On Fri, Nov 20, 2015 at 10:55:58AM +0000, Chris Wilson wrote:
> Since we blow the TLB caches by using kmap/kunmap, we may as well go the
> whole hog and see if declaring our destination page as WC is faster than
> keeping it as WB and using clflush. It should be!
Is this description for another patch? I can't see any WC stuff in
there.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_cmd_parser.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
> index c6f6d9f2b2ce..4a3e90b042c5 100644
> --- a/drivers/gpu/drm/i915/i915_cmd_parser.c
> +++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
> @@ -992,9 +992,10 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
> const struct drm_i915_cmd_descriptor *desc = &default_desc;
> u32 last_cmd_header = 0;
> unsigned dst_iter, src_iter;
> - int needs_clflush = 0;
> struct get_page rewind;
> void *src, *dst, *tmp;
> + int src_needs_clflush = 0;
> + bool dst_needs_clflush;
> u32 partial, length = 1;
> unsigned in, out;
> bool oacontrol_set = false; /* OACONTROL tracking. See check_cmd() */
> @@ -1007,13 +1008,19 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
> if (WARN_ON(shadow_batch_obj->pages_pin_count == 0))
> return -ENODEV;
>
> - ret = i915_gem_obj_prepare_shmem_read(batch_obj, &needs_clflush);
> + ret = i915_gem_obj_prepare_shmem_read(batch_obj, &src_needs_clflush);
> if (ret) {
> DRM_DEBUG_DRIVER("CMD: failed to prepare shadow batch\n");
> return ret;
> }
>
> - ret = i915_gem_object_set_to_cpu_domain(shadow_batch_obj, true);
> + dst_needs_clflush =
> + shadow_batch_obj->base.write_domain != I915_GEM_DOMAIN_CPU &&
> + !INTEL_INFO(shadow_batch_obj->base.dev)->has_llc;
> + if (dst_needs_clflush)
> + ret = i915_gem_object_set_to_gtt_domain(shadow_batch_obj, true);
> + else
> + ret = i915_gem_object_set_to_cpu_domain(shadow_batch_obj, true);
> if (ret) {
> DRM_DEBUG_DRIVER("CMD: Failed to set shadow batch to CPU\n");
> goto unpin;
> @@ -1048,7 +1055,7 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
> this = PAGE_SIZE - in;
>
> src = kmap_atomic(i915_gem_object_get_page(batch_obj, src_iter));
> - if (needs_clflush)
> + if (src_needs_clflush)
> drm_clflush_virt_range(src + in, this);
>
> if (this == PAGE_SIZE && partial == 0)
> @@ -1151,6 +1158,8 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
> int len;
>
> if (out == PAGE_SIZE) {
> + if (dst_needs_clflush)
> + drm_clflush_virt_range(dst, PAGE_SIZE);
> kunmap_atomic(dst);
> dst = kmap_atomic(i915_gem_object_get_page(shadow_batch_obj, ++dst_iter));
> out = 0;
> @@ -1179,6 +1188,8 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
> kunmap_atomic(src);
> in = 0;
> }
> + if (dst_needs_clflush)
> + drm_clflush_virt_range(dst, out);
> unmap:
> kunmap_atomic(src);
> kunmap_atomic(dst);
> --
> 2.6.2
>
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--
Ville Syrjälä
Intel OTC
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