From: Chris Metcalf <cmetcalf@mellanox.com>
To: Christoph Lameter <cl@linux.com>,
Frederic Weisbecker <fweisbec@gmail.com>
Cc: Gilad Ben Yossef <giladb@mellanox.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Rik van Riel" <riel@redhat.com>, Tejun Heo <tj@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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>,
"Francis Giraldeau" <francis.giraldeau@gmail.com>,
<linux-doc@vger.kernel.org>, <linux-api@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Fix /proc/stat freezes (was [PATCH v15] "task_isolation" mode)
Date: Fri, 19 Aug 2016 21:42:19 -0400 [thread overview]
Message-ID: <427287c8-3fa8-093c-29ac-d492a88a6337@mellanox.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1608171432200.30568@east.gentwo.org>
On 8/17/2016 3:37 PM, Christoph Lameter wrote:
> On Tue, 16 Aug 2016, Chris Metcalf wrote:
>
>> - Dropped Christoph Lameter's patch to avoid scheduling the
>> clocksource watchdog on nohz cores; the recommendation is to just
>> boot with tsc=reliable for NOHZ in any case, if necessary.
> We also said that there should be a WARN_ON if tsc=reliable is not
> specified and processors are put into NOHZ mode. This is something not
> obvious causing scheduling events on NOHZ processors.
Yes, I agree. Frederic said he would queue a patch to do that, so I
didn't want to propose another patch that would conflict.
>> Frederic, do you have a sense of what is left to be done there?
>> I can certainly try to contribute to that effort as well.
> Here is a potential fix to the problem that /proc/stat values freeze when
> processors go into NOHZ busy mode. I'd like to hear what people think
> about the approach here. In particular one issue may be that I am
> accessing remote tick-sched structures without serialization. But for
> top/ps this may be ok. I noticed that other values shown by top/os also
> sometime are a bit fuzzy.
This seems pretty plausible to me, but I'm not an expert on what kind
of locking might be required for these data structures.
--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com
next prev parent reply other threads:[~2016-08-20 8:18 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-16 21:19 [PATCH v15 00/13] support "task_isolation" mode Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 01/13] vmstat: add quiet_vmstat_sync function Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 02/13] vmstat: add vmstat_idle function Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 03/13] lru_add_drain_all: factor out lru_add_drain_needed Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 04/13] task_isolation: add initial support Chris Metcalf
2016-08-29 16:33 ` Peter Zijlstra
2016-08-29 16:40 ` Chris Metcalf
2016-08-29 16:48 ` Peter Zijlstra
2016-08-29 16:53 ` Chris Metcalf
2016-08-30 7:59 ` Peter Zijlstra
2016-08-30 7:58 ` Peter Zijlstra
2016-08-30 15:32 ` Chris Metcalf
2016-08-30 16:30 ` Andy Lutomirski
2016-08-30 17:02 ` Chris Metcalf
2016-08-30 18:43 ` Andy Lutomirski
2016-08-30 19:37 ` Chris Metcalf
2016-08-30 19:50 ` Andy Lutomirski
2016-09-02 14:04 ` Chris Metcalf
2016-09-02 17:28 ` Andy Lutomirski
2016-09-09 17:40 ` Chris Metcalf
2016-09-12 17:41 ` Andy Lutomirski
2016-09-12 19:25 ` Chris Metcalf
2016-09-27 14:22 ` Frederic Weisbecker
2016-09-27 14:39 ` Peter Zijlstra
2016-09-27 14:51 ` Frederic Weisbecker
2016-09-27 14:48 ` Paul E. McKenney
2016-09-30 16:59 ` Chris Metcalf
2016-09-01 10:06 ` Peter Zijlstra
2016-09-02 14:03 ` Chris Metcalf
2016-09-02 16:40 ` Peter Zijlstra
2017-02-02 16:13 ` Eugene Syromiatnikov
2017-02-02 18:12 ` Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 05/13] task_isolation: track asynchronous interrupts Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 06/13] arch/x86: enable task isolation functionality Chris Metcalf
2016-08-30 21:46 ` Andy Lutomirski
2016-08-16 21:19 ` [PATCH v15 07/13] arm64: factor work_pending state machine to C Chris Metcalf
2016-08-17 8:05 ` Will Deacon
2016-08-16 21:19 ` [PATCH v15 08/13] arch/arm64: enable task isolation functionality Chris Metcalf
2016-08-26 16:25 ` Catalin Marinas
2016-08-16 21:19 ` [PATCH v15 09/13] arch/tile: " Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 10/13] arm, tile: turn off timer tick for oneshot_stopped state Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 11/13] task_isolation: support CONFIG_TASK_ISOLATION_ALL Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 12/13] task_isolation: add user-settable notification signal Chris Metcalf
2016-08-16 21:19 ` [PATCH v15 13/13] task_isolation self test Chris Metcalf
2016-08-17 19:37 ` [PATCH] Fix /proc/stat freezes (was [PATCH v15] "task_isolation" mode) Christoph Lameter
2016-08-20 1:42 ` Chris Metcalf [this message]
2016-09-28 13:16 ` Frederic Weisbecker
2016-08-29 16:27 ` Ping: [PATCH v15 00/13] support "task_isolation" mode Chris Metcalf
2016-09-07 21:11 ` Francis Giraldeau
2016-09-07 21:39 ` Francis Giraldeau
2016-09-08 16:21 ` Francis Giraldeau
2016-09-12 16:01 ` Chris Metcalf
2016-09-12 16:14 ` Peter Zijlstra
2016-09-12 21:15 ` Rafael J. Wysocki
2016-09-13 0:05 ` Rafael J. Wysocki
2016-09-13 16:00 ` Francis Giraldeau
2016-09-13 0:20 ` Francis Giraldeau
2016-09-13 16:12 ` Chris Metcalf
2016-09-27 14:49 ` Frederic Weisbecker
2016-09-27 14:35 ` Frederic Weisbecker
2016-09-30 17:07 ` Chris Metcalf
2016-11-05 4:04 ` task isolation discussion at Linux Plumbers Chris Metcalf
2016-11-05 16:05 ` Christoph Lameter
2016-11-07 16:55 ` Thomas Gleixner
2016-11-07 18:36 ` Thomas Gleixner
2016-11-07 19:12 ` Rik van Riel
2016-11-07 19:16 ` Will Deacon
2016-11-07 19:18 ` Rik van Riel
2016-11-11 20:54 ` Luiz Capitulino
2016-11-09 1:40 ` Paul E. McKenney
2016-11-09 11:14 ` Andy Lutomirski
2016-11-09 17:38 ` Paul E. McKenney
2016-11-09 18:57 ` Will Deacon
2016-11-09 19:11 ` Paul E. McKenney
2016-11-10 1:44 ` Andy Lutomirski
2016-11-10 4:52 ` Paul E. McKenney
2016-11-10 5:10 ` Paul E. McKenney
2016-11-11 17:00 ` Andy Lutomirski
2016-11-09 11:07 ` Frederic Weisbecker
2016-12-19 14:37 ` Paul E. McKenney
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