From: Frederic Weisbecker <fweisbec@gmail.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>,
Peter Zijlstra <peterz@infradead.org>,
Chris Metcalf <cmetcalf@mellanox.com>,
Gilad Ben Yossef <giladb@mellanox.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Viresh Kumar <viresh.kumar@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Andy Lutomirski <luto@amacapital.net>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
linux-doc@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: clocksource_watchdog causing scheduling of timers every second (was [v13] support "task_isolation" mode)
Date: Sat, 13 Aug 2016 17:39:45 +0200 [thread overview]
Message-ID: <20160813153942.GB21154@lerouge> (raw)
In-Reply-To: <20160812161919.GV3482@linux.vnet.ibm.com>
On Fri, Aug 12, 2016 at 09:19:19AM -0700, Paul E. McKenney wrote:
> On Fri, Aug 12, 2016 at 04:26:13PM +0200, Frederic Weisbecker wrote:
> > On Fri, Aug 12, 2016 at 09:23:13AM -0500, Christoph Lameter wrote:
> > > On Thu, 11 Aug 2016, Paul E. McKenney wrote:
> > >
> > > > Heh! The only really good idea is for clocks to be reliably in sync.
> > > >
> > > > But if they go out of sync, what do you want to do instead?
> > >
> > > For a NOHZ task? Write a message to the syslog and reenable tick.
>
> Fair enough! Kicking off a low-priority task would achieve the latter
> but not necessarily the former. And of course assumes that the worker
> thread is at real-time priority with various scheduler anti-starvation
> features disabled.
>
> > Indeed, a strong clocksource is a requirement for a full tickless machine.
>
> No disagrement here! ;-)
I have a bot in my mind that randomly posts obvious statements about nohz_full
here and then :-)
WARNING: multiple messages have this Message-ID (diff)
From: Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: "Paul E. McKenney"
<paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
Cc: Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>,
Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
Chris Metcalf <cmetcalf-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
Gilad Ben Yossef <giladb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
Steven Rostedt <rostedt-nx8X9YLhiw1AfugRpC6u6w@public.gmane.org>,
Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Rik van Riel <riel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
Viresh Kumar
<viresh.kumar-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>,
Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>,
Daniel Lezcano
<daniel.lezcano-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: clocksource_watchdog causing scheduling of timers every second (was [v13] support "task_isolation" mode)
Date: Sat, 13 Aug 2016 17:39:45 +0200 [thread overview]
Message-ID: <20160813153942.GB21154@lerouge> (raw)
In-Reply-To: <20160812161919.GV3482-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
On Fri, Aug 12, 2016 at 09:19:19AM -0700, Paul E. McKenney wrote:
> On Fri, Aug 12, 2016 at 04:26:13PM +0200, Frederic Weisbecker wrote:
> > On Fri, Aug 12, 2016 at 09:23:13AM -0500, Christoph Lameter wrote:
> > > On Thu, 11 Aug 2016, Paul E. McKenney wrote:
> > >
> > > > Heh! The only really good idea is for clocks to be reliably in sync.
> > > >
> > > > But if they go out of sync, what do you want to do instead?
> > >
> > > For a NOHZ task? Write a message to the syslog and reenable tick.
>
> Fair enough! Kicking off a low-priority task would achieve the latter
> but not necessarily the former. And of course assumes that the worker
> thread is at real-time priority with various scheduler anti-starvation
> features disabled.
>
> > Indeed, a strong clocksource is a requirement for a full tickless machine.
