drm/i915: Store i915_gem_object_is_coherent() as a bit next to cache-dirty

For ease of use (i.e. avoiding a few checks and function calls), store
the object's cache coherency next to the cache is dirty bit.

Specifically this patch aims to reduce the frequency of no-op calls to
i915_gem_object_clflush() to counter-act the increase of such calls for
GPU only objects in the previous patch.

v2: Replace cache_dirty & ~cache_coherent with cache_dirty &&
!cache_coherent as gcc generates much better code for the latter
(Tvrtko)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dongwon Kim <dongwon.kim@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Tested-by: Dongwon Kim <dongwon.kim@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170616105455.16977-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b1504a8..4ae30f7 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -52,7 +52,7 @@ static bool cpu_write_needs_clflush(struct drm_i915_gem_object *obj)
        if (obj->cache_dirty)
                return false;
 
-       if (!i915_gem_object_is_coherent(obj))
+       if (!obj->cache_coherent)
                return true;
 
        return obj->pin_display;
@@ -253,7 +253,7 @@ __i915_gem_object_release_shmem(struct drm_i915_gem_object *obj,
 
        if (needs_clflush &&
            (obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0 &&
-           !i915_gem_object_is_coherent(obj))
+           !obj->cache_coherent)
                drm_clflush_sg(pages);
 
        __start_cpu_write(obj);
@@ -856,8 +856,7 @@ int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
        if (ret)
                return ret;
 
-       if (i915_gem_object_is_coherent(obj) ||
-           !static_cpu_has(X86_FEATURE_CLFLUSH)) {
+       if (obj->cache_coherent || !static_cpu_has(X86_FEATURE_CLFLUSH)) {
                ret = i915_gem_object_set_to_cpu_domain(obj, false);
                if (ret)
                        goto err_unpin;
@@ -909,8 +908,7 @@ int i915_gem_obj_prepare_shmem_write(struct drm_i915_gem_object *obj,
        if (ret)
                return ret;
 
-       if (i915_gem_object_is_coherent(obj) ||
-           !static_cpu_has(X86_FEATURE_CLFLUSH)) {
+       if (obj->cache_coherent || !static_cpu_has(X86_FEATURE_CLFLUSH)) {
                ret = i915_gem_object_set_to_cpu_domain(obj, true);
                if (ret)
                        goto err_unpin;
@@ -3684,6 +3682,7 @@ restart:
        list_for_each_entry(vma, &obj->vma_list, obj_link)
                vma->node.color = cache_level;
        obj->cache_level = cache_level;
+       obj->cache_coherent = i915_gem_object_is_coherent(obj);
        obj->cache_dirty = true; /* Always invalidate stale cachelines */
 
        return 0;
@@ -4344,7 +4343,8 @@ i915_gem_object_create(struct drm_i915_private *dev_priv, u64 size)
        } else
                obj->cache_level = I915_CACHE_NONE;
 
-       obj->cache_dirty = !i915_gem_object_is_coherent(obj);
+       obj->cache_coherent = i915_gem_object_is_coherent(obj);
+       obj->cache_dirty = !obj->cache_coherent;
 
        trace_i915_gem_object_create(obj);
 

diff --git a/drivers/gpu/drm/i915/i915_gem_clflush.c b/drivers/gpu/drm/i915/i915_gem_clflush.c
index 17b207e..152f16c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_clflush.c
+++ b/drivers/gpu/drm/i915/i915_gem_clflush.c
@@ -139,7 +139,7 @@ void i915_gem_clflush_object(struct drm_i915_gem_object *obj,
         * snooping behaviour occurs naturally as the result of our domain
         * tracking.
         */
-       if (!(flags & I915_CLFLUSH_FORCE) && i915_gem_object_is_coherent(obj))
+       if (!(flags & I915_CLFLUSH_FORCE) && obj->cache_coherent)
                return;
 
        trace_i915_gem_object_clflush(obj);

