Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210907150757.GE17617@xsang-OptiPlex-9020> <dbc9955d-6c28-1dd5-b842-ef39a762aa3b@kernel.dk>
In-Reply-To: <dbc9955d-6c28-1dd5-b842-ef39a762aa3b@kernel.dk>
From:   Shakeel Butt <shakeelb@google.com>
Date:   Tue, 7 Sep 2021 08:57:42 -0700
Message-ID: <CALvZod6S+NmG8+-ftS-w3t3zJg_kbr3-F9h-n4jwSnqh0jTUGQ@mail.gmail.com>
Subject: Re: [memcg] 0f12156dff: will-it-scale.per_process_ops -33.6% regression
To:     Jens Axboe <axboe@kernel.dk>
Cc:     kernel test robot <oliver.sang@intel.com>,
        Vasily Averin <vvs@virtuozzo.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        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,
        kernel test robot <lkp@intel.com>,
        Huang Ying <ying.huang@intel.com>,
        Feng Tang <feng.tang@intel.com>,
        Xing Zhengjun <zhengjun.xing@linux.intel.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Sep 7, 2021 at 8:46 AM Jens Axboe <axboe@kernel.dk> wrote:
>
> 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.
>

I think these are important and we should aim to continuously improve
performance with memcg accounting. I would like to know more about the
io_uring work done to improve memcg accounting. Maybe we can
generalize it to others as well.