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
-- strict thread matches above, loose matches on Subject: below --
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
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=4EBD522E.2000203@parallels.com \
--to=xemul@parallels.com \
--cc=akpm@linux-foundation.org \
--cc=dlezcano@fr.ibm.com \
--cc=glommer@parallels.com \
--cc=gorcunov@openvz.org \
--cc=linux-kernel@vger.kernel.org \
--cc=ntl@pobox.com \
--cc=oleg@redhat.com \
--cc=serue@us.ibm.com \
--cc=tj@kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.