Re: RFC: issues concerning the next NAPI interface

Linas Vepstas
2007-08-24T21:35:30Z

On Fri, Aug 24, 2007 at 11:11:56PM +0200, Jan-Bernd Themann wrote:
> (when they are available for
> POWER in our case).

hrtimer worked fine on the powerpc cell arch last summer.
I assume they work on p5 and p6 too, no ??

> I tried to implement something with "normal" timers, but the result
> was everything but great. The timers seem to be far too slow.
> I'm not sure if it helps to increase it from 1000HZ to 2500HZ
> or more.

Heh. Do the math. Even on 1gigabit cards, that's not enough:

(1gigabit/sec) x (byte/8 bits) x (packet/1500bytes) x (sec/1000 jiffy)

is 83 packets a jiffy (for big packets, even more for small packets,
and more again for 10 gigabit cards). So polling once per jiffy is a
latency disaster.

--linas