This speeds up pwrite and pread from ~120 µs ro ~100 µs for reading/writing 1mb on my snb (if the backing storage pages are already pinned, of course).
v2: Chris Wilson pointed out a claring page reference bug - I've unconditionally dropped the reference. With that fixed (and the associated reduction of dirt in dmesg) it's now even a notch faster.
Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch --- drivers/gpu/drm/i915/i915_gem.c | 42 +++++++++++++++++++++++++++++--------- 1 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 8fd175c..5b8a7c5 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -339,6 +339,7 @@ i915_gem_shmem_pread(struct drm_device *dev, int obj_do_bit17_swizzling, page_do_bit17_swizzling; int hit_slowpath = 0; int needs_clflush = 0; + int release_page;
user_data = (char __user *) (uintptr_t) args->data_ptr; remain = args->size; @@ -373,10 +374,16 @@ i915_gem_shmem_pread(struct drm_device *dev, if ((shmem_page_offset + page_length) > PAGE_SIZE) page_length = PAGE_SIZE - shmem_page_offset;
- page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); - if (IS_ERR(page)) { - ret = PTR_ERR(page); - goto out; + if (obj->pages) { + page = obj->pages[offset >> PAGE_SHIFT]; + release_page = 0; + } else { + page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); + if (IS_ERR(page)) { + ret = PTR_ERR(page); + goto out; + } + release_page = 1; }
page_do_bit17_swizzling = (page_to_phys(page) & (1 << 17)) == 0; @@ -395,6 +402,9 @@ i915_gem_shmem_pread(struct drm_device *dev, }
hit_slowpath = 1; + if (!release_page) + page_cache_get(page); + release_page = 1;
mutex_unlock(&dev->struct_mutex);
@@ -416,7 +426,8 @@ i915_gem_shmem_pread(struct drm_device *dev, mutex_lock(&dev->struct_mutex); next_page: mark_page_accessed(page); - page_cache_release(page); + if (release_page) + page_cache_release(page);
if (ret) { ret = -EFAULT; @@ -697,6 +708,7 @@ i915_gem_shmem_pwrite(struct drm_device *dev, int shmem_page_offset, page_length, ret; int obj_do_bit17_swizzling, page_do_bit17_swizzling; int hit_slowpath = 0; + int release_page;
user_data = (char __user *) (uintptr_t) args->data_ptr; remain = args->size; @@ -721,10 +733,16 @@ i915_gem_shmem_pwrite(struct drm_device *dev, if ((shmem_page_offset + page_length) > PAGE_SIZE) page_length = PAGE_SIZE - shmem_page_offset;
- page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); - if (IS_ERR(page)) { - ret = PTR_ERR(page); - goto out; + if (obj->pages) { + page = obj->pages[offset >> PAGE_SHIFT]; + release_page = 0; + } else { + page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); + if (IS_ERR(page)) { + ret = PTR_ERR(page); + goto out; + } + release_page = 1; }
page_do_bit17_swizzling = (page_to_phys(page) & (1 << 17)) == 0; @@ -741,6 +759,9 @@ i915_gem_shmem_pwrite(struct drm_device *dev, }
hit_slowpath = 1; + if (!release_page) + page_cache_get(page); + release_page = 1;
mutex_unlock(&dev->struct_mutex);
@@ -759,7 +780,8 @@ i915_gem_shmem_pwrite(struct drm_device *dev, next_page: set_page_dirty(page); mark_page_accessed(page); - page_cache_release(page); + if (release_page) + page_cache_release(page);
if (ret) { ret = -EFAULT;