[openib-general] basic IB doubt

[Greg Lindahl]

On Thu, Aug 24, 2006 at 03:37:21PM -0700, Sean Hefty wrote:

> I'm missing the standard you're using to judge what's theoretically good and
> bad.

Having simpler programming to get good performance is a theoretical
good. Extra hacks for specific hardware is theoretically bad,
pratically good only when it ends up with much better performance.

Silently non-standard software is bad by both accounts.

> Applications are written this way today.  A vendor can either:
> 
> * Support those apps by providing the feature.
> * Require that the apps be rewritten to use their hardware.

That's what I was calling practical. It's clear what a hardware
vendor will do in that case.

> Whether apps should have been written this way seems irrelevant.  They are, and
> we should make decisions based on that, including extending the spec and/or
> implementation if needed.

In this case we're talking about code which can easily be changed to
follow the standard, in addition to having a hack mode that's faster
on 1 particular hardware implementation.

You seem to be implying that the applications are set in stone, and
that their authors have no interest in making them
standard-conformant. I don't think that's the case. If there is a
standard extension which can provide better performance on 1 particular
hardware implementation, let's add it to the standard. But let's
also make the software standard-conformant on other hardware.

-- greg