On Mon, 19 Nov 2012 17:44:34 -0800 (PST)
David Rientjes <rientjes@xxxxxxxxxx> 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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