16 Sep
2020
16 Sep
'20
5:46 p.m.
On Wed, Sep 16, 2020 at 11:04 AM Alyssa Rosenzweig alyssa.rosenzweig@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