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| author | Thomas Hellstrom <thellstrom@vmware.com> | 2012-11-06 12:31:51 +0100 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2012-11-20 07:15:06 +0100 |
| commit | 6c1e963cc5771c93d4ed7aa8bdd4322a7c918e9b (patch) | |
| tree | 435fec38d156d82a0f7497431712f39f59141919 /drivers/gpu/drm/ttm | |
| parent | drm/ttm, drm/vmwgfx: Use RCU locking for object lookups v3 (diff) | |
| download | linux-6c1e963cc5771c93d4ed7aa8bdd4322a7c918e9b.tar.xz linux-6c1e963cc5771c93d4ed7aa8bdd4322a7c918e9b.zip | |
drm/ttm: Optimize reservation slightly
Reservation locking currently always takes place under the LRU spinlock.
Hence, strictly there is no need for an atomic_cmpxchg call; we can use
atomic_read followed by atomic_write since nobody else will ever reserve
without the lru spinlock held.
At least on Intel this should remove a locked bus cycle on successful
reserve.
Note that thit commit may be obsoleted by the cross-device reservation work.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/gpu/drm/ttm')
| -rw-r--r-- | drivers/gpu/drm/ttm/ttm_bo.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index d1e5326d442c..5f61f133b419 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -220,7 +220,7 @@ int ttm_bo_reserve_locked(struct ttm_buffer_object *bo, struct ttm_bo_global *glob = bo->glob; int ret; - while (unlikely(atomic_cmpxchg(&bo->reserved, 0, 1) != 0)) { + while (unlikely(atomic_read(&bo->reserved) != 0)) { /** * Deadlock avoidance for multi-bo reserving. */ @@ -249,6 +249,7 @@ int ttm_bo_reserve_locked(struct ttm_buffer_object *bo, return ret; } + atomic_set(&bo->reserved, 1); if (use_sequence) { /** * Wake up waiters that may need to recheck for deadlock, |