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 2a9aed5..d6099d0 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1110,7 +1110,7 @@ eb_move_to_gpu(struct i915_execbuffer *eb)
                if (vma->exec_entry->flags & EXEC_OBJECT_ASYNC)
                        continue;
 
-               if (obj->cache_dirty)
+               if (unlikely(obj->cache_dirty && !obj->cache_coherent))
                        i915_gem_clflush_object(obj, 0);
 
                ret = i915_gem_request_await_object

diff --git a/drivers/gpu/drm/i915/i915_gem_internal.c b/drivers/gpu/drm/i915/i915_gem_internal.c
index 58e93e8..568bf83 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_internal.c
+++ b/drivers/gpu/drm/i915/i915_gem_internal.c
@@ -191,7 +191,8 @@ i915_gem_object_create_internal(struct drm_i915_private *i915,
        obj->base.read_domains = I915_GEM_DOMAIN_CPU;
        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        obj->cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
-       obj->cache_dirty = !i915_gem_object_is_coherent(obj);
+       obj->cache_coherent = i915_gem_object_is_coherent(obj);
+       obj->cache_dirty = !obj->cache_coherent;
 
        return obj;
 }

diff --git a/drivers/gpu/drm/i915/i915_gem_object.h b/drivers/gpu/drm/i915/i915_gem_object.h
index 9150578..adb482b 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/i915_gem_object.h
@@ -121,6 +121,7 @@ struct drm_i915_gem_object {
        unsigned long gt_ro:1;
        unsigned int cache_level:3;
        unsigned int cache_dirty:1;
+       unsigned int cache_coherent:1;
 
        atomic_t frontbuffer_bits;
        unsigned int frontbuffer_ggtt_origin; /* write once */

diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 681db60..a817b3e 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -590,6 +590,7 @@ _i915_gem_object_create_stolen(struct drm_i915_private *dev_priv,
        obj->stolen = stolen;
        obj->base.read_domains = I915_GEM_DOMAIN_CPU | I915_GEM_DOMAIN_GTT;
        obj->cache_level = HAS_LLC(dev_priv) ? I915_CACHE_LLC : I915_CACHE_NONE;
+       obj->cache_coherent = true; /* assumptions! more like cache_oblivious */
 
        if (i915_gem_object_pin_pages(obj))
                goto cleanup;

diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 34461e1..05c36f6 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -805,7 +805,8 @@ i915_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file
        obj->base.read_domains = I915_GEM_DOMAIN_CPU;
        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        obj->cache_level = I915_CACHE_LLC;
-       obj->cache_dirty = !i915_gem_object_is_coherent(obj);
+       obj->cache_coherent = i915_gem_object_is_coherent(obj);
+       obj->cache_dirty = !obj->cache_coherent;
 
        obj->userptr.ptr = args->user_ptr;
        obj->userptr.read_only = !!(args->flags & I915_USERPTR_READ_ONLY);

diff --git a/drivers/gpu/drm/i915/selftests/huge_gem_object.c b/drivers/gpu/drm/i915/selftests/huge_gem_object.c
index 0ca867a..caf76af 100644 (file)
--- a/drivers/gpu/drm/i915/selftests/huge_gem_object.c
+++ b/drivers/gpu/drm/i915/selftests/huge_gem_object.c
@@ -129,7 +129,8 @@ huge_gem_object(struct drm_i915_private *i915,
        obj->base.read_domains = I915_GEM_DOMAIN_CPU;
        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        obj->cache_level = HAS_LLC(i915) ? I915_CACHE_LLC : I915_CACHE_NONE;
-       obj->cache_dirty = !i915_gem_object_is_coherent(obj);
+       obj->cache_coherent = i915_gem_object_is_coherent(obj);
+       obj->cache_dirty = !obj->cache_coherent;
        obj->scratch = phys_size;
 
        return obj;