Re: too many timer retries happen when do local timer swtich with broadcast timer

Lorenzo Pieralisi
2013-02-22T10:31:53Z

On Fri, Feb 22, 2013 at 10:24:00AM +0000, Thomas Gleixner wrote:
> On Fri, 22 Feb 2013, Santosh Shilimkar wrote:
> > BTW, Lorenzo off-list mentioned to me about warning in boot-up
> > which I missed while testing your patch. It will take bit more
> > time for me to look into it and hence thought of reporting it.
> >
> > [ 2.186126] ------------[ cut here ]------------
> > [ 2.190979] WARNING: at kernel/time/tick-broadcast.c:501
> > tick_broadcast_oneshot_control+0x1c0/0x21c()
>
> Which one is that? tick_broadcast_pending or tick_force_broadcast_mask ?

It is the tick_force_broadcast_mask and I think that's because on all
systems we are testing, the broadcast timer IRQ is a thundering herd,
all CPUs get out of idle at once and try to get out of broadcast mode
at more or less the same time.

Lorenzo