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Subject: Re: [memcg] 0f12156dff: will-it-scale.per_process_ops -33.6%
 regression
To:     kernel test robot <oliver.sang@intel.com>,
        Vasily Averin <vvs@virtuozzo.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Shakeel Butt <shakeelb@google.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Andrei Vagin <avagin@gmail.com>,
        Borislav Petkov <bp@alien8.de>, Borislav Petkov <bp@suse.de>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        Jeff Layton <jlayton@kernel.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Kirill Tkhai <ktkhai@virtuozzo.com>,
        Michal Hocko <mhocko@kernel.org>,
        Oleg Nesterov <oleg@redhat.com>, Roman Gushchin <guro@fb.com>,
        Serge Hallyn <serge@hallyn.com>, Tejun Heo <tj@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Yutian Yang <nglaive@gmail.com>,
        Zefan Li <lizefan.x@bytedance.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>, lkp@lists.01.org,
        lkp@intel.com, ying.huang@intel.com, feng.tang@intel.com,
        zhengjun.xing@linux.intel.com
References: <20210907150757.GE17617@xsang-OptiPlex-9020>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <dbc9955d-6c28-1dd5-b842-ef39a762aa3b@kernel.dk>
Date:   Tue, 7 Sep 2021 09:46:48 -0600
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On 9/7/21 9:07 AM, kernel test robot wrote:
> 
> 
> Greeting,
> 
> FYI, we noticed a -33.6% regression of will-it-scale.per_process_ops due to commit:
> 
> 
> commit: 0f12156dff2862ac54235fc72703f18770769042 ("memcg: enable accounting for file lock caches")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

Are we at all worried about these? There's been a number of them
reported, basically for all the accounting enablements that have been
done in this merge window.

When io_uring was switched to use accounted memory, we did a bunch of
work to ameliorate the inevitable slowdowns that happen if you do
repeated allocs and/or frees and have memcg accounting enabled.

-- 
Jens Axboe