On Wed, Sep 16, 2020 at 11:04 AM Alyssa Rosenzweig <alyssa.rosenzw...@collabora.com> wrote: > > > So I get a performance regression with the dma-coherent approach, even if > > it's > > clearly the cleaner. > > That's bizarre -- this should really be the faster of the two.
Coherency may not be free. CortexA9 had something like 4x slower memcpy if SMP was enabled as an example. I don't know if there's anything going on like that specifically here. If there's never any CPU accesses mixed in with kmscube, then there would be no benefit to coherency. Rob _______________________________________________ iommu mailing list firstname.lastname@example.org https://lists.linuxfoundation.org/mailman/listinfo/iommu