mm/page_alloc.c b/mm/page_alloc.c +index 9f8a97b..057f1e2 100644 +--- a/mm/page_alloc.c ++++ b/mm/page_alloc.c +@@ -1972,6 +1972,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask) + { + int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET; + const gfp_t wait = gfp_mask & __GFP_WAIT; ++ const gfp_t can_wake_kswapd = !(gfp_mask & __GFP_NO_KSWAPD); + + /* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */ + BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH); +@@ -1984,7 +1985,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask) + */ + alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH); + +- if (!wait) { ++ if (!wait && can_wake_kswapd) { + /* + * Not worth trying to allocate harder for + * __GFP_NOMEMALLOC even if it can't schedule. +diff --git a/mm/slub.c b/mm/slub.c +index 98c358d..1071723 100644 +--- a/mm/slub.c ++++ b/mm/slub.c +@@ -1170,7 +1170,8 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) + * Let the initial higher-order allocation fail under memory pressure + * so we fall-back to the minimum order allocation. + */ +- alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY | __GFP_NO_KSWAPD) & ~__GFP_NOFAIL; ++ alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY | __GFP_NO_KSWAPD) & ++ ~(__GFP_NOFAIL | __GFP_WAIT); + + page = alloc_slab_page(alloc_gfp, node, oo); + if (unlikely(!page)) { +-- +1.7.3.4 + +-- +To unsubscribe, send a message with 'unsubscribe linux-mm' in +the body to majordomo@kvack.org. For more info on Linux MM, +see: http://www.linux-mm.org/ . +Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ +Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> + |