Messages in this thread Patch in this message | | | Date | Tue, 21 Aug 2012 08:58:05 -0700 | From | Andrew Morton <> | Subject | Re: regression with poll(2) |
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On Mon, 20 Aug 2012 10:02:05 -0700 Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Mon, Aug 20, 2012 at 2:04 AM, Mel Gorman <mgorman@suse.de> wrote: > > > > Can the following patch be tested please? It is reported to fix an fio > > regression that may be similar to what you are experiencing but has not > > been picked up yet. > > Andrew, is this in your queue, or should I take this directly, or > what? It seems to fix the problem for Eric and Sage, at least.
Yes, I have a copy queued:
From: Alex Shi <alex.shi@intel.com> Subject: mm: correct page->pfmemalloc to fix deactivate_slab regression
cfd19c5a9ec ("mm: only set page->pfmemalloc when ALLOC_NO_WATERMARKS was used") tried to narrow down page->pfmemalloc setting, but it missed some places the pfmemalloc should be set.
So, in __slab_alloc, the unalignment pfmemalloc and ALLOC_NO_WATERMARKS cause incorrect deactivate_slab() on our core2 server:
64.73% fio [kernel.kallsyms] [k] _raw_spin_lock | --- _raw_spin_lock | |---0.34%-- deactivate_slab | __slab_alloc | kmem_cache_alloc | |
That causes our fio sync write performance to have a 40% regression.
Move the checking in get_page_from_freelist() which resolves this issue.
Signed-off-by: Alex Shi <alex.shi@intel.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Tested-by: Sage Weil <sage@inktank.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
mm/page_alloc.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
diff -puN mm/page_alloc.c~mm-correct-page-pfmemalloc-to-fix-deactivate_slab-regression mm/page_alloc.c --- a/mm/page_alloc.c~mm-correct-page-pfmemalloc-to-fix-deactivate_slab-regression +++ a/mm/page_alloc.c @@ -1928,6 +1928,17 @@ this_zone_full: zlc_active = 0; goto zonelist_scan; } + + if (page) + /* + * page->pfmemalloc is set when ALLOC_NO_WATERMARKS was + * necessary to allocate the page. The expectation is + * that the caller is taking steps that will free more + * memory. The caller should avoid the page being used + * for !PFMEMALLOC purposes. + */ + page->pfmemalloc = !!(alloc_flags & ALLOC_NO_WATERMARKS); + return page; } @@ -2389,14 +2400,6 @@ rebalance: zonelist, high_zoneidx, nodemask, preferred_zone, migratetype); if (page) { - /* - * page->pfmemalloc is set when ALLOC_NO_WATERMARKS was - * necessary to allocate the page. The expectation is - * that the caller is taking steps that will free more - * memory. The caller should avoid the page being used - * for !PFMEMALLOC purposes. - */ - page->pfmemalloc = true; goto got_pg; } } @@ -2569,8 +2572,6 @@ retry_cpuset: page = __alloc_pages_slowpath(gfp_mask, order, zonelist, high_zoneidx, nodemask, preferred_zone, migratetype); - else - page->pfmemalloc = false; trace_mm_page_alloc(page, order, gfp_mask, migratetype); _
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