From 4518085e127dff97e74f74a8780d7564e273bec8 Mon Sep 17 00:00:00 2001 From: Kemi Wang Date: Wed, 15 Nov 2017 17:38:22 -0800 Subject: mm, sysctl: make NUMA stats configurable This is the second step which introduces a tunable interface that allow numa stats configurable for optimizing zone_statistics(), as suggested by Dave Hansen and Ying Huang. ========================================================================= When page allocation performance becomes a bottleneck and you can tolerate some possible tool breakage and decreased numa counter precision, you can do: echo 0 > /proc/sys/vm/numa_stat In this case, numa counter update is ignored. We can see about *4.8%*(185->176) drop of cpu cycles per single page allocation and reclaim on Jesper's page_bench01 (single thread) and *8.1%*(343->315) drop of cpu cycles per single page allocation and reclaim on Jesper's page_bench03 (88 threads) running on a 2-Socket Broadwell-based server (88 threads, 126G memory). Benchmark link provided by Jesper D Brouer (increase loop times to 10000000): https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/mm/bench ========================================================================= When page allocation performance is not a bottleneck and you want all tooling to work, you can do: echo 1 > /proc/sys/vm/numa_stat This is system default setting. Many thanks to Michal Hocko, Dave Hansen, Ying Huang and Vlastimil Babka for comments to help improve the original patch. [keescook@chromium.org: make sure mutex is a global static] Link: http://lkml.kernel.org/r/20171107213809.GA4314@beast Link: http://lkml.kernel.org/r/1508290927-8518-1-git-send-email-kemi.wang@intel.com Signed-off-by: Kemi Wang Signed-off-by: Kees Cook Reported-by: Jesper Dangaard Brouer Suggested-by: Dave Hansen Suggested-by: Ying Huang Acked-by: Vlastimil Babka Acked-by: Michal Hocko Cc: "Luis R . Rodriguez" Cc: Kees Cook Cc: Jonathan Corbet Cc: Mel Gorman Cc: Johannes Weiner Cc: Christopher Lameter Cc: Sebastian Andrzej Siewior Cc: Andrey Ryabinin Cc: Tim Chen Cc: Andi Kleen Cc: Aaron Lu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mempolicy.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mm/mempolicy.c') diff --git a/mm/mempolicy.c b/mm/mempolicy.c index dad166b736ba..4ce44d3ff03d 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1915,6 +1915,9 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order, struct page *page; page = __alloc_pages(gfp, order, nid); + /* skip NUMA_INTERLEAVE_HIT counter update if numa stats is disabled */ + if (!static_branch_likely(&vm_numa_stat_key)) + return page; if (page && page_to_nid(page) == nid) { preempt_disable(); __inc_numa_state(page_zone(page), NUMA_INTERLEAVE_HIT); -- cgit v1.2.3-55-g7522