Messages in this thread Patch in this message | | | From | Alex Shi <> | Subject | [PATCH] mm: correct page->pfmemalloc to fix deactivate_slab regression | Date | Mon, 13 Aug 2012 20:14:35 +0800 |
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commit cfd19c5a9ec (mm: only set page->pfmemalloc when ALLOC_NO_WATERMARKS was used) try 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 has 40% regression.
This patch move the checking in get_page_from_freelist, that resolved this issue.
Signed-off-by: Alex Shi <alex.shi@intel.com> --- mm/page_alloc.c | 21 +++++++++++---------- 1 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 009ac28..07f1924 100644 --- a/mm/page_alloc.c +++ b/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); -- 1.7.5.4
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