Re: [patch 4 14/22] timer: Switch to a non cascading wheel

From	Richard Cochran <richardcochran@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [patch 4 14/22] timer: Switch to a non cascading wheel
Date	2016-08-16 11:00 +0200
Message-ID	<s6Io1-R5-15@gated-at.bofh.it> (permalink)
References	<rR8Pv-419-7@gated-at.bofh.it> <rR8Pw-419-35@gated-at.bofh.it> <s505H-5ym-29@gated-at.bofh.it> <s5oUq-4QH-19@gated-at.bofh.it> <s5q9Q-5PW-9@gated-at.bofh.it>
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On Fri, Aug 12, 2016 at 12:14:11PM -0700, Paul E. McKenney wrote:
> FWIW, I do appear to be seeing more lost wakeups on current mainline
> than on v4.7, but not enough of a difference to get a reliable bisction
> in reasonable time.

We are seeing reproducible hangs* when running Steven's
stress-cpu-hotplug under kvm.  This hang goes back to v4.7 at least.
I couldn't reproduce this with bare metal.  Thomas thought it was a
virtualization issue, not related to the hotplug rework.  He is away
until next week.  Maybe he knows more to say...

To reproduce, run 

   while [ 1 ]; do ./stress-cpu-hotplug ; done

and wait about 20 minutes (or longer).

Thanks,
Richard

* INFO: task cpuhp/7:49 blocked for more than 120 seconds

Thread

Re: [patch 4 14/22] timer: Switch to a non cascading wheel Jouni Malinen <jkmalinen@gmail.com> - 2016-08-11 17:30 +0200
  Re: [PREEMPT-RT] [patch 4 14/22] timer: Switch to a non cascading  wheel rcochran@linutronix.de - 2016-08-11 22:30 +0200
    Re: [PREEMPT-RT] [patch 4 14/22] timer: Switch to a non cascading wheel Jouni Malinen <jkmalinen@gmail.com> - 2016-08-13 11:20 +0200
      Re: [PREEMPT-RT] [patch 4 14/22] timer: Switch to a non cascading  wheel Richard Cochran <richardcochran@gmail.com> - 2016-08-16 11:50 +0200
        Re: [PREEMPT-RT] [patch 4 14/22] timer: Switch to a non cascading wheel Eric Dumazet <edumazet@google.com> - 2016-08-16 16:40 +0200
        Re: [PREEMPT-RT] [patch 4 14/22] timer: Switch to a non cascading  wheel Jouni Malinen <j@w1.fi> - 2016-08-17 11:20 +0200
          Re: [PREEMPT-RT] [patch 4 14/22] timer: Switch to a non cascading  wheel rcochran@linutronix.de - 2016-08-17 11:30 +0200
  Re: [patch 4 14/22] timer: Switch to a non cascading wheel Rik van Riel <riel@redhat.com> - 2016-08-12 20:00 +0200
    Re: [patch 4 14/22] timer: Switch to a non cascading wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-08-12 21:20 +0200
      Re: [patch 4 14/22] timer: Switch to a non cascading wheel Richard Cochran <richardcochran@gmail.com> - 2016-08-16 11:00 +0200
    Re: [patch 4 14/22] timer: Switch to a non cascading wheel Richard Cochran <richardcochran@gmail.com> - 2016-08-16 10:00 +0200

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