Re: Q: cpuidle results in degredation in ethernet performance ?

[Daniel Lezcano <daniel.lezcano@linaro.org>]

On 08/01/2015 09:34 PM, Ran Shalit wrote:
> Hello,
>
> Maybe if someone here understands cpuidel he can help me...
>
> I am using omap, with cpuidel and I have some strange behaviour only
> when cpuidle is used:
> 1.  I test ethernet bandwidth with iperf
> 2. With large packet test (16k), I get same bandwidth in version with
> cpuidle support as in version without cpuidel supported.
> 3. With small packet test (<2000 bytes), I get high degredation in
> performance in version with cpuidle. On viewing statistics I see that
> the cpu gets into cpu inactive state (C3 state -  not retention yet,
> only cpu not active). I guess this is the cuase of the degredation.
> With large packets I get no increment in C3 state usage.
> 4. I think that menu governer behaviour might explain this, but I
> don't understand it deeply enough.
>
> Can anyone shed a light on this ? Is there anything I can do to overcome this ?

Is an omap3 or omap4 ?



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