media: staging: media: tegra-vde: Defer dmabuf's unmapping
Frequent IOMMU remappings take about 50% of CPU usage because there is quite a lot to remap. Defer dmabuf's unmapping by 5 seconds in order to mitigate the mapping overhead which goes away completely and driver works as fast as in a case of a disabled IOMMU. The case of a disabled IOMMU should also benefit a tad from the caching since CPU cache maintenance that happens on dmabuf's attaching takes some resources. Signed-off-by: NDmitry Osipenko <digetx@gmail.com> Signed-off-by: NHans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>
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