Hi Chris On Mon, Sep 26, 2016 at 10:44 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > Currently we use a linear walk to lookup a handle and return a dma-buf, > and vice versa. A long overdue TODO task is to convert that to a > hashtable. Since the initial implementation of dma-buf/prime, we now > have resizeable hashtables we can use (and now a future task is to RCU > enable the lookup!). However, this patch opts to use an rbtree instead > to provide O(lgN) lookups (and insertion, deletion). rbtrees were chosen > over using the RCU backed resizable hashtable to firstly avoid the > reallocations (rbtrees can be embedded entirely within the parent > struct) and to favour simpler code with predictable worst case > behaviour. In simple testing, the difference between using the constant > lookup and insertion of the rhashtable and the rbtree was less than 10% > of the wall time (igt/benchmarks/prime_lookup) - both are dramatic > improvements over the existing linear lists. > > v2: Favour rbtree over rhashtable > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94631 > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Sean Paul <seanpaul@xxxxxxxxxxxx> > Cc: David Herrmann <dh.herrmann@xxxxxxxxx> > --- > drivers/gpu/drm/drm_prime.c | 85 +++++++++++++++++++++++++++++++++++++++------ > include/drm/drmP.h | 5 +-- > 2 files changed, 77 insertions(+), 13 deletions(-) Thanks for doing the benchmark and rewriting it with rb-trees. I think the lack of error-handling is a big plus here. Anyway, this is: Reviewed-by: David Herrmann <dh.herrmann@xxxxxxxxx> Your tree-traversals are a bit inconsistent in how you order your iterator against the element to lookup in your conditions, but.. meh. A big WARN_ON on conflicts might not hurt either. But looks all good. Thanks David > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > index 780589b420a4..57201d68cf61 100644 > --- a/drivers/gpu/drm/drm_prime.c > +++ b/drivers/gpu/drm/drm_prime.c > @@ -28,6 +28,7 @@ > > #include <linux/export.h> > #include <linux/dma-buf.h> > +#include <linux/rbtree.h> > #include <drm/drmP.h> > #include <drm/drm_gem.h> > > @@ -61,9 +62,11 @@ > */ > > struct drm_prime_member { > - struct list_head entry; > struct dma_buf *dma_buf; > uint32_t handle; > + > + struct rb_node dmabuf_rb; > + struct rb_node handle_rb; > }; > > struct drm_prime_attachment { > @@ -75,6 +78,7 @@ static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv, > struct dma_buf *dma_buf, uint32_t handle) > { > struct drm_prime_member *member; > + struct rb_node **p, *rb; > > member = kmalloc(sizeof(*member), GFP_KERNEL); > if (!member) > @@ -83,18 +87,56 @@ static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv, > get_dma_buf(dma_buf); > member->dma_buf = dma_buf; > member->handle = handle; > - list_add(&member->entry, &prime_fpriv->head); > + > + rb = NULL; > + p = &prime_fpriv->dmabufs.rb_node; > + while (*p) { > + struct drm_prime_member *pos; > + > + rb = *p; > + pos = rb_entry(rb, struct drm_prime_member, dmabuf_rb); > + if (dma_buf > pos->dma_buf) > + p = &rb->rb_right; > + else > + p = &rb->rb_left; > + } > + rb_link_node(&member->dmabuf_rb, rb, p); > + rb_insert_color(&member->dmabuf_rb, &prime_fpriv->dmabufs); > + > + rb = NULL; > + p = &prime_fpriv->handles.rb_node; > + while (*p) { > + struct drm_prime_member *pos; > + > + rb = *p; > + pos = rb_entry(rb, struct drm_prime_member, handle_rb); > + if (handle > pos->handle) > + p = &rb->rb_right; > + else > + p = &rb->rb_left; > + } > + rb_link_node(&member->handle_rb, rb, p); > + rb_insert_color(&member->handle_rb, &prime_fpriv->handles); > + > return 0; > } > > static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv, > uint32_t handle) > { > - struct drm_prime_member *member; > + struct rb_node *rb; > + > + rb = prime_fpriv->handles.rb_node; > + while (rb) { > + struct drm_prime_member *member; > > - list_for_each_entry(member, &prime_fpriv->head, entry) { > + member = rb_entry(rb, struct drm_prime_member, handle_rb); > if (member->handle == handle) > return member->dma_buf; > + else if (member->handle < handle) > + rb = rb->rb_right; > + else > + rb = rb->rb_left; > } > > return NULL; > @@ -104,14 +146,23 @@ static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpri > struct dma_buf *dma_buf, > uint32_t *handle) > { > - struct drm_prime_member *member; > + struct rb_node *rb; > + > + rb = prime_fpriv->dmabufs.rb_node; > + while (rb) { > + struct drm_prime_member *member; > > - list_for_each_entry(member, &prime_fpriv->head, entry) { > + member = rb_entry(rb, struct drm_prime_member, dmabuf_rb); > if (member->dma_buf == dma_buf) { > *handle = member->handle; > return 0; > + } else if (member->dma_buf < dma_buf) { > + rb = rb->rb_right; > + } else { > + rb = rb->rb_left; > } > } > + > return -ENOENT; > } > > @@ -166,13 +217,24 @@ static void drm_gem_map_detach(struct dma_buf *dma_buf, > void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpriv, > struct dma_buf *dma_buf) > { > - struct drm_prime_member *member, *safe; > + struct rb_node *rb; > > - list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) { > + rb = prime_fpriv->dmabufs.rb_node; > + while (rb) { > + struct drm_prime_member *member; > + > + member = rb_entry(rb, struct drm_prime_member, dmabuf_rb); > if (member->dma_buf == dma_buf) { > + rb_erase(&member->handle_rb, &prime_fpriv->handles); > + rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs); > + > dma_buf_put(dma_buf); > - list_del(&member->entry); > kfree(member); > + return; > + } else if (member->dma_buf < dma_buf) { > + rb = rb->rb_right; > + } else { > + rb = rb->rb_left; > } > } > } > @@ -759,12 +821,13 @@ EXPORT_SYMBOL(drm_prime_gem_destroy); > > void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv) > { > - INIT_LIST_HEAD(&prime_fpriv->head); > mutex_init(&prime_fpriv->lock); > + prime_fpriv->dmabufs = RB_ROOT; > + prime_fpriv->handles = RB_ROOT; > } > > void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv) > { > /* by now drm_gem_release should've made sure the list is empty */ > - WARN_ON(!list_empty(&prime_fpriv->head)); > + WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs)); > } > diff --git a/include/drm/drmP.h b/include/drm/drmP.h > index c53dc90942e0..289207f12adb 100644 > --- a/include/drm/drmP.h > +++ b/include/drm/drmP.h > @@ -51,6 +51,7 @@ > #include <linux/platform_device.h> > #include <linux/poll.h> > #include <linux/ratelimit.h> > +#include <linux/rbtree.h> > #include <linux/sched.h> > #include <linux/slab.h> > #include <linux/types.h> > @@ -371,10 +372,10 @@ struct drm_pending_event { > we deliver the event, for tracing only */ > }; > > -/* initial implementaton using a linked list - todo hashtab */ > struct drm_prime_file_private { > - struct list_head head; > struct mutex lock; > + struct rb_root dmabufs; > + struct rb_root handles; > }; > > /** File private data */ > -- > 2.9.3 > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
