[openib-general] IPOIB NAPI

[Michael S. Tsirkin]

> Quoting Shirley Ma <xma at us.ibm.com>:
> Subject: Re: [openib-general] IPOIB NAPI
> 
> Roland Dreier <rdreier at cisco.com> wrote on 02/27/2007 02:41:44 PM:
> 
> >  > So the IBV_CQ_REPORT_MISSED_EVENTS has been part of OFED-1.2 already? I can
> >  > generate the patch for all ULPs to use this for review. Do you need me to
> >  > do that?
> > 
> > No, it's not in OFED 1.2 or the upstream kernel.  And no one has
> > implemented it for userspace (and I'm somewhat reluctant to break the
> > ABI at this point without some performance numbers to motivate making
> > this API change).
> > 
> > Have the NAPI performance problems with ehca been resolved?  We could
> > probably merge IPoIB NAPI for 2.6.22 then, which would pull in the
> > kernel changes at least.
> > 
> >  - R.
> We have addressed the NAPI performance issues with ehca driver. I believe the patches have been upper stream. However the test results show that it's better to delay poll again to next NAPI interval, something like this:
> 
> poll-cq
> notify-cq, if missed_event && netif_rx_reschedule()
> return 1
> 
> vs.
> poll-cq,
> notify-cq, if missed_event && netif_rx_reschedule()
> poll again
> return 0
> 
> It seems ehca delivering packet much faster than other HCAs. So poll again would stay in the loop for many many times. So the above changes doesn't impact other HCAs, I would recommand it. I saw same implementations on other ethernet drivers.

I'm confused. Which one is faster?

-- 
MST