From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Lai Jiangshan <laijs@cn.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
Anton Blanchard <anton@au1.ibm.com>,
Tim Pepper <lnxninja@linux.vnet.ibm.com>
Subject: Re: [RFC PATCH 15/15] nohz_task: Procfs interface
Date: Tue, 21 Dec 2010 15:26:43 +0100 [thread overview]
Message-ID: <20101221142641.GI1750@nowhere> (raw)
In-Reply-To: <1292919280.5021.203.camel@laptop>
On Tue, Dec 21, 2010 at 09:14:40AM +0100, Peter Zijlstra wrote:
> On Tue, 2010-12-21 at 02:24 +0100, Frederic Weisbecker wrote:
> >
> > > Also, I'm not quite happy with the pure userspace restriction, but at
> > > least I see why you did that event though you didn't mention that.
> >
> > What do you mean? The fact that kernel threads can not be nohz task?
>
> No, that you key off kernel/user boundary transitions. Arguably one
> could allow simply system calls and page-faults to happen without
> restarting the tick
This is what I do.
> then again, RCU is very pervasive these days so I'm
> not quite sure you can actually make that happen.
No it looks ok. If we entered the kernel and the tick is stopped, we
just exit the extended quiescent state from rcu point of view.
But because we don't tick, we don't notify quiescent state and
so rcu might notice an extended grace period. Then it will
send us the IPI that will make us restart the tick to make us
notifying quiescent states.
next prev parent reply other threads:[~2010-12-21 14:26 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-20 15:24 [RFC PATCH 00/15] Nohz task support Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 01/15] nohz_task: New mask for cpus having nohz task Frederic Weisbecker
2010-12-24 8:00 ` Lai Jiangshan
2010-12-24 8:19 ` Dario Faggioli
2010-12-24 12:29 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 02/15] nohz_task: Avoid nohz task cpu as non-idle timer target Frederic Weisbecker
2010-12-20 15:47 ` Peter Zijlstra
2010-12-20 16:06 ` Steven Rostedt
2010-12-20 16:12 ` Peter Zijlstra
2010-12-21 0:20 ` Frederic Weisbecker
2010-12-21 7:51 ` Peter Zijlstra
2010-12-21 13:58 ` Frederic Weisbecker
2010-12-21 0:13 ` Frederic Weisbecker
2010-12-21 7:50 ` Peter Zijlstra
2010-12-21 13:52 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 03/15] nohz_task: Make tick stop and restart callable outside idle Frederic Weisbecker
2010-12-20 15:48 ` Peter Zijlstra
2010-12-20 16:19 ` Steven Rostedt
2010-12-20 16:25 ` Peter Zijlstra
2010-12-21 1:34 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 04/15] nohz_task: Stop the tick when the nohz task runs alone Frederic Weisbecker
2010-12-20 15:51 ` Peter Zijlstra
2010-12-20 23:37 ` Frederic Weisbecker
2010-12-21 7:35 ` Peter Zijlstra
2010-12-21 13:22 ` Frederic Weisbecker
2010-12-21 14:34 ` Steven Rostedt
2010-12-21 15:14 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 05/15] nohz_task: Restart the tick when another task compete on the cpu Frederic Weisbecker
2010-12-20 15:53 ` Peter Zijlstra
2010-12-20 23:39 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 06/15] nohz_task: Keep the tick if rcu needs it Frederic Weisbecker
2010-12-20 15:58 ` Peter Zijlstra
2010-12-20 23:49 ` Frederic Weisbecker
2010-12-21 0:12 ` Jonathan Corbet
2010-12-21 2:10 ` Frederic Weisbecker
2010-12-21 8:10 ` Paul E. McKenney
2010-12-20 15:24 ` [RFC PATCH 07/15] nohz_task: Restart tick when RCU forces nohz task cpu quiescent state Frederic Weisbecker
2010-12-20 16:02 ` Peter Zijlstra
2010-12-20 23:52 ` Frederic Weisbecker
2010-12-21 7:41 ` Peter Zijlstra
2010-12-21 13:28 ` Frederic Weisbecker
2010-12-21 15:35 ` Paul E. McKenney
2010-12-20 15:24 ` [RFC PATCH 08/15] smp: Don't warn if irq are disabled but we don't wait for the ipi Frederic Weisbecker
2010-12-20 16:03 ` Peter Zijlstra
2010-12-21 0:02 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 09/15] rcu: Make rcu_enter,exit_nohz() callable from irq Frederic Weisbecker
2010-12-21 19:26 ` Paul E. McKenney
2010-12-21 19:27 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 10/15] nohz_task: Enter in extended quiescent state when in userspace Frederic Weisbecker
2010-12-20 16:18 ` Peter Zijlstra
2010-12-21 1:27 ` Frederic Weisbecker
2010-12-21 8:04 ` Peter Zijlstra
2010-12-21 14:06 ` Frederic Weisbecker
2010-12-21 19:28 ` Paul E. McKenney
2010-12-21 21:49 ` Frederic Weisbecker
2010-12-22 2:20 ` Paul E. McKenney
2010-12-20 15:24 ` [RFC PATCH 11/15] x86: Nohz task support Frederic Weisbecker
2010-12-20 16:23 ` Peter Zijlstra
2010-12-21 1:30 ` Frederic Weisbecker
2010-12-21 8:05 ` Peter Zijlstra
2010-12-21 14:19 ` Frederic Weisbecker
2010-12-21 15:12 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 12/15] clocksource: Ignore nohz task cpu in clocksource watchdog Frederic Weisbecker
2010-12-20 16:27 ` Peter Zijlstra
2010-12-21 1:40 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 13/15] sched: Protect nohz task cpu affinity Frederic Weisbecker
2010-12-20 16:28 ` Peter Zijlstra
2010-12-20 17:05 ` Steven Rostedt
2010-12-21 1:55 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 14/15] nohz_task: Clear nohz task attribute on exit() Frederic Weisbecker
2010-12-20 16:30 ` Peter Zijlstra
2010-12-21 1:48 ` Frederic Weisbecker
2010-12-21 8:07 ` Peter Zijlstra
2010-12-21 14:22 ` Frederic Weisbecker
2010-12-20 15:24 ` [RFC PATCH 15/15] nohz_task: Procfs interface Frederic Weisbecker
2010-12-20 15:42 ` Peter Zijlstra
2010-12-20 15:57 ` Frederic Weisbecker
2010-12-20 16:16 ` Peter Zijlstra
2010-12-21 1:24 ` Frederic Weisbecker
2010-12-21 8:14 ` Peter Zijlstra
2010-12-21 14:00 ` Avi Kivity
2010-12-21 17:05 ` Frederic Weisbecker
2010-12-21 18:17 ` Avi Kivity
2010-12-21 21:08 ` Frederic Weisbecker
2010-12-22 9:22 ` Avi Kivity
2010-12-22 9:51 ` Peter Zijlstra
2010-12-22 20:41 ` Frederic Weisbecker
2010-12-21 14:26 ` Frederic Weisbecker [this message]
2010-12-20 15:44 ` [RFC PATCH 00/15] Nohz task support Steven Rostedt
2010-12-20 23:33 ` Frederic Weisbecker
2010-12-21 1:36 ` Steven Rostedt
2010-12-21 2:15 ` Frederic Weisbecker
2010-12-21 7:34 ` Peter Zijlstra
2010-12-21 13:13 ` Frederic Weisbecker
2010-12-21 13:56 ` Avi Kivity
2010-12-21 17:01 ` Frederic Weisbecker
2010-12-20 16:35 ` Peter Zijlstra
2010-12-21 1:53 ` Frederic Weisbecker
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