From: Tejun Heo <tj@kernel.org>
To: Zefan Li <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
cgroups@vger.kernel.org, mingo@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem
Date: Thu, 21 May 2015 16:39:43 -0400 [thread overview]
Message-ID: <20150521203943.GS24861@htj.duckdns.org> (raw)
In-Reply-To: <555C5C71.80200@huawei.com>
Hello, Li.
On Wed, May 20, 2015 at 06:05:37PM +0800, Zefan Li wrote:
> > The latency is bound by synchronize_sched_expedited(). Given the way
> > cgroups are used in majority of setups (process migration happening
> > only during service / session setups), I think this should be okay.
>
> Actually process migration can happen quite frequently, for example in
> Android phones, and that's why Google had an out-of-tree patch to remove
> the synchronize_rcu() in that path, which turned out to be buggy.
It's still not a very frequent operation tho. We're talking about
users switching fore/background jobs here and the expedited
synchronization w/ preemption enabled doesn't take much time. In
addition, as it currently stands, android is doing memory charge
immigration on each fore/background switches. I'm pretty doubtful
this would make any difference.
Thanks.
--
tejun
next prev parent reply other threads:[~2015-05-21 20:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-13 20:35 [PATCHSET] cgroup, sched: restructure threadgroup locking and replace it with a percpu_rwsem Tejun Heo
2015-05-13 20:35 ` [PATCH 1/3] sched, cgroup: reorganize threadgroup locking Tejun Heo
2015-05-14 1:09 ` Sergey Senozhatsky
2015-05-14 15:17 ` Tejun Heo
2015-05-13 20:35 ` [PATCH 2/3] sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem Tejun Heo
2015-05-19 15:16 ` Peter Zijlstra
2015-05-19 15:51 ` Tejun Heo
2015-05-20 10:05 ` Zefan Li
2015-05-21 20:39 ` Tejun Heo [this message]
2015-05-24 2:35 ` Zefan Li
2015-05-13 20:35 ` [PATCH 3/3] cgroup: simplify threadgroup locking Tejun Heo
2015-05-18 16:34 ` [PATCHSET] cgroup, sched: restructure threadgroup locking and replace it with a percpu_rwsem Tejun Heo
2015-05-18 20:06 ` Peter Zijlstra
2015-05-27 0:34 ` Tejun Heo
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=20150521203943.GS24861@htj.duckdns.org \
--to=tj@kernel.org \
--cc=cgroups@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lizefan@huawei.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®