From: Pavel Emelyanov <xemul@parallels.com>
To: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Glauber Costa <glommer@parallels.com>,
Nathan Lynch <ntl@pobox.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Serge Hallyn <serue@us.ibm.com>,
Daniel Lezcano <dlezcano@fr.ibm.com>
Subject: Re: [PATCH 3/3] pids: Make it possible to clone tasks with given pids
Date: Fri, 11 Nov 2011 20:49:50 +0400 [thread overview]
Message-ID: <4EBD522E.2000203@parallels.com> (raw)
In-Reply-To: <20111111162200.GA24737@google.com>
On 11/11/2011 08:22 PM, Tejun Heo wrote:
> On Fri, Nov 11, 2011 at 08:18:19PM +0400, Pavel Emelyanov wrote:
>>> To add a bit, it's also one of the more *serialized* path. Doing it in
>>> parallel might actually hurt,
>>
>> Can you elaborate on this, please?
>
> It goes through a lot of locks - tasklist_lock, mmlist_lock, other
> subsys locks depending on CLONE_* options. If you try to do that on
> multiple CPUs in parallel, depending on the level of concurrency,
> contention and extra cacheline bounces may dominate the overhead.
O_O Here are the times of forks on my box (4cores X 2threads, Xeon, RHEL6)
1 cpu 500k forks - 37s
2 cpus on different cores 500k forks on each in parallel - 39s
4 cpus on different cores 500k forks on each in parallel - 41s
8 cpus 500k forks on each in parallel - 1m5s
So the fork() scaling seems quite good to me.
> Thanks.
>
next prev parent reply other threads:[~2011-11-11 16:49 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-10 17:15 [PATCH 0/3] Introduce the cloning with pids functionality Pavel Emelyanov
2011-11-10 17:15 ` [PATCH 1/3] pids: Make alloc_pid return error Pavel Emelyanov
2011-11-10 18:00 ` Oleg Nesterov
2011-11-11 10:02 ` Pavel Emelyanov
2011-11-10 17:15 ` [PATCH 2/3] pids: Split alloc_pidmap into parts Pavel Emelyanov
2011-11-10 18:12 ` Oleg Nesterov
2011-11-10 17:16 ` [PATCH 3/3] pids: Make it possible to clone tasks with given pids Pavel Emelyanov
2011-11-10 17:30 ` Tejun Heo
2011-11-10 17:36 ` Pavel Emelyanov
2011-11-10 17:45 ` Tejun Heo
2011-11-11 10:04 ` Pavel Emelyanov
2011-11-10 18:46 ` Oleg Nesterov
2011-11-10 18:56 ` Oleg Nesterov
2011-11-11 10:11 ` Pavel Emelyanov
2011-11-11 15:25 ` Oleg Nesterov
2011-11-11 15:58 ` Pavel Emelyanov
2011-11-11 16:06 ` Tejun Heo
2011-11-11 16:10 ` Tejun Heo
2011-11-11 16:18 ` Pavel Emelyanov
2011-11-11 16:22 ` Tejun Heo
2011-11-11 16:49 ` Pavel Emelyanov [this message]
2011-11-11 17:02 ` Tejun Heo
2011-11-11 17:13 ` Pavel Emelyanov
2011-11-13 19:28 ` Oleg Nesterov
2011-11-14 10:28 ` Pavel Emelyanov
2011-11-11 16:17 ` Pavel Emelyanov
2011-11-11 16:48 ` Oleg Nesterov
2011-11-11 16:39 ` Oleg Nesterov
2011-11-11 16:55 ` Pavel Emelyanov
2011-11-13 18:59 ` Oleg Nesterov
2011-11-17 11:41 [RFC][PATCH 0/3] fork: Add the ability to create " Pavel Emelyanov
2011-11-17 11:43 ` [PATCH 3/3] pids: Make it possible to clone " Pavel Emelyanov
2011-11-17 15:32 ` Oleg Nesterov
2011-11-17 15:49 ` Pavel Emelyanov
2011-11-17 16:00 ` Oleg Nesterov
2011-11-17 17:28 ` Linus Torvalds
2011-11-17 19:04 ` Oleg Nesterov
2011-11-17 18:36 ` Oleg Nesterov
2011-11-18 10:05 ` Pavel Emelyanov
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