pull in some SLUB fixes from Mel Gorman for testing

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
+
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