Messages in this thread |  | | | Date | Thu, 18 Jun 2009 11:13:35 -0700 | | From | Chris Wright <> | | Subject | Re: [PATCH 1/2] IOMMU Identity Mapping Support: iommu_identity_mapping definition |
* Fenghua Yu (fenghua.yu@intel.com) wrote: > IOMMU Identity Mapping Support: iommu_identity_mapping definition > > Identity mapping for IOMMU defines a single domain to 1:1 map all pci devices > to all usable memory. > > This will reduces map/unmap overhead in DMA API's and improve IOMMU performance. > On 10Gb network cards, Netperf shows no performance degradation compared to > non-IOMMU performance. > > This method may lose some of DMA remapping benefits like isolation. > > The first patch defines iommu_identity_mapping varialbe which controls the > identity mapping code and is 0 by default.
The only real difference between "pt" and "identity" is hardware support. We should have a single value we don't have to tell users to do different things depending on their hardware (they won't even know what they have) to achieve the same result.
thanks, -chris
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