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SubjectRE: [PATCH] lan78xx: Protect runtime_auto check by #ifdef CONFIG_PM
On Mon, 21 Mar 2016 Woojung.Huh@microchip.com wrote:

> > But this leaves open the issue that querying the device too often will
> > prevent it from going into autosuspend. It seems to me that the best
> > way to deal with this is to make sure that the autosuspend timeout is
> > shorter than the interal between queries, not to make the querying
> > conditional on !runtime_auto.
>
> Short autosuspend timeout can affect performance. For instance our experiments showed that
> shorter than 10sec timeout made Ethernet performance degrade because of wakeup delays.
> So, just putting shorter timeout may have some side effects.

Sure. This just means that you need a long statistics interval --
longer than the autosuspend timeout. That's why I suggested making the
interval adjustable.

Alternatively, you could automatically set the statistics interval to
the autosuspend timeout (or 0 if autosuspend is disabled) plus some
fixed value.

Alan Stern

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