Re: [PATCH 0/3] drm: panfrost: Coherency support
From: Rob Herring <robh@kernel.org>
Date: 2020-09-16 17:48:16
Also in:
dri-devel, linux-amlogic, linux-iommu
On Wed, Sep 16, 2020 at 11:04 AM Alyssa Rosenzweig [off-list ref] wrote:
quoted
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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel