linux-kernel - Re: [LKP] Re: [mm/memcg] bd0b230fe1: will-it-scale.per_process

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Date:   Mon, 2 Nov 2020 11:02:47 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Rong Chen <rong.a.chen@...el.com>
Cc:     Waiman Long <longman@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Chris Down <chris@...isdown.name>,
        Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <guro@...com>, Tejun Heo <tj@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Yafang Shao <laoar.shao@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
        lkp@...el.com, zhengjun.xing@...el.com
Subject: Re: [LKP] Re: [mm/memcg] bd0b230fe1: will-it-scale.per_process_ops
 -22.7% regression

On Mon 02-11-20 17:53:14, Rong Chen wrote:
> 
> 
> On 11/2/20 5:27 PM, Michal Hocko wrote:
> > On Mon 02-11-20 17:15:43, kernel test robot wrote:
> > > Greeting,
> > > 
> > > FYI, we noticed a -22.7% regression of will-it-scale.per_process_ops due to commit:
> > > 
> > > 
> > > commit: bd0b230fe14554bfffbae54e19038716f96f5a41 ("mm/memcg: unify swap and memsw page counters")
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > I really fail to see how this can be anything else than a data structure
> > layout change. There is one counter less.
> > 
> > btw. are cgroups configured at all? What would be the configuration?
> 
> Hi Michal,
> 
> We used the default configure of cgroups, not sure what configuration you
> want,
> could you give me more details? and here is the cgroup info of will-it-scale
> process:
> 
> $ cat /proc/3042/cgroup
> 12:hugetlb:/
> 11:memory:/system.slice/lkp-bootstrap.service

OK, this means that memory controler is enabled and in use. Btw. do you
get the original performance if you add one phony page_counter after the
union?
-- 
Michal Hocko
SUSE Labs