Re: [PATCH 01/34] AMD IOMMU: add Kconfig entry

[Joerg Roedel]

On Fri, Jun 27, 2008 at 08:54:59PM +0200, Andi Kleen wrote:
> Joerg Roedel <joro@xxxxxxxxxx> writes:
> 
> > On Fri, Jun 27, 2008 at 12:39:45PM -0400, Muli Ben-Yehuda wrote:
> >> On Fri, Jun 27, 2008 at 04:47:29PM +0200, Andi Kleen wrote:
> >> 
> >> > Also it should ideally describe that there is a trade off between
> >> > reliability and performance with IOMMU enabled.
> >> 
> >> I agree that there's a performance tradeoff with current generation
> >> hardware and ingerfaces, but it wouldn't be fair to single out a
> >> single IOMMU implementation ;=)
> >
> > True. At least for the case without device isolation I have some
> > optimizations in mind which will minimize the performance tradeoff. I
> > hope to have them ready for 2.6.28 :)
> 
> Not sure that would be very useful. Outside of virtualization device
> isolation is the main feature of an IOMMU on a native kernel.

I agree that device isolation is one of the a main usage scenarios for
an IOMMU. But if somebody want to use it for virtualization and doesn't
need device isolation this optimization would be usefull.

Joerg

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