[openib-general] ia64 perf and FMR

[Fab Tillier]

> From: Grant Grundler [mailto:iod00d at hp.com]
> Sent: Sunday, April 03, 2005 10:52 PM
> 
> On Fri, Apr 01, 2005 at 06:40:48PM -0800, Grant Grundler wrote:
> > I've a vague idea what "Fast Memory Registration" is but not a good
> > understanding.  Can someone point me at a decent explanation of FMR?
> 
> I'm still fishing for this.
> Even tips on which docs I might scrounge through are welcome.
> 

If you have access to a Tavor PRM, you can see what they are and how they
work.  The Mellanox implementation of FMR is not the same as FMR defined in
the 1.2 IB spec.

Basically, FMR lets you register memory without using the command interface,
using memory mapped HCA resource to access the translation tables directly.
There are pitfalls with them related to the HCA caching translation entries
and cache coherency between the HCA and what the app wants it to do.

That's my current understanding, and will gladly stand corrected.  I hope
that helps some.

- Fab