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authorRoman Gushchin <guro@fb.com>2017-09-08 16:13:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-08 18:26:47 -0700
commit475d0487a2adb1718892856078861d430d81fc55 (patch)
tree1c388577bc01fabcd6e477d9b8690f285c3a63f5 /mm
parent3a77d214807c32f900618cee0432feb4f7f99c65 (diff)
download96b-common-475d0487a2adb1718892856078861d430d81fc55.tar.gz
mm: memcontrol: use per-cpu stocks for socket memory uncharging
We've noticed a quite noticeable performance overhead on some hosts with significant network traffic when socket memory accounting is enabled. Perf top shows that socket memory uncharging path is hot: 2.13% [kernel] [k] page_counter_cancel 1.14% [kernel] [k] __sk_mem_reduce_allocated 1.14% [kernel] [k] _raw_spin_lock 0.87% [kernel] [k] _raw_spin_lock_irqsave 0.84% [kernel] [k] tcp_ack 0.84% [kernel] [k] ixgbe_poll 0.83% < workload > 0.82% [kernel] [k] enqueue_entity 0.68% [kernel] [k] __fget 0.68% [kernel] [k] tcp_delack_timer_handler 0.67% [kernel] [k] __schedule 0.60% < workload > 0.59% [kernel] [k] __inet6_lookup_established 0.55% [kernel] [k] __switch_to 0.55% [kernel] [k] menu_select 0.54% libc-2.20.so [.] __memcpy_avx_unaligned To address this issue, the existing per-cpu stock infrastructure can be used. refill_stock() can be called from mem_cgroup_uncharge_skmem() to move charge to a per-cpu stock instead of calling atomic page_counter_uncharge(). To prevent the uncontrolled growth of per-cpu stocks, refill_stock() will explicitly drain the cached charge, if the cached value exceeds CHARGE_BATCH. This allows significantly optimize the load: 1.21% [kernel] [k] _raw_spin_lock 1.01% [kernel] [k] ixgbe_poll 0.92% [kernel] [k] _raw_spin_lock_irqsave 0.90% [kernel] [k] enqueue_entity 0.86% [kernel] [k] tcp_ack 0.85% < workload > 0.74% perf-11120.map [.] 0x000000000061bf24 0.73% [kernel] [k] __schedule 0.67% [kernel] [k] __fget 0.63% [kernel] [k] __inet6_lookup_established 0.62% [kernel] [k] menu_select 0.59% < workload > 0.59% [kernel] [k] __switch_to 0.57% libc-2.20.so [.] __memcpy_avx_unaligned Link: http://lkml.kernel.org/r/20170829100150.4580-1-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 126a939b600a..ca83f3854e4f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1792,6 +1792,9 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
}
stock->nr_pages += nr_pages;
+ if (stock->nr_pages > CHARGE_BATCH)
+ drain_stock(stock);
+
local_irq_restore(flags);
}
@@ -5886,8 +5889,7 @@ void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
this_cpu_sub(memcg->stat->count[MEMCG_SOCK], nr_pages);
- page_counter_uncharge(&memcg->memory, nr_pages);
- css_put_many(&memcg->css, nr_pages);
+ refill_stock(memcg, nr_pages);
}
static int __init cgroup_memory(char *s)