[openib-general] [PATCH] mthca: eq doorbell coalescing + prevent even queque overrun

[Or Gerlitz]

Michael >>> I am seeing EQ overruns in SDP stress tests: if CQ completion
Michael >>> handler arms a CQ, this could generate more EQEs,

Or >> I see that the mad, ipoib and srp CQ handlers work as follows: 
first -
Or >> arm the CQ, second - poll the CQ in a loop till it is emtpy.
Or >> does it means that completions occurring while the handler is 
running cause
Or >> interrupts which could be saved?

Michael > Handlers are running out of the interrupt context, so
Michael > an interrupt would have to be generated in the window while
Michael > CQ is being armed. Profiling I've done on ipoib shows that
Michael > this is quite unlikely.

Sorry, i dont follow. If you arm the CQ when there is one WC in it and 
then start polling, and during your polling a "second" WC is generated 
by the HCA, wouldn't an interrupt related to the 2nd completion be 
generated - why the case you are mentioning is the arming window?