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From: Chris Metcalf <cmetcalf@mellanox.com>
To: Christoph Lameter <cl@linux.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>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	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>,
	<linux-doc@vger.kernel.org>, <linux-api@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v13 00/12] support "task_isolation" mode
Date: Fri, 22 Jul 2016 08:50:44 -0400	[thread overview]
Message-ID: <7a3f66f7-5011-7d59-2e0e-f57e4e42e6b6@mellanox.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1607212118210.12213@east.gentwo.org>

On 7/21/2016 10:20 PM, Christoph Lameter wrote:
> On Thu, 21 Jul 2016, Chris Metcalf wrote:
>> On 7/20/2016 10:04 PM, Christoph Lameter wrote:
>> unstable, and then scheduling work to safely remove that timer.
>> I haven't looked at this code before (in kernel/time/clocksource.c
>> under CONFIG_CLOCKSOURCE_WATCHDOG) since the timers on
>> arm64 and tile aren't unstable.  Is it possible to boot your machine
>> with a stable clocksource?
> It already as a stable clocksource. Sorry but that was one of the criteria
> for the server when we ordered them. Could this be clock adjustments?

We probably need to get clock folks to jump in on this thread!

Maybe it's disabling some built-in unstable clock just as part of
falling back to using the better, stable clock that you also have?
So maybe there's a way of just disabling that clocksource from the
get-go instead of having it be marked unstable later.

If you run the test again after this storm of unstable marking, does
it all happen again?  Or is it a persistent state in the kernel?
If so, maybe you can just arrange to get to that state before starting
your application's task-isolation code.

Or, if you think it's clock adjustments, perhaps running your test with
ntpd disabled would make it work better?

-- 
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com

WARNING: multiple messages have this Message-ID (diff)
From: Chris Metcalf <cmetcalf@mellanox.com>
To: Christoph Lameter <cl@linux.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>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	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>,
	linux-doc@vger.kernel.org, linux-api@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v13 00/12] support "task_isolation" mode
Date: Fri, 22 Jul 2016 08:50:44 -0400	[thread overview]
Message-ID: <7a3f66f7-5011-7d59-2e0e-f57e4e42e6b6@mellanox.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1607212118210.12213@east.gentwo.org>

On 7/21/2016 10:20 PM, Christoph Lameter wrote:
> On Thu, 21 Jul 2016, Chris Metcalf wrote:
>> On 7/20/2016 10:04 PM, Christoph Lameter wrote:
>> unstable, and then scheduling work to safely remove that timer.
>> I haven't looked at this code before (in kernel/time/clocksource.c
>> under CONFIG_CLOCKSOURCE_WATCHDOG) since the timers on
>> arm64 and tile aren't unstable.  Is it possible to boot your machine
>> with a stable clocksource?
> It already as a stable clocksource. Sorry but that was one of the criteria
> for the server when we ordered them. Could this be clock adjustments?

We probably need to get clock folks to jump in on this thread!

Maybe it's disabling some built-in unstable clock just as part of
falling back to using the better, stable clock that you also have?
So maybe there's a way of just disabling that clocksource from the
get-go instead of having it be marked unstable later.

If you run the test again after this storm of unstable marking, does
it all happen again?  Or is it a persistent state in the kernel?
If so, maybe you can just arrange to get to that state before starting
your application's task-isolation code.

Or, if you think it's clock adjustments, perhaps running your test with
ntpd disabled would make it work better?

-- 
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com


  reply	other threads:[~2016-07-22 14:24 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 [this message]
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
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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