Re: NO_HZ migration of TCP ack timers

[Andi Kleen]

On Thu, Feb 18, 2010 at 08:55:30PM +1100, Anton Blanchard wrote:
> 
> Hi Andi,
> 
> > If the nohz balancer CPU is otherwise idle, shouldn't it have enough
> > cycles to handle acks for everyone? Is the problem the cache line
> > transfer time?
> 
> Yeah, I think the timer spinlock on the nohz balancer cpu ends up being a
> global lock for every other cpu trying to migrate their ack timers to it.

And they do that often for short idle periods?

For longer idle periods that should be not too bad.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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