From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Christoph Lameter <cl@linux.com>,
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: Thu, 11 Aug 2016 09:00:27 -0700 [thread overview]
Message-ID: <20160811160027.GV3482@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160811084002.GV30192@twins.programming.kicks-ass.net>
On Thu, Aug 11, 2016 at 10:40:02AM +0200, Peter Zijlstra wrote:
> On Thu, Aug 11, 2016 at 12:16:58AM +0200, Frederic Weisbecker wrote:
> > I had similar issues, this seems to happen when the tsc is considered not reliable
> > (which doesn't necessarily mean unstable. I think it has to do with some x86 CPU feature
> > flag).
>
> Right, as per the other email, in general we cannot know/assume the TSC
> to be working as intended :/
>
> > IIRC, this _has_ to execute on all online CPUs because every TSCs of running CPUs
> > are concerned.
>
> With modern Intel we could run it on one CPU per package I think, but at
> the same time, too much in NOHZ_FULL assumes the TSC is indeed sane so
> it doesn't make sense to me to keep the watchdog running, when it
> triggers it would also have to kill all NOHZ_FULL stuff, which would
> probably bring the entire machine down..
Well, you -could- force a very low priority CPU-bound task to run on
all nohz_full CPUs. Not necessarily a good idea, but a relatively
non-intrusive response to that particular error condition.
Thanx, Paul
> Arguably we should issue a boot time warning if NOHZ_FULL is configured
> and the TSC watchdog is running.
>
> > I personally override that with passing the tsc=reliable kernel
> > parameter. Of course use it at your own risk.
>
> Yes, that is (sadly) our only option. Manually assert our hardware is
> solid under the intended workload and then manually disabling the
> watchdog.
>
next prev parent reply other threads:[~2016-08-11 22:29 UTC|newest]
Thread overview: 48+ 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 ` [PATCH v13 03/12] lru_add_drain_all: factor out lru_add_drain_needed Chris Metcalf
2016-07-14 20:48 ` [PATCH v13 04/12] task_isolation: add initial support 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 ` [PATCH v13 08/12] arch/arm64: enable task isolation functionality 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 21:22 ` Chris Metcalf
2016-07-18 22:11 ` Andy Lutomirski
2016-07-18 22:50 ` Chris Metcalf
2016-07-18 0:42 ` Christoph Lameter
2016-07-21 2:04 ` Christoph Lameter
2016-07-21 14:06 ` Chris Metcalf
2016-07-22 2:20 ` Christoph Lameter
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 14:12 ` Chris Metcalf
2016-07-27 15:23 ` Christoph Lameter
2016-07-27 15:31 ` Christoph Lameter
2016-07-27 17:06 ` Chris Metcalf
2016-07-27 18:56 ` Christoph Lameter
2016-07-27 19:49 ` Chris Metcalf
2016-07-27 19:53 ` Christoph Lameter
2016-07-27 19:58 ` Chris Metcalf
2016-07-29 18:31 ` Francis Giraldeau
2016-07-29 21:04 ` Chris Metcalf
2016-08-10 22:16 ` Frederic Weisbecker
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
2016-08-11 16:00 ` Paul E. McKenney [this message]
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 16:19 ` Paul E. McKenney
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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