Messages in this thread | | | Date | Tue, 20 Nov 2012 13:49:32 -0800 | From | Andrew Morton <> | Subject | Re: [patch] mm, memcg: avoid unnecessary function call when memcg is disabled |
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On Mon, 19 Nov 2012 17:44:34 -0800 (PST) David Rientjes <rientjes@google.com> wrote:
> 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. > > ... > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -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() || !mm) > + return; > + __mem_cgroup_count_vm_event(mm, idx); > +}
Does the !mm case occur frequently enough to justify inlining it, or should that test remain out-of-line?
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