mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-09 12:17:12 +09:00
6665fa88b5
This patch adds the DMA_ATTR_ALLOC_SINGLE_PAGES attribute to the DMA-mapping subsystem. This attribute can be used as a hint to the DMA-mapping subsystem that it's likely not worth it to try to allocate large pages behind the scenes. Large pages are likely to make an IOMMU TLB work more efficiently but may not be worth it. See the Documentation contained in this patch for more details about this attribute and when to use it. Note that the name of the hint (DMA_ATTR_ALLOC_SINGLE_PAGES) is loosely based on the name MADV_NOHUGEPAGE. Just as there is MADV_NOHUGEPAGE vs. MADV_HUGEPAGE we could also add an "opposite" attribute to DMA_ATTR_ALLOC_SINGLE_PAGES. Without having the "opposite" attribute the lack of DMA_ATTR_ALLOC_SINGLE_PAGES means "use your best judgement about whether to use small pages or large pages". BUG=chromium:570532 TEST=Stress memory and watch cat videos. Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> (am from https://patchwork.kernel.org/patch/8007151/) Reviewed-on: https://chromium-review.googlesource.com/322334 Reviewed-by: Dmitry Torokhov <dtor@chromium.org> Change-Id: I9d0af41446b5c41d6f39a2b77e711179d0b40eca Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> Signed-off-by: Yakir Yang <ykk@rock-chips.com>