Re: [RFC PATCH 10/11] torture: support randomized shuffling for proxy exec testing

From: "Connor O'Brien" <connoro@google.com>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
	John Stultz <jstultz@google.com>,
	Qais Yousef <qais.yousef@arm.com>, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	"Paul E . McKenney" <paulmck@kernel.org>
Subject: Re: [RFC PATCH 10/11] torture: support randomized shuffling for proxy exec testing
Date: Mon, 14 Nov 2022 12:44:21 -0800	[thread overview]
Message-ID: <CALE1s+Ox_RF81kgF0YeV7sbuBN3RbBEvSK9_z6T4uWW2U_q=RQ@mail.gmail.com> (raw)
In-Reply-To: <Y2/P3cMExRt2fUP5@google.com>

> Instead of doing it this way, maybe another approach is to randomize the
> sleep interval in:
>
>  */
> static int torture_shuffle(void *arg)
> {
>         VERBOSE_TOROUT_STRING("torture_shuffle task started");
>         do {
>                 schedule_timeout_interruptible(shuffle_interval);
>                 torture_shuffle_tasks();
>                 ...
>         } while (...)
>         ...
> }
>
> Right now with this patch you still wakeup the shuffle thread when skipping
> the affinity set operation.
>
> thanks,
>
>  - Joel
>

Wouldn't the affinities of all the tasks still change in lockstep
then? The intent with this patch is to get into situations where the
tasks have different affinity masks, which I think requires changing
the behavior of torture_shuffle_tasks() rather than how often it's
called.