From: Frederic Weisbecker <fweisbec@gmail.com>
To: Dario Faggioli <raistlin@linux.it>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@linux-foundation.org>,
Anton Blanchard <anton@au1.ibm.com>,
Tim Pepper <lnxninja@linux.vnet.ibm.com>
Subject: Re: [RFC PATCH 01/15] nohz_task: New mask for cpus having nohz task
Date: Fri, 24 Dec 2010 13:29:14 +0100 [thread overview]
Message-ID: <20101224122903.GA1879@nowhere> (raw)
In-Reply-To: <1293178796.3182.2.camel@Palantir>
On Fri, Dec 24, 2010 at 09:19:56AM +0100, Dario Faggioli wrote:
> On Fri, 2010-12-24 at 16:00 +0800, Lai Jiangshan wrote:
> > On 12/20/2010 11:24 PM, Frederic Weisbecker wrote:
> > >
> > > +config NO_HZ_TASK
> > > + bool "Tickless task"
> > > + depends on HAVE_NO_HZ_TASK && NO_HZ && SMP && HIGH_RES_TIMERS
> > > + help
> > > + When a task runs alone on a CPU and switches into this mode,
> > > + the timer interrupt will only trigger when it is strictly
> > > + needed.
> >
> > Why it depends on SMP?
> >
> I guess that's because you need at least a ticking CPU for timekeeping
> and stuff... Right?
>
> Regards,
> Dario
Exactly.
In the next version I'll probably drop that requirement. On UP a single task
must still be able to be in nohz mode when it is in userspace, as timekeeping
doesn't matter there until we reenter the kernel.
Dunno, I'll see what I can do.
next prev parent reply other threads:[~2010-12-24 12:29 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 [this message]
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
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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