[openib-general] Re: IBM utilizing and testing openIB release 1 RCx

[Roland Dreier]

    Shirley> Michael, Different workloads could use different
    Shirley> send/recv queue sizes, also different HCAs could pick up
    Shirley> different send/recv queue sizes to utilize the HCA
    Shirley> performance. These parameters should be tunable instead
    Shirley> of setting default values in IPoIB. Also Kevin pointed
    Shirley> out, we don't want to waste the kernel memory when not
    Shirley> necessary.

Hmm, it seems having a big send queue would be pretty cheap.  Maybe we
should just increase the TX queue to something like 256 and be done
with it -- would you ever want a huge work queue?  It seems that
setting the network stack's txqueuelen should be sufficient beyond
that length.

RX is a little trickier, because the receive buffers consume quite a
bit of memory.  Maybe we should just create a big receive work queue
but not fill it by default?  That would allow the RX queue to be
increased/decreased dynamically while the device is running.

By leaving the work queue sizes compile-time constants, we make the
code a tiny fraction more efficient.

 - R.