Freebsd IP Forwarding performance (question,
and some info) [7-stable, current, em, smp]
sepherosa at gmail.com
Tue Jul 1 03:34:53 UTC 2008
On 7/1/08, Paul <paul at gtcomm.net> wrote:
> I have been unable to even come close to livelocking the machine with the em
> driver interrupt moderation.
Yeah, system will not be livelocked. But even setting its imtimer to
4000, the overall system response is still worse than using polling
@4000 with a 9402PT.
> So that to me throws polling out the window. I tried 8000hz with polling
I don't believe high polling rate will improve forwarding performance.
I used to set polling rate to 2000hz, burst max to 750 and each burst
> modified to allow 10000 burst and it makes no difference
> in the amount of pps I can jam through.. It' seems to be limited by the
> routing path in the kernel more than anything else.
> If a driver/hardware didn't support interrupt mitigation then it would
> definitely lock the machine.
So polling(4) still has its place.
Live Free or Die
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