Re: NO_HZ migration of TCP ack timers

[Andi Kleen <andi@firstfloor.org>]

> > > What should we do? Should we use mod_timer_pinned here? Or is this an issue
> > 
> > Sounds like something that should be controlled by the cpufreq governour's
> > idle predictor? Only migrate if predicted idle time is long enough.
> > It's essentially the same problem as deciding how deeply idle to put
> > a CPU. Heavy measures only pay off if the expected time is long enough.
> > 
> 
> cpuidle infrastructure hs statistics about the idle times for
> all the cpus. Maybe we can look to use this infrastructure to decide
> whether to migrate timers or not?

Yes sorry I reallhy meant cpuidle when I wrote cpufreq. 
That's what I suggested too.

But if the problem is lock contention on the target CPU that would
still not completely solve it, just make it less frequent depending
on the idle pattern.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.