Eric> Does mthca support NAPI? If you are interrupt limited I
Eric> suspect that will help. With the MSI-X comments it sounds
Eric> like you are interrupt limited.
NAPI doesn't have any relevance to mthca -- it needs to be implemented
in the IPoIB driver.
I actually tried adding NAPI to the IPoIB driver a while ago and it
didn't help at all. I'm not sure that the interrupt rate is the
limit-- IPoIB seems to be CPU-bound.
Eric> Last time I was messing around I could get 600MB/s with UD
Eric> packets so it looks like there is still room from IBoIP to
Eric> go. And that has been achieved with the Linux IP stack with
Eric> 10 GigE adapters. What part checksum offloading and tuning
Eric> for IP workloads in the hardware design I don't know. Still
Eric> when memory bandwidth is greater than 3x the network speed I
Eric> expect it mostly because a question of how much of your cpu
Eric> the communication will utilize.
I know 10 gigE has shown some very high numbers, but I assume that's
doing sendfile() with 9K jumbo frames. Do you know how well they do
in non-zero-copy workloads with a 2K MTU?
- R.
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