From: Doug Ledford <dledford@redhat.com>
To: Serge Hallyn <serge.hallyn@canonical.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-kernel@vger.kernel.org,
"Dmitry V. Levin" <ldv@altlinux.org>,
Pavel Emelyanov <xemul@openvz.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>
Subject: Re: [RFC, PATCH] CLONE_NEWIPC and exit_group()
Date: Thu, 12 Jul 2012 15:06:40 -0400 [thread overview]
Message-ID: <4FFF2040.1010008@redhat.com> (raw)
In-Reply-To: <20120712185452.GA24342@sergelap>
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On 07/12/2012 02:54 PM, Serge Hallyn wrote:
> Quoting Kirill A. Shutemov (kirill.shutemov@linux.intel.com):
>> On Wed, Jul 11, 2012 at 03:24:22PM -0700, Andrew Morton wrote:
>>> Am I reading that right? 1000 forks take 33 seconds, with basically
>>> all of it just sitting there asleep? This look quite terrible - what
>>> causes this?
>>
>> It seems free_nsproxy() + synchronize_rcu() are too heavy to be in
>> exit_group() path. Patch below helps: 8s -> ~0.5s for me.
>
> And sys time goes down by that much too, or only user time?
>
> Given that, with user namespaces, it'll soon be possible for users who
> are unprivileged toward the host to be able to create and destroy
> namespaces, if the patch ends up making it easy for a user to consume a
> bunch of system time and not have it accounted at all to himself, then
> I think we should keep it as is.
Indeed.
--
Doug Ledford <dledford@redhat.com>
GPG KeyID: 0E572FDD
http://people.redhat.com/dledford
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prev parent reply other threads:[~2012-07-12 19:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-26 12:04 [RFC, PATCH] CLONE_NEWIPC and exit_group() Kirill A. Shutemov
2012-06-26 17:04 ` Serge E. Hallyn
2012-06-26 17:45 ` Kirill A. Shutemov
2012-06-26 17:55 ` Serge E. Hallyn
2012-06-27 12:34 ` Dmitry V. Levin
2012-06-27 13:01 ` Serge Hallyn
2012-07-10 8:50 ` Kirill A. Shutemov
2012-07-11 22:24 ` Andrew Morton
2012-07-12 15:07 ` Kirill A. Shutemov
2012-07-12 18:54 ` Serge Hallyn
2012-07-12 19:06 ` Doug Ledford [this message]
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