>
> No disagrement here! ;-)
I have a bot in my mind that randomly posts obvious statements about nohz_full
here and then :-)
next prev parent reply other threads:[~2016-08-13 15:39 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 20:48 [PATCH v13 00/12] support "task_isolation" mode Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 01/12] vmstat: add quiet_vmstat_sync function Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 02/12] vmstat: add vmstat_idle function Chris Metcalf
2016-07-14 20:48 ` Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 03/12] lru_add_drain_all: factor out lru_add_drain_needed Chris Metcalf
2016-07-14 20:48 ` Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 04/12] task_isolation: add initial support Chris Metcalf
2016-07-14 20:48 ` Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 05/12] task_isolation: track asynchronous interrupts Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 06/12] arch/x86: enable task isolation functionality Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 07/12] arm64: factor work_pending state machine to C Chris Metcalf
2016-07-14 20:48 ` Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 08/12] arch/arm64: enable task isolation functionality Chris Metcalf
2016-07-14 20:48 ` Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 09/12] arch/tile: " Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 10/12] arm, tile: turn off timer tick for oneshot_stopped state Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 11/12] task_isolation: support CONFIG_TASK_ISOLATION_ALL Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 12/12] task_isolation: add user-settable notification signal Chris Metcalf
2016-07-14 21:03 ` [PATCH v13 00/12] support "task_isolation" mode Andy Lutomirski
2016-07-14 21:03 ` Andy Lutomirski
2016-07-14 21:22 ` Chris Metcalf
2016-07-14 21:22 ` Chris Metcalf
2016-07-18 22:11 ` Andy Lutomirski
2016-07-18 22:50 ` Chris Metcalf
2016-07-18 0:42 ` Christoph Lameter
2016-07-18 0:42 ` Christoph Lameter
2016-07-21 2:04 ` Christoph Lameter
2016-07-21 2:04 ` Christoph Lameter
2016-07-21 14:06 ` Chris Metcalf
2016-07-21 14:06 ` Chris Metcalf
2016-07-22 2:20 ` Christoph Lameter
2016-07-22 12:50 ` Chris Metcalf
2016-07-22 12:50 ` Chris Metcalf
2016-07-25 16:35 ` Christoph Lameter
2016-07-27 13:55 ` clocksource_watchdog causing scheduling of timers every second (was [v13] support "task_isolation" mode) Christoph Lameter
2016-07-27 13:55 ` Christoph Lameter
2016-07-27 14:12 ` Chris Metcalf
2016-07-27 14:12 ` Chris Metcalf
2016-07-27 15:23 ` Christoph Lameter
2016-07-27 15:23 ` Christoph Lameter
2016-07-27 15:31 ` Christoph Lameter
2016-07-27 15:31 ` Christoph Lameter
2016-07-27 17:06 ` Chris Metcalf
2016-07-27 17:06 ` Chris Metcalf
2016-07-27 18:56 ` Christoph Lameter
2016-07-27 19:49 ` Chris Metcalf
2016-07-27 19:49 ` Chris Metcalf
2016-07-27 19:53 ` Christoph Lameter
2016-07-27 19:58 ` Chris Metcalf
2016-07-27 19:58 ` Chris Metcalf
2016-07-29 18:31 ` Francis Giraldeau
2016-07-29 18:31 ` Francis Giraldeau
2016-07-29 21:04 ` Chris Metcalf
2016-07-29 21:04 ` Chris Metcalf
2016-08-10 22:16 ` Frederic Weisbecker
2016-08-10 22:26 ` Chris Metcalf
2016-08-10 22:26 ` Chris Metcalf
2016-08-11 8:40 ` Peter Zijlstra
2016-08-11 11:58 ` Frederic Weisbecker
2016-08-15 15:03 ` Chris Metcalf
2016-08-15 15:03 ` Chris Metcalf
2016-08-11 16:00 ` Paul E. McKenney
2016-08-11 23:02 ` Christoph Lameter
2016-08-11 23:47 ` Paul E. McKenney
2016-08-12 14:23 ` Christoph Lameter
2016-08-12 14:26 ` Frederic Weisbecker
2016-08-12 14:26 ` Frederic Weisbecker
2016-08-12 16:19 ` Paul E. McKenney
2016-08-13 15:39 ` Frederic Weisbecker [this message]
2016-08-13 15:39 ` Frederic Weisbecker
2016-08-11 8:27 ` [PATCH v13 00/12] support "task_isolation" mode Peter Zijlstra
2016-07-27 14:01 ` Christoph Lameter
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