From: Michal Hocko <mhocko@suse.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Vasily Averin <vvs@virtuozzo.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
kernel@openvz.org, Cgroups <cgroups@vger.kernel.org>
Subject: Re: [PATCH] ipc: remove memcg accounting for sops objects in do_semtimedop()
Date: Tue, 14 Sep 2021 09:13:48 +0200 [thread overview]
Message-ID: <YUBLrJOL6DGxmira@dhcp22.suse.cz> (raw)
In-Reply-To: <CALvZod7Y4pC4XvqVp+tJ==CnS5Ay8YPqrxeUzA8tMLu+0U3hjQ@mail.gmail.com>
On Mon 13-09-21 21:32:25, Shakeel Butt wrote:
> On Mon, Sep 13, 2021 at 1:37 AM Michal Hocko <mhocko@suse.com> wrote:
> >
> [...]
> > > However Shakeel Butt pointed that there are much more popular objects
> > > with the same life time and similar memory consumption, the accounting
> > > of which was decided to be rejected for performance reasons.
> >
> > Is there any measurable performance impact in this particular case?
> >
>
> I don't think there was any regression report or any performance
> evaluation. Linus raised the concern on the potential performance
> impact. I suggested to backoff for this allocation for now and revisit
> again once we have improved the memcg accounting for kernel memory.
I am fine with the change, I am just not satisfied with the
justification. It is not really clear what the intention is except that
Linus wanted it. I have already asked Vasily to provide more
explanation. E.g. this part really begs for clarification
"
This object can consume up to 2 pages, syscall is sleeping one,
size and duration can be controlled by user, and this allocation
can be repeated by many thread at the same time.
"
It sounds like a problem, except it is not because? A worst case
scenario evaluation would be beneficial for example
Thanks!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-09-14 7:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-11 7:40 [PATCH] ipc: remove memcg accounting for sops objects in do_semtimedop() Vasily Averin
2021-09-12 16:05 ` Shakeel Butt
2021-09-13 8:37 ` Michal Hocko
2021-09-14 4:32 ` Shakeel Butt
2021-09-14 7:13 ` Michal Hocko [this message]
2021-09-14 14:23 ` Michal Koutný
2021-09-14 14:32 ` Michal Hocko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YUBLrJOL6DGxmira@dhcp22.suse.cz \
--to=mhocko@suse.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=hannes@cmpxchg.org \
--cc=kernel@openvz.org \
--cc=linux-kernel@vger.kernel.org \
--cc=shakeelb@google.com \
--cc=torvalds@linux-foundation.org \
--cc=vvs@virtuozzo.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).