[openib-general] Help with CONFIG_PCI_MSI in the kernel

[Grant Grundler]

On Mon, Apr 03, 2006 at 03:14:56PM -0700, Greg Lindahl wrote:
> Red Hat has started turning off CONFIG_PCI_MSI in their kernels (FC5
> and the latest FC4 update). I remember a while back there was a
> discussion about how MSI made the Mellanox HCA run faster, can someone
> please add some concrete details about this to the bug? Thanks.

Greg,
The only evidence I have is one AMD chipset is buggy WRT MSI.
And this was already noted in the bug report.

I also don't see why MSI support should be disabled.
MSI should work fine on most of the platforms out there.
For the cases where MSI does not work correctly and there
is no workaround in place yet, Matthew Wilcox proposed a
"platform" MSI disable patch. User can then disable
MSI globally at boot time.

Besides Infiniband, newer Broadcom gige chips, LSI MPT cards,
and most 10gige cards support MSI/MSI-X. I'm sure there are
alot more devices than that though. So yes, optimal system performance
will want MSI working.

hth,
grant

> 
> http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=186520
> 
> -- greg
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