[PATCH] drm: Apply kref_put_mutex() optimisations to drm_gem_object_unreference_unlocked()
We can apply the same optimisation tricks as kref_put_mutex() in our local equivalent function. However, we have a different locking semantic (we unlock ourselves, in kref_put_mutex() the callee unlocks) so that we can use the same callbacks for both locked and unlocked kref_put()s and so can not simply convert to using kref_put_mutex() directly.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk --- include/drm/drmP.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/drm/drmP.h b/include/drm/drmP.h index 4b518e0..ee2ef27 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -1626,10 +1626,12 @@ drm_gem_object_unreference(struct drm_gem_object *obj) static inline void drm_gem_object_unreference_unlocked(struct drm_gem_object *obj) { - if (obj != NULL) { + if (obj && !atomic_add_unless(&obj->refcount.refcount, -1, 1)) { struct drm_device *dev = obj->dev; + mutex_lock(&dev->struct_mutex); - kref_put(&obj->refcount, drm_gem_object_free); + if (likely(atomic_dec_and_test(&obj->refcount.refcount))) + drm_gem_object_free(&obj->refcount); mutex_unlock(&dev->struct_mutex); } }
On Tue, Aug 06, 2013 at 09:59:46AM +0100, Chris Wilson wrote:
We can apply the same optimisation tricks as kref_put_mutex() in our local equivalent function. However, we have a different locking semantic (we unlock ourselves, in kref_put_mutex() the callee unlocks) so that we can use the same callbacks for both locked and unlocked kref_put()s and so can not simply convert to using kref_put_mutex() directly.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk
I think longterm we want to move to delayed free callbacks (similar to how fput works) since the locking with dma-buf and all will simply get too hairy. But for now this is a neat optimization imo, so
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
include/drm/drmP.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/drm/drmP.h b/include/drm/drmP.h index 4b518e0..ee2ef27 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -1626,10 +1626,12 @@ drm_gem_object_unreference(struct drm_gem_object *obj) static inline void drm_gem_object_unreference_unlocked(struct drm_gem_object *obj) {
- if (obj != NULL) {
- if (obj && !atomic_add_unless(&obj->refcount.refcount, -1, 1)) { struct drm_device *dev = obj->dev;
- mutex_lock(&dev->struct_mutex);
kref_put(&obj->refcount, drm_gem_object_free);
if (likely(atomic_dec_and_test(&obj->refcount.refcount)))drm_gem_object_free(&obj->refcount);}
1.8.4.rc1
dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel
On Tue, Aug 06, 2013 at 11:27:50PM +0200, Daniel Vetter wrote:
On Tue, Aug 06, 2013 at 09:59:46AM +0100, Chris Wilson wrote:
We can apply the same optimisation tricks as kref_put_mutex() in our local equivalent function. However, we have a different locking semantic (we unlock ourselves, in kref_put_mutex() the callee unlocks) so that we can use the same callbacks for both locked and unlocked kref_put()s and so can not simply convert to using kref_put_mutex() directly.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk
I think longterm we want to move to delayed free callbacks (similar to how fput works) since the locking with dma-buf and all will simply get too hairy. But for now this is a neat optimization imo, so
I have bad memories of delayed free batching up several thousand small bo. *shudder* -Chris
dri-devel@lists.freedesktop.org
-
Chris Wilson -
Daniel Vetter