[openib-general] Re: MMIO reads for IPoIB w/MSI-X

[Michael S. Tsirkin]

Quoting r. Grant Grundler <iod00d at hp.com>:
> Subject: Re: MMIO reads for IPoIB w/MSI-X
> 
> On Sun, Jan 23, 2005 at 12:00:17AM +0200, Michael S. Tsirkin wrote:
> > Quoting r. Grant Grundler <iod00d at hp.com>:
> > > Subject: MMIO reads for IPoIB w/MSI-X
> > > 
> > > Hi all,
> > > In trying to understand why netperf TCP_STREAM sucks on the ia64 platform
> > > I'm slowly collecting more data. I didn't really have any time this
> > > week to poke at this issue.
> > > 
> > > The follow data confirms in MSI-X mode mthca is essentially doing
> > > no MMIO reads.
> > 
> > An additional advantage of MSI-X is that interrupts are not shared.
> > But how is this related to ia64?
> 
> How is _what_ related to ia64?
> 
> MMIO reads hurt perf. MSI-X shouldn't need any MMIO reads and
> I confirmed that is fact the case as a first step to understanding
> why ia64-linux perf is "suboptimal".
> 
> grant

I understand.
But, do they hurt perf on ia64 more than on x86?

-- 
I dont speak for Mellanox.