[ofa-general] Re: [PATCH 0/5]: Improve small UDP messages

[Shirley Ma]

Hello Eli,

	I am going to verify this in our lab. I assume this patchset is built
against 2.6.25?

On Fri, 2008-02-01 at 15:40 +0200, Eli Cohen wrote:
> The following patches, based on ofed 1.3, are intended to address bugs
> https://bugs.openfabrics.org/show_bug.cgi?id=760 and
> https://bugs.openfabrics.org/show_bug.cgi?id=761. They address UD mode
> both send and receive and improve performance when using small
> messages
> UDP traffic. The observation we had is that at small UDP messages, the
> message rate is high and so what limits throughput is CPU, e.g. CPU is
> 100% busy.
What's the configuration for this test? How many CPUs?

> In the send flow I use a dedicated CQ for the send flow which in turn
> is
> never armed. CQEs consumption is done by polling after posting a send
> message. Also, the QP is configured for selective signaling and
> polling
> the CQ is done once in 16 messages.

I did see selective signaling impact the performance. Depends on how
many packets you want to pull once, the performance could be good, could
be worse from my experience based on how many you want to pull once. I
haven't fully understood this yet. I have a similar patch. But why you
pick up 16 messages? 

> On the receive side the code is changed to post to receive queue once
> in
> 16 completions. This is done in for both UD and and CM.

Ohmm, have you tested latency? I think it will increase latency for
small messages.

Thanks
Shirley