From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Josh Boyer <jwboyer@redhat.com>
Cc: linux-kernel@vger.kernel.org, kernel-team@fedoraproject.org
Subject: Re: RCU related performance regression in 3.3
Date: Wed, 4 Apr 2012 14:36:33 -0700 [thread overview]
Message-ID: <20120404213633.GI2302@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120404152726.GB16299@zod.bos.redhat.com>
On Wed, Apr 04, 2012 at 11:27:27AM -0400, Josh Boyer wrote:
> Hi Paul,
>
> We've had a few reports of some boot slowdowns with the 3.3 rebase we
> did in Fedora 16. One of our users volunteered to bisect a vanilla
> kernel and wound up at "rcu: Permit dyntick-idle with callbacks pending
> (commit 7cb924990)". You can find more details in the bug [1], but it's
> been reported on both physical hardware and in virtual machines.
>
> Have you seen anything like this in your testing? Given the user used a
> vanilla 3.3 kernel, I'm wondering if there is a targetted fix that might
> be backported. If so, it would be good to get that headed to the 3.3.y
> stable tree.
>
> josh
>
> [1] https://bugzilla.redhat.com/show_bug.cgi?id=806548
I will look into this. In the meantime, does setting
CONFIG_RCU_FAST_NO_HZ=n get rid of the slowdowns?
Thanx, Paul
next prev parent reply other threads:[~2012-04-04 21:36 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-04 15:27 RCU related performance regression in 3.3 Josh Boyer
2012-04-04 21:36 ` Paul E. McKenney [this message]
2012-04-05 12:37 ` Josh Boyer
2012-04-05 14:00 ` Paul E. McKenney
2012-04-05 14:15 ` Pascal CHAPPERON
2012-04-05 14:39 ` Paul E. McKenney
2012-04-06 9:18 ` Pascal Chapperon
2012-04-10 16:07 ` Paul E. McKenney
2012-04-11 15:06 ` Pascal
2012-04-12 18:04 ` Paul E. McKenney
2012-04-16 21:02 ` Paul E. McKenney
2012-04-18 9:37 ` Pascal Chapperon
2012-04-18 14:01 ` Paul E. McKenney
2012-04-18 15:00 ` Pascal Chapperon
2012-04-18 15:23 ` Paul E. McKenney
2012-04-20 14:45 ` Pascal Chapperon
-- strict thread matches above, loose matches on Subject: below --
2012-04-27 12:15 Pascal Chapperon
2012-04-28 3:42 ` Paul E. McKenney
2012-05-01 0:02 ` Paul E. McKenney
2012-05-01 8:55 ` Pascal Chapperon
2012-05-01 15:45 ` Paul E. McKenney
2012-05-04 14:42 ` Pascal Chapperon
2012-05-04 15:04 ` Paul E. McKenney
2012-05-04 21:41 ` Pascal Chapperon
2012-05-04 23:14 ` Paul E. McKenney
2012-05-10 8:40 ` Pascal Chapperon
2012-05-14 22:32 ` Paul E. McKenney
2012-05-18 11:01 ` Pascal Chapperon
2012-05-18 12:14 ` Paul E. McKenney
2012-05-18 14:48 ` Pascal Chapperon
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