Messages in this thread | | | Date | Thu, 28 Jan 2016 13:43:13 -0500 (EST) | From | Jan Stancek <> | Subject | Re: [BUG] scheduler doesn't balance thread to idle cpu for 3 seconds |
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----- Original Message ----- > 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 > Sent: Thursday, 28 January, 2016 6:49:03 PM > Subject: Re: [BUG] scheduler doesn't balance thread to idle cpu for 3 seconds > > 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.
I can try that too. I'm mostly seeing this on s390 and x86_64 KVM guests, both have 2 CPUs.
Have you noticed if iteration times vary or if they stay consitently at ~2 seconds?
> > 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.
Regards, Jan
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