[openib-general] [PATCH] IB/ipoib: NAPI

[Christoph Raisch]

> Roland,
>
> > Do you know how ehca behaves?  Does it have that race?  ie what
> > happens in this situation:
> >
> >     poll CQ -> CQ is empty
> >         (new completion is added to CQ)
> >     request notify on CQ
> >         (no more completions are added)
> >
> > Mellanox HCAs will generate a CQ event in this case, although it's not
> > strictly required by the IB spec.  How will ehca behave?
> >
> >  - R.
>
> That could be the reason. I did see mthca poll empty entry, but not
> on ehca. I will confirm this with ehca team.
>
> Thanks
> Shirley Ma

It's possible that a race will happen between the interrupt handler, the
poll routine and the hardware.
By doing a

     poll CQ -> CQ is empty
         (new completion is added to CQ)
     request notify on CQ
         (no more completions are added)
     poll one more time

you should be on the safe side.

Gruss / Regards . . . Christoph Raisch