What do people think about adaptive polling?

Hasso Tepper hasso at estpak.ee
Tue Dec 12 00:22:37 PST 2006

Matthew Dillon wrote:
> :This would be very useful for things like network cards which
> :could switch from interrupt to polling mode on the fly and get
> :better performance with higher load.
>     It's hard to how many is too many, but this would certainly be a
>     benefit to older network cards which do not have interrupt moderation.

Linux network developers have made statements that best results can be
achieved always if both - interrupt moderation and adaptive polling (ie.
NAPI in Linux) are used. I don't have any pointers to test results though. 

Note that NAPI isn't just adaptive polling algorithm, but also splitting
interrupt work into to parts (hardware interrupt handler and softirq). This
might be big contributor to the win from using both in the same time as

Hasso Tepper

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