linux-kernel - Re: [PATCH RFC 1/2] mm: kmem: optimize get_obj_cgroup_from

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Date:   Tue, 20 Dec 2022 13:15:16 -0800
From:   Roman Gushchin <roman.gushchin@...ux.dev>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     linux-mm@...ck.org, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Muchun Song <muchun.song@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH RFC 1/2] mm: kmem: optimize get_obj_cgroup_from_current()

On Tue, Dec 20, 2022 at 11:55:34AM -0800, Shakeel Butt wrote:
> On Tue, Dec 20, 2022 at 10:28 AM Roman Gushchin
> <roman.gushchin@...ux.dev> wrote:
> >
> > Manually inline memcg_kmem_bypass() and active_memcg() to speed up
> > get_obj_cgroup_from_current() by avoiding duplicate in_task() checks
> > and active_memcg() readings.
> >
> > Also add a likely() macro to __get_obj_cgroup_from_memcg():
> > obj_cgroup_tryget() should succeed at almost all times except
> > a very unlikely race with the memcg deletion path.
> >
> > Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>
> 
> Can you please add your performance experiment setup and result of
> this patch in the commit description of this patch as well?

Sure. I used a small hack to just do a bunch of allocations in a raw
and measured the time. Will include it into the commit message.

Also will fix the #ifdef thing from the second patch, thanks for spotting
it.

> 
> Acked-by: Shakeel Butt <shakeelb@...gle.com>

Thank you for taking a look!