There will be a bridge chip, and indeed I see better performance when I just
use a 2-port Intel NIC as opposed to a 4 port, even if I am only actively
using 2 of the 4 ports on the 4-port NIC. For the tg3 hardware I only have a
4-port NIC. I do assume that a 2-port tg3 NIC w/out a bridge chip would be
faster..but probably not too much.
I have been taught by several wise old engineers that the proper spelling of
assume is ass-u-me :)
Bridge chips can in theory do all sorts of nasty things to performance.
CKO == IP checksum offload?
Yes.
Since Dave doesn't want to debug my bridge setup (and I don't blame him), I
am going to try to focus my testing/debug reports on the pktgen tests.
If/when pktgen shows better performance with tg3, I can verify that I see the
same speedups with my proprietary bridging module. I've no idea if CKO would
help or hinder pktgen, nor have I tried to enable or disable it.
Are your interface interrupts distributed across the CPUs?
I'm using FC2, basically a default install. It does seem to have an irq
balance daemon running. But, I'm not specifically binding IRQs or anything
like that. pktgen tx is running as a single thread, so the rx code could run
mostly on the other CPU if locking allows...
again, never ass-u-me.
rick
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