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Commit 68ae564b authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
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mm, memcg: avoid unnecessary function call when memcg is disabled 



While profiling numa/core v16 with cgroup_disable=memory on the command
line, I noticed mem_cgroup_count_vm_event() still showed up as high as
0.60% in perftop.

This occurs because the function is called extremely often even when memcg
is disabled.

To fix this, inline the check for mem_cgroup_disabled() so we avoid the
unnecessary function call if memcg is disabled.

Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: default avatarGlauber Costa <glommer@parallels.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 05b0afd7

include/linux/memcontrol.h

+8 −1
Original line number Diff line number Diff line
@@ -181,7 +181,14 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, 
						gfp_t gfp_mask,

						unsigned long *total_scanned);



void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);

void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);

static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,

					     enum vm_event_item idx)

{

	if (mem_cgroup_disabled())

		return;

	__mem_cgroup_count_vm_event(mm, idx);

}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

void mem_cgroup_split_huge_fixup(struct page *head);

#endif

mm/memcontrol.c

+4 −2
Original line number Diff line number Diff line
@@ -59,6 +59,8 @@ 
#include <trace/events/vmscan.h>



struct cgroup_subsys mem_cgroup_subsys __read_mostly;

EXPORT_SYMBOL(mem_cgroup_subsys);



#define MEM_CGROUP_RECLAIM_RETRIES	5

static struct mem_cgroup *root_mem_cgroup __read_mostly;
@@ -1015,7 +1017,7 @@ void mem_cgroup_iter_break(struct mem_cgroup *root, 
	     iter != NULL;				\

	     iter = mem_cgroup_iter(NULL, iter, NULL))



void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)

void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)

{

	struct mem_cgroup *memcg;
@@ -1040,7 +1042,7 @@ void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx) 
out:

	rcu_read_unlock();

}

EXPORT_SYMBOL(mem_cgroup_count_vm_event);

EXPORT_SYMBOL(__mem_cgroup_count_vm_event);



/**

 * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg