From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
paulmck@linux.vnet.ibm.com,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
Arjan van de Ven <arjan@infradead.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Milton Miller <miltonm@bga.com>, "mingo@elte.hu" <mingo@elte.hu>,
Tejun Heo <tj@kernel.org>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Linux PM mailing list <linux-pm@vger.kernel.org>
Subject: Re: CPU Hotplug rework
Date: Mon, 26 Mar 2012 15:38:18 +0200 [thread overview]
Message-ID: <1332769098.16159.111.camel@twins> (raw)
In-Reply-To: <1332767386.23924.75.camel@gandalf.stny.rr.com>
On Mon, 2012-03-26 at 09:09 -0400, Steven Rostedt wrote:
> On Mon, 2012-03-26 at 10:02 +0200, Peter Zijlstra wrote:
> > On Mon, 2012-03-26 at 11:11 +1030, Rusty Russell wrote:
> > > Obviously, having callbacks hanging around until the CPU comes back is
> > > not viable, nor is blocking preempt during the callbacks. Calling
> > > get_online_cpus() is too heavy.
> >
> > -rt has patches (albeit somewhat ugly) to make get_online_cpus() a br
> > style rw-lock.
>
> Unfortunately, -rt still has broken cpu hotplug.
This is still the issue where we take the hotplug lock for write, but
then rely on other threads to complete -- say CPU_DOWN_PREPARE notifiers
doing flush_workqueue(), and the worker kthread needing to acquire the
hotplug lock for read, right?
Yes, that is bothersome, but doesn't hinder the work required to get
get_online_cpus() usably fast, right?
next prev parent reply other threads:[~2012-03-26 13:56 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-19 14:44 CPU Hotplug rework Srivatsa S. Bhat
2012-03-19 14:48 ` Srivatsa S. Bhat
2012-03-20 11:28 ` Peter Zijlstra
2012-04-05 17:39 ` Paul E. McKenney
2012-04-05 17:55 ` Paul E. McKenney
2012-04-05 23:06 ` Paul E. McKenney
2012-04-06 20:15 ` Srivatsa S. Bhat
2012-04-09 16:46 ` Paul E. McKenney
2012-04-10 7:56 ` Nikunj A Dadhania
2012-04-06 19:52 ` Srivatsa S. Bhat
2012-04-09 17:13 ` Paul E. McKenney
2012-04-10 13:41 ` Srivatsa S. Bhat
2012-04-10 15:46 ` Paul E. McKenney
2012-04-10 17:26 ` Srivatsa S. Bhat
2012-04-11 0:09 ` Steven Rostedt
2012-04-11 0:28 ` Paul E. McKenney
2012-04-11 0:37 ` Steven Rostedt
2012-04-11 1:00 ` Paul E. McKenney
2012-04-11 6:02 ` Srivatsa S. Bhat
2012-04-11 12:28 ` Paul E. McKenney
2012-03-19 23:42 ` Rusty Russell
2012-03-20 10:42 ` Peter Zijlstra
2012-03-20 23:00 ` Rusty Russell
2012-03-21 9:01 ` Peter Zijlstra
2012-03-22 4:25 ` Rusty Russell
2012-03-22 22:49 ` Paul E. McKenney
2012-03-23 23:27 ` Rusty Russell
2012-03-24 0:23 ` Paul E. McKenney
2012-03-26 0:41 ` Rusty Russell
2012-03-26 8:02 ` Peter Zijlstra
2012-03-26 13:09 ` Steven Rostedt
2012-03-26 13:38 ` Peter Zijlstra [this message]
2012-03-26 15:22 ` Steven Rostedt
2012-03-26 16:13 ` Peter Zijlstra
2012-03-26 17:05 ` Steven Rostedt
2012-03-26 17:59 ` Peter Zijlstra
2012-03-27 1:32 ` Rusty Russell
2012-03-27 3:05 ` Steven Rostedt
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