From: Steven Rostedt
Date: Tue May 20 2008 - 09:54:20 EST


It seems that you may be new to the lists, so I will let you know,
please do not top post. It is appropriate to either bottom post or
better yet, inline reply. See

On Tue, 20 May 2008, MA QING A wrote:

> Thanks very much for your explanation
> At the very beginning I thought the Hackbench was a latency tools, so
> I was very surprised to see such result.
> But there's another question. When I choose the Complete Preemption
> -Real Time configuration, it's recommended to choose Timer Frequency
> ---> 1000Mhz to improve the cpu performance, does it mean cpu will cost
> much more during the thread context switch? Or I should choose 100Mhz in
> order to decrease the thread context switch and get a better
> performance?
> Which one should I choose? Or any useful tools can tell me the differences.

I'm not sure where you read that. With the introduction of high-resolution
timers, the HZ value isn't that important anymore. Things that might use
select or poll as timeouts will still be at the HZ frequency, but other
code that uses proper timer API will still react well.

Matters what you are doing. Try out different values yourself and see what
you find is the best. You can also report your findings if you want.


-- Steve

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