Re: Possible regression due to "tick: broadcast: Prevent livelock from event handler"

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: Possible regression due to "tick: broadcast: Prevent livelock from event handler"
Date	2015-07-03 16:20 +0200
Message-ID	<pI9YS-17f-9@gated-at.bofh.it> (permalink)
References	<pHZd7-2Kt-1@gated-at.bofh.it> <pI6Rk-7tK-5@gated-at.bofh.it> <pI9cu-AJ-7@gated-at.bofh.it> <pI9ma-E1-31@gated-at.bofh.it>
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On Fri, 3 Jul 2015, Wolfram Sang wrote:

> 
> > So with high res timers it boots. Can you please provide the output of
> > /proc/timer_list for that case?

> Tick Device: mode:     1
> Per CPU device: 0
> Clock Event Device: e0180000.timer
>  max_delta_ns:   131071523464982
>  min_delta_ns:   61035
>  mult:           70369
>  shift:          31
>  mode:           3
>  next_event:     40760000000 nsecs
>  set_next_event: em_sti_clock_event_next
>  set_mode:       em_sti_clock_event_mode
>  event_handler:  hrtimer_interrupt
>  retries:        0

So this is a single core machine and uses the em_sti timer w/o the
broadcast nonsense. In Simons case it looks like em_sti is used as
broadcast device.

Though the issues you see in the highres=n case might be the same as
the ones Simon is observing.

So in that nohz=y highres=n case, does adding idle=poll on the command
line fix the issue?

Thanks,

	tglx
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Thread

Possible regression due to "tick: broadcast: Prevent livelock from  event handler" Simon Horman <horms@verge.net.au> - 2015-07-03 04:50 +0200
  Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Thomas Gleixner <tglx@linutronix.de> - 2015-07-03 11:30 +0200
  Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Wolfram Sang <wsa@the-dreams.de> - 2015-07-03 13:00 +0200
    Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-07-03 13:10 +0200
    Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Thomas Gleixner <tglx@linutronix.de> - 2015-07-03 15:30 +0200
      Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Wolfram Sang <wsa@the-dreams.de> - 2015-07-03 15:40 +0200
        Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Thomas Gleixner <tglx@linutronix.de> - 2015-07-03 16:20 +0200
          Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Wolfram Sang <wsa@the-dreams.de> - 2015-07-03 16:40 +0200
            Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Sudeep Holla <sudeep.holla@arm.com> - 2015-07-03 16:50 +0200
              Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Sudeep Holla <sudeep.holla@arm.com> - 2015-07-03 17:00 +0200
              Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Thomas Gleixner <tglx@linutronix.de> - 2015-07-03 17:00 +0200
            Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Thomas Gleixner <tglx@linutronix.de> - 2015-07-03 17:00 +0200
              Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Wolfram Sang <wsa@the-dreams.de> - 2015-07-03 17:20 +0200
                Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Thomas Gleixner <tglx@linutronix.de> - 2015-07-03 17:30 +0200
                Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Wolfram Sang <wsa@the-dreams.de> - 2015-07-03 17:50 +0200
                Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Thomas Gleixner <tglx@linutronix.de> - 2015-07-03 18:00 +0200
                Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Wolfram Sang <wsa@the-dreams.de> - 2015-07-03 18:10 +0200
            Re: Possible regression due to "tick: broadcast: Prevent livelock  from event handler" Geert Uytterhoeven <geert@linux-m68k.org> - 2015-07-03 19:10 +0200

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