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

[Muli Ben-Yehuda]

On Fri, Jun 27, 2008 at 07:40:35PM +0200, Joerg Roedel wrote:

> Yes. As I said, this is for the non-isolating case. For the
> isolation case (which is needed for protection) it is harder to
> optimize. But there I think about some sort of lazy IOMMU TLB
> flushing. The flushing and 'wait for the flush to finish' is the
> most expensive part in the mapping and unmapping code path. But this
> needs some experiments.

Agreed. The paper I just posted to the iommu mailing list has some
ideas and experimental data.

> > I am thinking of them and I'd be surprised if you'd find any in
> > such machines. Certainly I assume none of the on-board devices
> > will have this ancient limitation. But hey, it could happen ;-)
> 
> The IOMMU machine under my desk has a 32bit PCI slot with a card in
> it :-)

Touche :-)

Cheers,
Muli
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