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: clocksource_watchdog causing scheduling of timers every second (was [v13] support "task_isolation" mode)
Date: Wed, 27 Jul 2016 13:06:08 -0400 [thread overview]
Message-ID: <f7553d2a-f4ab-b218-bb93-fcb436db1770@mellanox.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1607271030020.25729@east.gentwo.org>
On 7/27/2016 11:31 AM, Christoph Lameter wrote:
> Ok here is a possible patch that explicitly checks for housekeeping cpus:
>
> Subject: clocksource: Do not schedule watchdog on isolated or NOHZ cpus
>
> watchdog checks can only run on housekeeping capable cpus. Otherwise
> we will be generating noise that we would like to avoid on the isolated
> processors.
>
> Signed-off-by: Christoph Lameter <cl@linux.com>
>
> Index: linux/kernel/time/clocksource.c
> ===================================================================
> --- linux.orig/kernel/time/clocksource.c 2016-07-27 08:41:17.109862517 -0500
> +++ linux/kernel/time/clocksource.c 2016-07-27 10:28:31.172447732 -0500
> @@ -269,9 +269,12 @@ static void clocksource_watchdog(unsigne
> * Cycle through CPUs to check if the CPUs stay synchronized
> * to each other.
> */
> - next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
> - if (next_cpu >= nr_cpu_ids)
> - next_cpu = cpumask_first(cpu_online_mask);
> + do {
> + next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
> + if (next_cpu >= nr_cpu_ids)
> + next_cpu = cpumask_first(cpu_online_mask);
> + } while (!is_housekeeping_cpu(next_cpu));
> +
> watchdog_timer.expires += WATCHDOG_INTERVAL;
> add_timer_on(&watchdog_timer, next_cpu);
> out:
How about using cpumask_next_and(raw_smp_processor_id(), cpu_online_mask,
housekeeping_cpumask()), likewise cpumask_first_and()? Does that work?
Note that you should also cpumask_first_and() in clocksource_start_watchdog(),
just to be complete.
Hopefully the init code runs after tick_init(). It seems like that's probably true.
--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com
next prev parent reply other threads:[~2016-07-27 17:06 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 [this message]
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
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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