Friday, July 27, 2007

nxge and IP forwarding

You may or may not be aware of project Sitara. One of the goals of project Sitara is to fix the handling of small packets.

I have achieved a milestone... using a hacked version of the nxge driver (diffs available on request), I've been able to get UDP forwarding rates as high as 1.3M packets per sec (unidirectional) across a single pair of nxge ports, using Sun's next sun4v processor. (That's number of packets forwarded...) This is very close to line rate for a 1G line. I'm hoping that future enhancements will get us to significantly more than that... maybe as much as 2-3 Mpps per port. Taken as an aggregate, I expect this class of hardware to be able to forward up to 8Mpps. (Some Sun internal numbers using a microkernel are much higher than that... but then you'd lose all the nice features that the Solaris TCP/IP stack has.)

By the way, its likely that these results are directly applicable to applications like Asterisk (VoIP), where small UDP packets are heavily used. Hopefully we'll have a putback of the necessary tweaks before too long.

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