From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
Subject: Re: [PATCH RFC] memcg: revert kmem.tcp accounting
Date: Fri, 12 Sep 2014 19:18:09 +0200
Message-ID: <20140912171809.GA24469@dhcp22.suse.cz>
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To: Vladimir Davydov <vdavydov-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>, "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Kamezawa Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>, Glauber Costa <glommer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Pavel Emelianov <xemul-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Eric Dumazet <eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>

On Fri 12-09-14 19:26:58, Vladimir Davydov wrote:
> memory.kmem.tcp.limit_in_bytes works as the system-wide tcp_mem sysctl,
> but per memory cgroup. While the existence of the latter is justified
> (it prevents the system from becoming unusable due to uncontrolled tcp
> buffers growth) the reason why we need such a knob in containers isn't
> clear to me.

Parallels was the primary driver for this change. I haven't heard of
anybody using the feature other than Parallels. I also remember there
was a strong push for this feature before it was merged besides there
were some complains at the time. I do not remember details (and I am
one half way gone for the weekend now) so I do not have pointers to
discussions.

I would love to get rid of the code and I am pretty sure that networking
people would love this go even more. I didn't plan to provide kmem.tcp.*
knobs for the cgroups v2 interface but getting rid of it altogether
sounds even better. I am just not sure whether some additional users
grown over time.
Nevertheless I am really curious. What has changed that Parallels is not
interested in kmem.tcp anymore?

[...]

Anyway, more than welcome
Acked-by: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>

In case we happened to grow more users, which I hope hasn't happened, we
would need to keep this around at least with the legacy cgroups API.
-- 
Michal Hocko
SUSE Labs