[openib-general] Help with CONFIG_PCI_MSI in the kernel

[Grant Grundler]

On Tue, Apr 04, 2006 at 01:36:54AM -0700, Greg Lindahl wrote:
> On Mon, Apr 03, 2006 at 09:36:00PM -0700, Grant Grundler wrote:
> 
> > The only evidence I have is one AMD chipset is buggy WRT MSI.
> 
> Grant,
> 
> I know about that case, the kernel disables stuff if it sees an AMD
> 8131 due to a bug. What I am referring to was IPoIB performance on
> Mellanox HCAs being improved with MSI. I figure if it's gotten this
> far with Red Hat turning it off, concrete examples are in order.

I understood and I'm trying to provide an argument for turning
MSI support back ON.

I'm very aware of the impact that MSI has on performance:

http://iou.parisc-linux.org/ols_2002/porting_zx1.pdf
http://iou.parisc-linux.org/ols_2004/pfmon_for_iodorks.pdf

Search for "MSI" in either pdf.
I might have some of the minor details wrong in either paper.
Please send corrections to me privately only if there are gross
errors of fact.

thanks,
grant