Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 52a42cec authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/cmdparser: Accelerate copies from WC memory 



If we need to use clflush to prepare our batch for reads from memory, we
can bypass the cache instead by using non-temporal copies.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarMatthew Auld <matthew.william.auld@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-39-chris@chris-wilson.co.uk
parent 76ff480e

drivers/gpu/drm/i915/i915_cmd_parser.c

+43 −27
Original line number Diff line number Diff line
@@ -965,8 +965,7 @@ static u32 *copy_batch(struct drm_i915_gem_object *dst_obj, 
{

	unsigned int src_needs_clflush;

	unsigned int dst_needs_clflush;

	void *dst, *ptr;

	int offset, n;

	void *dst, *src;

	int ret;



	ret = i915_gem_obj_prepare_shmem_read(src_obj, &src_needs_clflush);
@@ -983,32 +982,49 @@ static u32 *copy_batch(struct drm_i915_gem_object *dst_obj, 
	if (IS_ERR(dst))

		goto unpin_dst;



	ptr = dst;

	src = ERR_PTR(-ENODEV);

	if (src_needs_clflush &&

	    i915_memcpy_from_wc((void *)(uintptr_t)batch_start_offset, 0, 0)) {

		src = i915_gem_object_pin_map(src_obj, I915_MAP_WC);

		if (!IS_ERR(src)) {

			i915_memcpy_from_wc(dst,

					    src + batch_start_offset,

					    ALIGN(batch_len, 16));

			i915_gem_object_unpin_map(src_obj);

		}

	}

	if (IS_ERR(src)) {

		void *ptr;

		int offset, n;



		offset = offset_in_page(batch_start_offset);



	/* We can avoid clflushing partial cachelines before the write if we

	 * only every write full cache-lines. Since we know that both the

	 * source and destination are in multiples of PAGE_SIZE, we can simply

	 * round up to the next cacheline. We don't care about copying too much

	 * here as we only validate up to the end of the batch.

		/* We can avoid clflushing partial cachelines before the write

		 * if we only every write full cache-lines. Since we know that

		 * both the source and destination are in multiples of

		 * PAGE_SIZE, we can simply round up to the next cacheline.

		 * We don't care about copying too much here as we only

		 * validate up to the end of the batch.

		 */

		if (dst_needs_clflush & CLFLUSH_BEFORE)

		batch_len = roundup(batch_len, boot_cpu_data.x86_clflush_size);

			batch_len = roundup(batch_len,

					    boot_cpu_data.x86_clflush_size);



		ptr = dst;

		for (n = batch_start_offset >> PAGE_SHIFT; batch_len; n++) {

			int len = min_t(int, batch_len, PAGE_SIZE - offset);

		void *vaddr;



		vaddr = kmap_atomic(i915_gem_object_get_page(src_obj, n));

			src = kmap_atomic(i915_gem_object_get_page(src_obj, n));

			if (src_needs_clflush)

			drm_clflush_virt_range(vaddr + offset, len);

		memcpy(ptr, vaddr + offset, len);

		kunmap_atomic(vaddr);

				drm_clflush_virt_range(src + offset, len);

			memcpy(ptr, src + offset, len);

			kunmap_atomic(src);



			ptr += len;

			batch_len -= len;

			offset = 0;

		}

	}



	/* dst_obj is returned with vmap pinned */

	*needs_clflush_after = dst_needs_clflush & CLFLUSH_AFTER;