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

Thomas Gleixner tglx at linutronix.de
Fri Jul 3 07:17:13 PDT 2015

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?



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