Commit eb981383 authored Mar 01, 2017 by Eric Anholt

drm/vc4: Fulfill user BO creation requests from the kernel BO cache.



The from_cache flag was actually "the BO is invisible to userspace",
so we can repurpose it to just zero out a cached BO and return it to
userspace.

Improves wall time for a loop of 5 glsl-algebraic-add-add-1 by
-1.44989% +/- 0.862891% (n=28, 1 outlier removed from each that
appeared to be other system noise)

Note that there's an intel-gpu-tools test to check for the proper
zeroing behavior here, which we continue to pass.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170301185602.6873-1-eric@anholt.net

parent afc1ebf4

drivers/gpu/drm/vc4/vc4_bo.c

+7 −6

Original line number	Diff line number	Diff line
		@@ -211,20 +211,21 @@ struct drm_gem_object vc4_create_object(struct drm_device dev, size_t size)
		}

		struct vc4_bo vc4_bo_create(struct drm_device dev, size_t unaligned_size,
		bool from_cache)
		bool allow_unzeroed)
		{
		size_t size = roundup(unaligned_size, PAGE_SIZE);
		struct vc4_dev *vc4 = to_vc4_dev(dev);
		struct drm_gem_cma_object *cma_obj;
		struct vc4_bo *bo;

		if (size == 0)
		return ERR_PTR(-EINVAL);

		/* First, try to get a vc4_bo from the kernel BO cache. */
		if (from_cache) {
		struct vc4_bo *bo = vc4_bo_get_from_cache(dev, size);

		if (bo)
		bo = vc4_bo_get_from_cache(dev, size);
		if (bo) {
		if (!allow_unzeroed)
		memset(bo->base.vaddr, 0, bo->base.base.size);
		return bo;
		}