From: Glauber Costa <glommer@parallels.com>
To: David Miller <davem@davemloft.net>
Cc: <linux-kernel@vger.kernel.org>, <akpm@linux-foundation.org>,
<lizf@cn.fujitsu.com>, <kamezawa.hiroyu@jp.fujitsu.com>,
<ebiederm@xmission.com>, <paul@paulmenage.org>,
<gthelen@google.com>, <netdev@vger.kernel.org>,
<linux-mm@kvack.org>, <kirill@shutemov.name>,
<avagin@parallels.com>, <devel@openvz.org>
Subject: Re: [PATCH v7 0/8] Request for inclusion: tcp memory buffers
Date: Fri, 14 Oct 2011 00:14:40 +0400 [thread overview]
Message-ID: <4E9746B0.7030603@parallels.com> (raw)
In-Reply-To: <20111013.161221.1969725742975317077.davem@davemloft.net>
On 10/14/2011 12:12 AM, David Miller wrote:
> From: Glauber Costa<glommer@parallels.com>
> Date: Fri, 14 Oct 2011 00:05:58 +0400
>
>> Also, I kind of dispute the affirmation that !cgroup will encompass
>> the majority of users, since cgroups is being enabled by default by
>> most vendors. All systemd based systems use it extensively, for
>> instance.
>
> I will definitely advise people against this, since the cost of having
> this on by default is absolutely non-trivial.
>
> People keep asking every few releases "where the heck has my performance
> gone" and it's because of creeping features like this. This socket
> cgroup feature is a prime example of where that kind of stuff comes
> from.
>
> I really get irritated when people go "oh, it's just one indirect
> function call" and "oh, it's just one more pointer in struct sock"
>
> We work really hard to _remove_ elements from structures and make them
> smaller, and to remove expensive operations from the fast paths.
>
> It might take someone weeks if not months to find a way to make a
> patch which compensates for the extra overhead your patches are adding.
>
> And I don't think you fully appreciate that.
Let's focus on this:
Are you happy, or at least willing to accept, an approach that keep
things as they were with cgroups *compiled out*, or were you referring
to not in use == compiled in, but with no users?
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next prev parent reply other threads:[~2011-10-13 20:14 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-13 13:09 [PATCH v7 0/8] Request for inclusion: tcp memory buffers Glauber Costa
2011-10-13 13:09 ` [PATCH v7 1/8] Basic kernel memory functionality for the Memory Controller Glauber Costa
2011-10-13 13:09 ` [PATCH v7 2/8] socket: initial cgroup code Glauber Costa
2011-10-13 13:09 ` [PATCH v7 3/8] foundations of per-cgroup memory pressure controlling Glauber Costa
2011-10-13 13:09 ` [PATCH v7 4/8] per-cgroup tcp buffers control Glauber Costa
2011-10-13 13:09 ` [PATCH v7 5/8] per-netns ipv4 sysctl_tcp_mem Glauber Costa
2011-10-13 13:09 ` [PATCH v7 6/8] tcp buffer limitation: per-cgroup limit Glauber Costa
2011-10-13 13:09 ` [PATCH v7 7/8] Display current tcp memory allocation in kmem cgroup Glauber Costa
2011-10-13 13:09 ` [PATCH v7 8/8] Disable task moving when using kernel memory accounting Glauber Costa
2011-10-13 20:00 ` [PATCH v7 0/8] Request for inclusion: tcp memory buffers David Miller
2011-10-13 20:05 ` Glauber Costa
2011-10-13 20:08 ` David Miller
2011-10-13 20:12 ` David Miller
2011-10-13 20:14 ` Glauber Costa [this message]
2011-10-13 20:18 ` David Miller
2011-10-14 12:56 ` Glauber Costa
2011-10-19 21:09 ` David Miller
2011-10-13 20:16 ` David Miller
2011-10-13 20:23 ` Glauber Costa
2011-10-14 2:55 ` Valdis.Kletnieks
2011-10-14 2:12 ` Andi Kleen
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