[openib-general] Re: openib-general Digest, Vol 22, Issue 114

[Shirley Ma]

Roland Dreier <rdreier at cisco.com> wrote on 04/18/2006 03:01:57 PM:

>     Shirley> After completion handler receives the notification, don't
>     Shirley> poll the CQ right away, and wait for more WIKIs in
>     Shirley> CQ. That way can reduce the CQ lock overhead.
> 
> That's interesting... it makes sense, and it argues in favor of
> deferring CQ polling to a kernel thread.  Of course this will hurt
> ping-pong latency.  Maybe it's better to just implement NAPI though...

Let's try difference implementations to see the difference.

>     Shirley> I found that there is some problem to increase the NUM_WC
>     Shirley> on recv. It hurts the performance lots. Do you have any
>     Shirley> clue?
> 
> Is this on ehca or mthca?  I couldn't explain it on mthca, but on ehca
> maybe there's a bug in generating CQ events ??
> 
>  - R.

It's on mthca. If you are interested. I can submit a test patch for your 
experimental.

Thanks
Shirley Ma
IBM Linux Technology Center
15300 SW Koll Parkway
Beaverton, OR 97006-6063
Phone(Fax): (503) 578-7638
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