[openib-general] [PATCH/RFC 1/2] IB: Return "maybe_missed_event" hint from ib_req_notify_cq()

[Michael S. Tsirkin]

Quoting r. Shirley Ma <xma at us.ibm.com>:
> Subject: Re: [PATCH/RFC 1/2] IB: Return "maybe_missed_event" hint from ib_req_notify_cq()
> 
> "Michael S. Tsirkin" <mst at mellanox.co.il> wrote on 10/19/2006 01:21:45 PM:
> 
> > Please also note that due to factors such as TCP window limits, TX on a single
> > socket is often stalled.  To really stress a connection and see benefit from
> > NAPI you should be running multiple socket streams in parallel:
> > either just run multiple instances of netperf/netserver, or use iperf with -P flag.
> 
> I used to get 7600Mb/s IPoIB one socket duplex throughput with my other IPoIB patches on 2.6.5 kernel under certain configuration. Which makes me believe we could gain close to link throughput with one UD QP. Now I couldn't get it anymore on the new kernel. I was struggling with TCP window limits on the new kernel. Do you have any hint?

Could be the stretch ACK fix - newer kernels are sending much more ACKs
than 2.6.5. Without NAPI, this means we have more interrupts -> lower
throughput.

-- 
MST