[openib-general] [PATCH/RFC] IB/ipoib: add selective tx signaling

[Moni Shoua]

> Thinking about this more - why does this patch help some benchmarks?
> The amount of work it takes for the hardware to generate a completion
> is likely negligeable, and we still are scanning the same amount
> of TX WRs in a loop to unmap/free them.
This makes sense but I think you should also consider the fact that 
the tx_lock is taken once per per tx_completion so, with the patch,
the driver spends less time under lock.


> If you think about it this way, it becomes clear that your workload,
> for some reason, hits a path where you get an event very fast
> after the first completion and there is only a small number of completions
> to handle. So your patch helps just by delaying the event handler until
> there's more work to do. And I expect it wouldn't help TCP much if at all
> as there are RX WRs per each couple of TX WRs.
> 
This is a good point to check. I hope I can get to it and spend time over it next week.