On Wed, Mar 01, 2017 at 04:09:38PM -0500, Konrad Rzeszutek Wilk wrote: > .snip.. > > > > No. SVM is purely about sharing CPU address space with device. Command > > submission is still through kernel driver which controls rings (with SVM then > > you can put VA into those commands). There are other vendor specific > > features to enable direct user space submission which is orthogonal to SVM. > > Apologies for my ignorance but how is this beneficial? As in > currently you would put in bus addresses on the ring, but now you > can put VA addresses. > > The obvious benefit I see is that you omit the DMA ops which means there is > less of 'lookup' (VA->bus address) in software - but I would have thought this > would be negligible performance impact? And now the IOMMU alongside with > the CPU would do this lookup. > > Or are there some other improvements in this? Other benefits include, - Application can simply pass its pointers to the SVM capable devices. which means no memory registration overhead to get IO Virtual Addresses. - No need to pin memory for DMA, since the devices can handle faults and can request pages to be paged-in on demand. > > > > > Thanks > > Kevin > _______________________________________________ > iommu mailing list > iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linuxfoundation.org/mailman/listinfo/iommu
