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!
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
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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