linux-kernel - Re: [memcg] 0f12156dff: will-it-scale.per_process

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Message-ID: <CALvZod6S+NmG8+-ftS-w3t3zJg_kbr3-F9h-n4jwSnqh0jTUGQ@mail.gmail.com>
Date:   Tue, 7 Sep 2021 08:57:42 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     kernel test robot <oliver.sang@...el.com>,
        Vasily Averin <vvs@...tuozzo.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Andrei Vagin <avagin@...il.com>,
        Borislav Petkov <bp@...en8.de>, Borislav Petkov <bp@...e.de>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Jeff Layton <jlayton@...nel.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Michal Hocko <mhocko@...nel.org>,
        Oleg Nesterov <oleg@...hat.com>, Roman Gushchin <guro@...com>,
        Serge Hallyn <serge@...lyn.com>, Tejun Heo <tj@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Yutian Yang <nglaive@...il.com>,
        Zefan Li <lizefan.x@...edance.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
        kernel test robot <lkp@...el.com>,
        Huang Ying <ying.huang@...el.com>,
        Feng Tang <feng.tang@...el.com>,
        Xing Zhengjun <zhengjun.xing@...ux.intel.com>
Subject: Re: [memcg] 0f12156dff: will-it-scale.per_process_ops -33.6% regression

On Tue, Sep 7, 2021 at 8:46 AM Jens Axboe <axboe@...nel.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.