On Mon, May 07, 2018 at 12:19:01AM +0300, Dmitry Osipenko wrote:
> Probably the best variant would be to give an explicit control over syncing
> to a
> user of the IOMMU API, like for example device driver may perform multiple
> mappings / unmappings and then sync/flush in the end. I'm not sure that it's
> really worth the hassle to shuffle the API right now, maybe we can implement
> it
> later if needed. Joerg, do you have objections to a 'compound page' approach?
Have you measured the performance difference on both variants? The
compound-page approach only works for cases when the physical memory you
map contiguous and correctly aligned.
If it is really needed I would prefer a separate iotlb_sync_map()
call-back that is just NULL when not needed. This way all users that
don't need it only get a minimal penalty in the mapping path and you
don't have any requirements on the physical memory you map to get good
performance.
Joerg
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
