Re: [BUG] scheduler doesn't balance thread to idle cpu for 3 seconds

[Peter Zijlstra]

On Thu, Jan 28, 2016 at 04:55:02PM +0100, Jan Stancek wrote:
> On 01/27/2016 03:52 PM, Jan Stancek wrote:
> > Hello,
> > 
> > pthread_cond_wait_1/2 [1] is rarely failing for me on 4.5.0-rc1,
> > on x86_64 KVM guest with 2 CPUs.
> > 
> > This test [1]:
> > - spawns 2 SCHED_RR threads
> > - first thread with higher priority sets alarm for 2 seconds and blocks on condition
> > - second thread with lower priority is busy looping for 5 seconds
> > - after 2 seconds alarm signal arrives and handler signals condition
> > - high priority thread should resume running
> 
> I have slightly modified testcase, so it will finish immediately when high prio
> thread is done. And also to allow it to compile outside of openposix testsuite.

Yeah, I 'fixed' the testcase too.

So I've had it run for almost 2 hours without a single fail. I've
hot-plugged my cpu count down to 2.

How long should I have to wait for a fail?