Messages in this thread Patch in this message | | | From | KOSAKI Motohiro <> | Subject | Re: Free memory never fully used, swapping | Date | Thu, 25 Nov 2010 19:18:49 +0900 (JST) |
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> There are actually a few problems here. I think they are worth looking > at them separately, unless "don't use order 3 allocations" is a valid > statement, in which case we should fix slub. > > The funny thing here is that slub.c's allocate_slab() calls alloc_pages() > with flags | __GFP_NOWARN | __GFP_NORETRY, and intentionally tries a > lower order allocation automatically if it fails. This is why there is > no allocation failure warning when this happens. However, it is too late > -- kswapd is woken and it ties to bring order 3 up to the watermark. > If we hacked __alloc_pages_slowpath() to not wake kswapd when > __GFP_NOWARN is set, we would never see this problem and the slub > optimization might still mostly work. Either way, we should "fix" slub > or "fix" order-3 allocations, so that other people who are using slub > don't hit the same problem.
This?
Subject: [PATCH] slub: use no __GFP_WAIT instead __GFP_NORETRY
--- mm/slub.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c index 8c66aef..0c77399 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1134,7 +1134,7 @@ 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_NOFAIL; + alloc_gfp = (flags | __GFP_NOWARN) & ~(__GFP_NOFAIL | __GFP_WAIT); page = alloc_slab_page(alloc_gfp, node, oo); if (unlikely(!page)) { -- 1.6.5.2
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