Re: too many timer retries happen when do local timer swtich withbroadcast timer

From: Lorenzo Pieralisi
Date: Fri Feb 22 2013 - 05:31:56 EST

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.


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