linux-kernel - Re: [memcg] 45208c9105: aim7.jobs-per-min -14.0% regression

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Message-ID: <20210907033000.GA88160@shbuild999.sh.intel.com>
Date:   Tue, 7 Sep 2021 11:30:00 +0800
From:   Feng Tang <feng.tang@...el.com>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     kernel test robot <oliver.sang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        0day robot <lkp@...el.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Hillf Danton <hdanton@...a.com>,
        Huang Ying <ying.huang@...el.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Michal Koutn?? <mkoutny@...e.com>,
        Muchun Song <songmuchun@...edance.com>,
        Roman Gushchin <guro@...com>, Tejun Heo <tj@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
        Xing Zhengjun <zhengjun.xing@...ux.intel.com>,
        Linux MM <linux-mm@...ck.org>, mm-commits@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [memcg] 45208c9105: aim7.jobs-per-min -14.0% regression

Hi Shakeel, 

On Sun, Sep 05, 2021 at 03:15:46PM -0700, Shakeel Butt wrote:
> On Sun, Sep 5, 2021 at 5:27 AM kernel test robot <oliver.sang@...el.com> wrote:
[...]
> > =========================================================================================
> > compiler/cpufreq_governor/disk/fs/kconfig/load/rootfs/tbox_group/test/testcase/ucode:
> >   gcc-9/performance/1BRD_48G/xfs/x86_64-rhel-8.3/3000/debian-10.4-x86_64-20200603.cgz/lkp-icl-2sp2/disk_rr/aim7/0xd000280
> >
> > commit:
> >   3c28c7680e ("memcg: switch lruvec stats to rstat")
> >   45208c9105 ("memcg: infrastructure to flush memcg stats")
> 
> I am looking into this. I was hoping we have resolution for [1] as
> these patches touch similar data structures.
> 
> [1] https://lore.kernel.org/all/20210811031734.GA5193@xsang-OptiPlex-9020/T/#u

I tried 2 debug methods for that 36.4% vm-scalability regression:

1. Disable the HW cache prefetcher, no effect on this case 
2. relayout and add padding to 'struct cgroup_subsys_state', reduce
   the regression to 3.1%

Thanks,
Feng