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.
v3: Unconditionaly grab a page reference when dropping
dev->struct_mutex to simplify the code-flow.
Signed-off-by: Daniel Vetter <daniel.vet...@ffwll.ch>
---
drivers/gpu/drm/i915/i915_gem.c | 42 +++++++++++++++++++++++++++-----------
1 files changed, 30 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0446c4c..0487889 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -321,6 +321,7 @@ 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;
@@ -355,10 +356,16 @@ 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 = obj_do_bit17_swizzling &&
@@ -378,7 +385,7 @@ i915_gem_shmem_pread(struct drm_device *dev,
}
hit_slowpath = 1;
-
+ page_cache_get(page);
mutex_unlock(&dev->struct_mutex);
vaddr = kmap(page);
@@ -397,9 +404,11 @@ i915_gem_shmem_pread(struct drm_device *dev,
kunmap(page);
mutex_lock(&dev->struct_mutex);
+ page_cache_release(page);
next_page:
mark_page_accessed(page);
- page_cache_release(page);
+ if (release_page)
+ page_cache_release(page);
if (ret) {
ret = -EFAULT;
@@ -680,6 +689,7 @@ 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;
@@ -704,10 +714,16 @@ 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 = obj_do_bit17_swizzling &&
@@ -725,7 +741,7 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
}
hit_slowpath = 1;
-
+ page_cache_get(page);
mutex_unlock(&dev->struct_mutex);
vaddr = kmap(page);
@@ -740,10 +756,12 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
kunmap(page);
mutex_lock(&dev->struct_mutex);
+ page_cache_release(page);
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;
--
1.7.7.5
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