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From: Christoph Lameter <cl@linux.com>
To: Chris Metcalf <cmetcalf@mellanox.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 10:31:31 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.20.1607271030020.25729@east.gentwo.org> (raw)
In-Reply-To: <alpine.DEB.2.20.1607271022130.25729@east.gentwo.org>

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:

  reply	other threads:[~2016-07-27 15:31 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 [this message]
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
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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