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From: Peter Zijlstra <peterz@infradead.org>
To: Jan Stancek <jstancek@redhat.com>
Cc: alex shi <alex.shi@intel.com>, guz fnst <guz.fnst@cn.fujitsu.com>,
	mingo@redhat.com, jolsa@redhat.com, riel@redhat.com,
	linux-kernel@vger.kernel.org
Subject: Re: [BUG] scheduler doesn't balance thread to idle cpu for 3 seconds
Date: Fri, 29 Jan 2016 11:15:22 +0100	[thread overview]
Message-ID: <20160129101522.GF6357@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <333246323.13611103.1454006593261.JavaMail.zimbra@redhat.com>

On Thu, Jan 28, 2016 at 01:43:13PM -0500, Jan Stancek wrote:
> > How long should I have to wait for a fail?
> 
> It's about 1000-2000 iterations for me, which I think you covered
> by now in those 2 hours.

So I've been running:

  while ! ./pthread_cond_wait_1 ; do sleep 1; done

overnight on the machine, and have yet to hit a wobbly -- that is, its
still running.

Also note that I don't think failing this test is a bug per se.
Undesirable maybe, but within spec, since SIGALRM is process wide, so it
being delivered to the SCHED_OTHER task is accepted, and SCHED_OTHER has
no timeliness guarantees.

That said; if I could reliably reproduce I'd have a go at fixing this, I
suspect there's a 'fun' problem at the bottom of this.

  reply	other threads:[~2016-01-29 10:15 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-27 14:52 Jan Stancek
2016-01-28 15:55 ` Jan Stancek
2016-01-28 17:49   ` Peter Zijlstra
2016-01-28 18:43     ` Jan Stancek
2016-01-29 10:15       ` Peter Zijlstra [this message]
2016-01-29 10:33         ` Jan Stancek
2016-02-08 13:40           ` Jan Stancek

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