Re: High scheduler wake up times

[Arjan van de Ven]

On Sat, 30 Jan 2010 21:47:18 -0600
Shawn Bohrer <shawn.bohrer@xxxxxxxxx> wrote:
> 
> Of course that patch makes my situation worse, which was my point.  We
> are depending on the _current_ epoll_wait() implementation which calls
> schedule_timeout(1).  

> You do agree that the current epoll_wait()
> implementation sleeps less than 1 msec with HZ == 1000 correct? 

I agree with your hypothesis, but I wouldn't call the behavior
correct ;-)

First of all, jiffies based timeouts are supposed to round *up*, not
down, and second.. it should really be just 1 msec.


> With the old kernel I can run 500 of these processes, and I'm hoping
> that I'm simply missing the knob I need to tweak to achieve similar
> performance on a recent kernel.

can you run powertop during your workload? maybe you're getting hit by
some C state exit latencies tilting the rounding over the top just too
many times...


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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