[ofa-general] Coalescing interrupts in SRP

[Roland Dreier]

 > I'm not sure if the SRP stack (initiator side) polls or interrupts,
 > but I seem to be hitting a wall at ~120K transactions/second.

Interesting.  The SRP initiator is using interrupts to call
srp_completion(), which then services all pending completions and rearms
the CQ.  So it is essentially interrupt driven -- there is no polling
mechanism a la NAPI for network devices.

 > Is there any way to coalesce interrupts w/ SRP?

Not at the moment, although one could do a hack with ib_modify_cq() a la
IPoIB (assuming you're using ConnectX HCA).  A bigger piece of work
would be some sort of NAPI framework -- I think people have alreay
looked at "NAPI for blockdevices" as part of work to optimize for
high-IOPS SSDs, but I don't have pointers at the moment.

 - R.