| Message ID | 1352122278-12896-4-git-send-email-thellstrom@vmware.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 11/05/2012 02:31 PM, Thomas Hellstrom wrote: > The mostly used lookup+get put+potential_destroy path of TTM objects > is converted to use RCU locks. This will substantially decrease the amount > of locked bus cycles during normal operation. > Since we use kfree_rcu to free the objects, no rcu synchronization is needed > at module unload time. > > Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> > --- > drivers/gpu/drm/ttm/ttm_object.c | 30 +++++++++++------------------- > drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 8 ++++---- > include/drm/ttm/ttm_object.h | 4 ++++ > include/linux/kref.h | 2 +- > 4 files changed, 20 insertions(+), 24 deletions(-) > > diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c > index c785787..9d7f674 100644 > --- a/drivers/gpu/drm/ttm/ttm_object.c > +++ b/drivers/gpu/drm/ttm/ttm_object.c > @@ -80,7 +80,7 @@ struct ttm_object_file { > */ > > struct ttm_object_device { > - rwlock_t object_lock; > + spinlock_t object_lock; > struct drm_open_hash object_hash; > atomic_t object_count; > struct ttm_mem_global *mem_glob; > @@ -157,12 +157,12 @@ int ttm_base_object_init(struct ttm_object_file *tfile, > base->refcount_release = refcount_release; > base->ref_obj_release = ref_obj_release; > base->object_type = object_type; > - write_lock(&tdev->object_lock); > + spin_lock(&tdev->object_lock); > kref_init(&base->refcount); > ret = drm_ht_just_insert_please(&tdev->object_hash, > &base->hash, > (unsigned long)base, 31, 0, 0); > - write_unlock(&tdev->object_lock); > + spin_unlock(&tdev->object_lock); > if (unlikely(ret != 0)) > goto out_err0; > > @@ -186,30 +186,22 @@ static void ttm_release_base(struct kref *kref) > container_of(kref, struct ttm_base_object, refcount); > struct ttm_object_device *tdev = base->tfile->tdev; > > + spin_lock(&tdev->object_lock); > (void)drm_ht_remove_item(&tdev->object_hash, &base->hash); > - write_unlock(&tdev->object_lock); > + spin_unlock(&tdev->object_lock); > if (base->refcount_release) { > ttm_object_file_unref(&base->tfile); > base->refcount_release(&base); > } > - write_lock(&tdev->object_lock); > } > > void ttm_base_object_unref(struct ttm_base_object **p_base) > { > struct ttm_base_object *base = *p_base; > - struct ttm_object_device *tdev = base->tfile->tdev; > > *p_base = NULL; > > - /* > - * Need to take the lock here to avoid racing with > - * users trying to look up the object. > - */ > - > - write_lock(&tdev->object_lock); > kref_put(&base->refcount, ttm_release_base); > - write_unlock(&tdev->object_lock); > } > EXPORT_SYMBOL(ttm_base_object_unref); > > @@ -221,14 +213,14 @@ struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile, > struct drm_hash_item *hash; > int ret; > > - read_lock(&tdev->object_lock); > + rcu_read_lock(); > ret = drm_ht_find_item(&tdev->object_hash, key, &hash); > > if (likely(ret == 0)) { > base = drm_hash_entry(hash, struct ttm_base_object, hash); > - kref_get(&base->refcount); > + ret = kref_get_unless_zero(&base->refcount); > } > - read_unlock(&tdev->object_lock); > + rcu_read_unlock(); > > if (unlikely(ret != 0)) > return NULL; > @@ -426,7 +418,7 @@ struct ttm_object_device *ttm_object_device_init(struct ttm_mem_global > return NULL; > > tdev->mem_glob = mem_glob; > - rwlock_init(&tdev->object_lock); > + spin_lock_init(&tdev->object_lock); > atomic_set(&tdev->object_count, 0); > ret = drm_ht_create(&tdev->object_hash, hash_order); > > @@ -444,9 +436,9 @@ void ttm_object_device_release(struct ttm_object_device **p_tdev) > > *p_tdev = NULL; > > - write_lock(&tdev->object_lock); > + spin_lock(&tdev->object_lock); > drm_ht_remove(&tdev->object_hash); > - write_unlock(&tdev->object_lock); > + spin_unlock(&tdev->object_lock); > > kfree(tdev); > } > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c > index da3c6b5..ae675c6 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c > @@ -351,7 +351,7 @@ static void vmw_user_context_free(struct vmw_resource *res) > container_of(res, struct vmw_user_context, res); > struct vmw_private *dev_priv = res->dev_priv; > > - kfree(ctx); > + ttm_base_object_kfree(ctx, base); > ttm_mem_global_free(vmw_mem_glob(dev_priv), > vmw_user_context_size); > } > @@ -1147,7 +1147,7 @@ static void vmw_user_surface_free(struct vmw_resource *res) > kfree(srf->offsets); > kfree(srf->sizes); > kfree(srf->snooper.image); > - kfree(user_srf); > + ttm_base_object_kfree(user_srf, base); > ttm_mem_global_free(vmw_mem_glob(dev_priv), size); > } > > @@ -1575,7 +1575,7 @@ static void vmw_user_dmabuf_destroy(struct ttm_buffer_object *bo) > { > struct vmw_user_dma_buffer *vmw_user_bo = vmw_user_dma_buffer(bo); > > - kfree(vmw_user_bo); > + ttm_base_object_kfree(vmw_user_bo, base); > } > > static void vmw_user_dmabuf_release(struct ttm_base_object **p_base) > @@ -1763,7 +1763,7 @@ static void vmw_user_stream_free(struct vmw_resource *res) > container_of(res, struct vmw_user_stream, stream.res); > struct vmw_private *dev_priv = res->dev_priv; > > - kfree(stream); > + ttm_base_object_kfree(stream, base); > ttm_mem_global_free(vmw_mem_glob(dev_priv), > vmw_user_stream_size); > } > diff --git a/include/drm/ttm/ttm_object.h b/include/drm/ttm/ttm_object.h > index b01c563..fc0cf06 100644 > --- a/include/drm/ttm/ttm_object.h > +++ b/include/drm/ttm/ttm_object.h > @@ -40,6 +40,7 @@ > #include <linux/list.h> > #include <drm/drm_hashtab.h> > #include <linux/kref.h> > +#include <linux/rcupdate.h> > #include <ttm/ttm_memory.h> > > /** > @@ -120,6 +121,7 @@ struct ttm_object_device; > */ > > struct ttm_base_object { > + struct rcu_head rhead; > struct drm_hash_item hash; > enum ttm_object_type object_type; > bool shareable; > @@ -268,4 +270,6 @@ extern struct ttm_object_device *ttm_object_device_init > > extern void ttm_object_device_release(struct ttm_object_device **p_tdev); > > +#define ttm_base_object_kfree(__object, __base)\ > + kfree_rcu(__object, __base.rhead) > #endif > diff --git a/include/linux/kref.h b/include/linux/kref.h > index fd16042..bae91d0 100644 > --- a/include/linux/kref.h > +++ b/include/linux/kref.h > @@ -117,7 +117,7 @@ static inline int kref_put_mutex(struct kref *kref, > * @kref: object. > * > * Return 0 if the increment succeeded. Otherwise return non-zero. > - > + * > * This function is intended to simplify locking around refcounting for > * objects that can be looked up from a lookup structure, and which are > * removed from that lookup structure in the object destructor. Hmm, This patch looks bad. I'll respin it. /Thomas
diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c index c785787..9d7f674 100644 --- a/drivers/gpu/drm/ttm/ttm_object.c +++ b/drivers/gpu/drm/ttm/ttm_object.c @@ -80,7 +80,7 @@ struct ttm_object_file { */ struct ttm_object_device { - rwlock_t object_lock; + spinlock_t object_lock; struct drm_open_hash object_hash; atomic_t object_count; struct ttm_mem_global *mem_glob; @@ -157,12 +157,12 @@ int ttm_base_object_init(struct ttm_object_file *tfile, base->refcount_release = refcount_release; base->ref_obj_release = ref_obj_release; base->object_type = object_type; - write_lock(&tdev->object_lock); + spin_lock(&tdev->object_lock); kref_init(&base->refcount); ret = drm_ht_just_insert_please(&tdev->object_hash, &base->hash, (unsigned long)base, 31, 0, 0); - write_unlock(&tdev->object_lock); + spin_unlock(&tdev->object_lock); if (unlikely(ret != 0)) goto out_err0; @@ -186,30 +186,22 @@ static void ttm_release_base(struct kref *kref) container_of(kref, struct ttm_base_object, refcount); struct ttm_object_device *tdev = base->tfile->tdev; + spin_lock(&tdev->object_lock); (void)drm_ht_remove_item(&tdev->object_hash, &base->hash); - write_unlock(&tdev->object_lock); + spin_unlock(&tdev->object_lock); if (base->refcount_release) { ttm_object_file_unref(&base->tfile); base->refcount_release(&base); } - write_lock(&tdev->object_lock); } void ttm_base_object_unref(struct ttm_base_object **p_base) { struct ttm_base_object *base = *p_base; - struct ttm_object_device *tdev = base->tfile->tdev; *p_base = NULL; - /* - * Need to take the lock here to avoid racing with - * users trying to look up the object. - */ - - write_lock(&tdev->object_lock); kref_put(&base->refcount, ttm_release_base); - write_unlock(&tdev->object_lock); } EXPORT_SYMBOL(ttm_base_object_unref); @@ -221,14 +213,14 @@ struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile, struct drm_hash_item *hash; int ret; - read_lock(&tdev->object_lock); + rcu_read_lock(); ret = drm_ht_find_item(&tdev->object_hash, key, &hash); if (likely(ret == 0)) { base = drm_hash_entry(hash, struct ttm_base_object, hash); - kref_get(&base->refcount); + ret = kref_get_unless_zero(&base->refcount); } - read_unlock(&tdev->object_lock); + rcu_read_unlock(); if (unlikely(ret != 0)) return NULL; @@ -426,7 +418,7 @@ struct ttm_object_device *ttm_object_device_init(struct ttm_mem_global return NULL; tdev->mem_glob = mem_glob; - rwlock_init(&tdev->object_lock); + spin_lock_init(&tdev->object_lock); atomic_set(&tdev->object_count, 0); ret = drm_ht_create(&tdev->object_hash, hash_order); @@ -444,9 +436,9 @@ void ttm_object_device_release(struct ttm_object_device **p_tdev) *p_tdev = NULL; - write_lock(&tdev->object_lock); + spin_lock(&tdev->object_lock); drm_ht_remove(&tdev->object_hash); - write_unlock(&tdev->object_lock); + spin_unlock(&tdev->object_lock); kfree(tdev); } diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c index da3c6b5..ae675c6 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c @@ -351,7 +351,7 @@ static void vmw_user_context_free(struct vmw_resource *res) container_of(res, struct vmw_user_context, res); struct vmw_private *dev_priv = res->dev_priv; - kfree(ctx); + ttm_base_object_kfree(ctx, base); ttm_mem_global_free(vmw_mem_glob(dev_priv), vmw_user_context_size); } @@ -1147,7 +1147,7 @@ static void vmw_user_surface_free(struct vmw_resource *res) kfree(srf->offsets); kfree(srf->sizes); kfree(srf->snooper.image); - kfree(user_srf); + ttm_base_object_kfree(user_srf, base); ttm_mem_global_free(vmw_mem_glob(dev_priv), size); } @@ -1575,7 +1575,7 @@ static void vmw_user_dmabuf_destroy(struct ttm_buffer_object *bo) { struct vmw_user_dma_buffer *vmw_user_bo = vmw_user_dma_buffer(bo); - kfree(vmw_user_bo); + ttm_base_object_kfree(vmw_user_bo, base); } static void vmw_user_dmabuf_release(struct ttm_base_object **p_base) @@ -1763,7 +1763,7 @@ static void vmw_user_stream_free(struct vmw_resource *res) container_of(res, struct vmw_user_stream, stream.res); struct vmw_private *dev_priv = res->dev_priv; - kfree(stream); + ttm_base_object_kfree(stream, base); ttm_mem_global_free(vmw_mem_glob(dev_priv), vmw_user_stream_size); } diff --git a/include/drm/ttm/ttm_object.h b/include/drm/ttm/ttm_object.h index b01c563..fc0cf06 100644 --- a/include/drm/ttm/ttm_object.h +++ b/include/drm/ttm/ttm_object.h @@ -40,6 +40,7 @@ #include <linux/list.h> #include <drm/drm_hashtab.h> #include <linux/kref.h> +#include <linux/rcupdate.h> #include <ttm/ttm_memory.h> /** @@ -120,6 +121,7 @@ struct ttm_object_device; */ struct ttm_base_object { + struct rcu_head rhead; struct drm_hash_item hash; enum ttm_object_type object_type; bool shareable; @@ -268,4 +270,6 @@ extern struct ttm_object_device *ttm_object_device_init extern void ttm_object_device_release(struct ttm_object_device **p_tdev); +#define ttm_base_object_kfree(__object, __base)\ + kfree_rcu(__object, __base.rhead) #endif diff --git a/include/linux/kref.h b/include/linux/kref.h index fd16042..bae91d0 100644 --- a/include/linux/kref.h +++ b/include/linux/kref.h @@ -117,7 +117,7 @@ static inline int kref_put_mutex(struct kref *kref, * @kref: object. * * Return 0 if the increment succeeded. Otherwise return non-zero. - + * * This function is intended to simplify locking around refcounting for * objects that can be looked up from a lookup structure, and which are * removed from that lookup structure in the object destructor.
The mostly used lookup+get put+potential_destroy path of TTM objects is converted to use RCU locks. This will substantially decrease the amount of locked bus cycles during normal operation. Since we use kfree_rcu to free the objects, no rcu synchronization is needed at module unload time. Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> --- drivers/gpu/drm/ttm/ttm_object.c | 30 +++++++++++------------------- drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 8 ++++---- include/drm/ttm/ttm_object.h | 4 ++++ include/linux/kref.h | 2 +- 4 files changed, 20 insertions(+), 24 deletions(-)