On Wed, Mar 13 2024 at 23:33, Boqun Feng wrote:
> but here:
>
> [ 221.555265] kworker/-44 0d.... 3279414us : timer_start:
> timer=95703ccd function=process_timeout expires=4294670586 [timeout=10]
> bucket_expiry=4294670587 cpu=0 idx =59 flags=
>
> this is a normal timer.
>
> [ 221.571298] rcu_sche-15 3d.... 3279417us : timer_start:
> timer=7e541f87 function=process_timeout expires=4294670579 [timeout=3]
> bucket_expiry=4294670580 cpu=3 idx= 52 flags=
> [ 221.587241] <idle>-0 1d.s.. 3283405us : timer_cancel:
> timer=7e541f87
> [ 221.594488] <idle>-0 1..s.. 3283407us :
> timer_expire_entry: timer=7e541f87 function=process_timeout now=4294670580
> baseclk=4294670580
> [ 221.607388] rcu_sche-15 3d.... 3283416us : timer_start:
> timer=7e541f87 function=process_timeout expires=4294670583 [timeout=3]
> bucket_expiry=4294670584 cpu=3 idx= 56 flags=
> [ 221.623331] <idle>-0 1d.s.. 3287404us : timer_cancel:
> timer=7e541f87
> [ 221.630578] <idle>-0 1..s.. 3287405us :
> timer_expire_entry: timer=7e541f87 function=process_timeout now=4294670584
> baseclk=4294670584
> [ 221.643475] <idle>-0 0d.s.. 162361292us : timer_cancel:
> timer=95703ccd
> [ 221.650896] <idle>-0 0..s.. 162361292us :
> timer_expire_entry: timer=95703ccd function=process_timeout now=4294829657
> baseclk=4294670587
>
> which got fired here.
>
> [ 221.663967] <idle>-0 0dns.. 162361296us : timer_cancel:
> timer=d03eaa1d
> [ 221.671388] <idle>-0 0.ns.. 162361297us :
> timer_expire_entry: timer=d03eaa1d function=process_timeout now=4294829657
> baseclk=4294670856
>
> And looks to me CPU 0 is the tick_do_timer_cpu CPU, since it's the first
> one that got timers after a long wait and was doing a few catch-ups. Now
> the problem is why CPU 0 didn't program its hardware timer to expire at
> 4294670587? I.e. the earliest timer.
That's not the problem. It's not clear whether CPU0 was the last one
going idle. It doesn't look so:
> [ 221.623331] <idle>-0 1d.s.. 3287404us : timer_cancel:
> timer=7e541f87
> [ 221.630578] <idle>-0 1..s.. 3287405us :
> timer_expire_entry: timer=7e541f87 function=process_timeout now=4294670584
> baseclk=4294670584
The timer in question is supposed to wake up 2 ticks later, so CPU1
should have armed it. But without the migration trace points enabled
this is all guess work.
Thanks,
tglx
