On Mon 19-11-12 17:44:34, David Rientjes 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.
>
> Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Thanks!
> ---
> include/linux/memcontrol.h | 9 ++++++++-
> mm/memcontrol.c | 9 ++++-----
> 2 files changed, 12 insertions(+), 6 deletions(-)
>
> 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);
> +}
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> void mem_cgroup_split_huge_fixup(struct page *head);
> #endif
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -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;
>
> @@ -1015,13 +1017,10 @@ 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;
>
> - if (!mm)
> - return;
> -
> rcu_read_lock();
> memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
> if (unlikely(!memcg))
> @@ -1040,7 +1039,7 @@ 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
> --
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--
Michal Hocko
SUSE Labs
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