[openib-general] Performance Degradation with OFED v. Voltaire

[Michael S. Tsirkin]

> > Hi,
> > 
> > We'd dearly like some help to understand why we seem to be having
> > performance issues with OFED.  When we run a lustre network bandwidth
> > benchmark, we find significant performance degradation on OFED versus
> > Voltaire...
> > 
> >              Premap (256 RDMA frags)     Map on demand (1 RDMA frag)
> >              Voltaire  OFED  Ratio       Voltaire  OFED  Ratio 
> > Writes MB/s  682       567   83 %        577       436   75 %
> > Reads MB/s   658       554   84 %        555       432   77 %
> 
>   Where these tests run on the same hardware setup?  If so was it PCI-X
> or PCIe?  HCA firmware version would also be useful.

Good point, Matt, thanks!
This gives me an idea: try loading mthca with tune_pci=1.
If this helps, this is a BIOS issue.

-- 
MST