panfrost: Make transient allocation rely on the BO cache

Right now, the transient memory allocator implements its own BO caching
mechanism, which is not really needed since we already have a generic
BO cache. Let's simplify things a bit.

Signed-off-by: Boris Brezillon <[email protected]>
Reviewed-by: Alyssa Rosenzweig <[email protected]>

5 files changed, 16 insertions, 104 deletions

diff --git a/src/gallium/drivers/panfrost/pan_allocate.c b/src/gallium/drivers/panfrost/pan_allocate.c
index d8a594551c7..a22b1a5a88d 100644
--- a/src/gallium/drivers/panfrost/pan_allocate.c
+++ b/src/gallium/drivers/panfrost/pan_allocate.c
@@ -34,27 +34,6 @@
 /* TODO: What does this actually have to be? */
 #define ALIGNMENT 128
 
-/* Allocate a new transient slab */
-
-static struct panfrost_bo *
-panfrost_create_slab(struct panfrost_screen *screen, unsigned *index)
-{
-        /* Allocate a new slab on the screen */
-
-        struct panfrost_bo **new =
-                util_dynarray_grow(&screen->transient_bo,
-                                struct panfrost_bo *, 1);
-
-        struct panfrost_bo *alloc = panfrost_drm_create_bo(screen, TRANSIENT_SLAB_SIZE, 0);
-
-        *new = alloc;
-
-        /* Return the BO as well as the index we just added */
-
-        *index = util_dynarray_num_elements(&screen->transient_bo, void *) - 1;
-        return alloc;
-}
-
 /* Transient command stream pooling: command stream uploads try to simply copy
  * into whereever we left off. If there isn't space, we allocate a new entry
  * into the pool and copy there */
@@ -72,59 +51,32 @@ panfrost_allocate_transient(struct panfrost_context *ctx, size_t sz)
         struct panfrost_bo *bo = NULL;
 
         unsigned offset = 0;
-        bool update_offset = false;
 
-        pthread_mutex_lock(&screen->transient_lock);
-        bool has_current = batch->transient_indices.size;
         bool fits_in_current = (batch->transient_offset + sz) < TRANSIENT_SLAB_SIZE;
 
-        if (likely(has_current && fits_in_current)) {
-                /* We can reuse the topmost BO, so get it */
-                unsigned idx = util_dynarray_top(&batch->transient_indices, unsigned);
-                bo = pan_bo_for_index(screen, idx);
+        if (likely(batch->transient_bo && fits_in_current)) {
+                /* We can reuse the current BO, so get it */
+                bo = batch->transient_bo;
 
                 /* Use the specified offset */
                 offset = batch->transient_offset;
-                update_offset = true;
-        } else if (sz < TRANSIENT_SLAB_SIZE) {
-                /* We can't reuse the topmost BO, but we can get a new one.
-                 * First, look for a free slot */
-
-                unsigned count = util_dynarray_num_elements(&screen->transient_bo, void *);
-                unsigned index = 0;
-
-                unsigned free = __bitset_ffs(
-                                screen->free_transient,
-                                count / BITSET_WORDBITS);
-
-                if (likely(free)) {
-                        /* Use this one */
-                        index = free - 1;
-
-                        /* It's ours, so no longer free */
-                        BITSET_CLEAR(screen->free_transient, index);
-
-                        /* Grab the BO */
-                        bo = pan_bo_for_index(screen, index);
-                } else {
-                        /* Otherwise, create a new BO */
-                        bo = panfrost_create_slab(screen, &index);
-                }
-
-                panfrost_batch_add_bo(batch, bo);
-
-                /* Remember we created this */
-                util_dynarray_append(&batch->transient_indices, unsigned, index);
-
-                update_offset = true;
+                batch->transient_offset = offset + sz;
         } else {
-                /* Create a new BO and reference it */
-                bo = panfrost_drm_create_bo(screen, ALIGN_POT(sz, 4096), 0);
+                size_t bo_sz = sz < TRANSIENT_SLAB_SIZE ?
+                               TRANSIENT_SLAB_SIZE : ALIGN_POT(sz, 4096);
+
+                /* We can't reuse the current BO, but we can create a new one. */
+                bo = panfrost_drm_create_bo(screen, bo_sz, 0);
                 panfrost_batch_add_bo(batch, bo);
 
                 /* Creating a BO adds a reference, and then the job adds a
                  * second one. So we need to pop back one reference */
                 panfrost_bo_unreference(&screen->base, bo);
+
+                if (sz < TRANSIENT_SLAB_SIZE) {
+                        batch->transient_bo = bo;
+                        batch->transient_offset = offset + sz;
+                }
         }
 
         struct panfrost_transfer ret = {
@@ -132,10 +84,6 @@ panfrost_allocate_transient(struct panfrost_context *ctx, size_t sz)
                 .gpu = bo->gpu + offset,
         };
 
-        if (update_offset)
-                batch->transient_offset = offset + sz;
-        pthread_mutex_unlock(&screen->transient_lock);
-
         return ret;
 
 }
diff --git a/src/gallium/drivers/panfrost/pan_job.c b/src/gallium/drivers/panfrost/pan_job.c
index 0d19c2b4c5c..58b494108e2 100644
--- a/src/gallium/drivers/panfrost/pan_job.c
+++ b/src/gallium/drivers/panfrost/pan_job.c
@@ -48,7 +48,6 @@ panfrost_create_batch(struct panfrost_context *ctx)
 
         util_dynarray_init(&batch->headers, batch);
         util_dynarray_init(&batch->gpu_headers, batch);
-        util_dynarray_init(&batch->transient_indices, batch);
 
         return batch;
 }
@@ -66,16 +65,6 @@ panfrost_free_batch(struct panfrost_batch *batch)
                 panfrost_bo_unreference(ctx->base.screen, bo);
         }
 
-        /* Free up the transient BOs we're sitting on */
-        struct panfrost_screen *screen = pan_screen(ctx->base.screen);
-
-        pthread_mutex_lock(&screen->transient_lock);
-        util_dynarray_foreach(&batch->transient_indices, unsigned, index) {
-                /* Mark it free */
-                BITSET_SET(screen->free_transient, *index);
-        }
-        pthread_mutex_unlock(&screen->transient_lock);
-
         /* Unreference the polygon list */
         panfrost_bo_unreference(ctx->base.screen, batch->polygon_list);
 
diff --git a/src/gallium/drivers/panfrost/pan_job.h b/src/gallium/drivers/panfrost/pan_job.h
index 7e0b7b3f314..c9f48787121 100644
--- a/src/gallium/drivers/panfrost/pan_job.h
+++ b/src/gallium/drivers/panfrost/pan_job.h
@@ -107,8 +107,8 @@ struct panfrost_batch {
         /* BOs referenced -- will be used for flushing logic */
         struct set *bos;
 
-        /* Indices of transient BOs referenced */
-        struct util_dynarray transient_indices;
+        /* Current transient BO */
+	struct panfrost_bo *transient_bo;
 
         /* Within the topmost transient BO, how much has been used? */
         unsigned transient_offset;
diff --git a/src/gallium/drivers/panfrost/pan_screen.c b/src/gallium/drivers/panfrost/pan_screen.c
index bd826808fd6..5dcceac370d 100644
--- a/src/gallium/drivers/panfrost/pan_screen.c
+++ b/src/gallium/drivers/panfrost/pan_screen.c
@@ -543,7 +543,6 @@ panfrost_destroy_screen(struct pipe_screen *pscreen)
         struct panfrost_screen *screen = pan_screen(pscreen);
         panfrost_bo_cache_evict_all(screen);
         pthread_mutex_destroy(&screen->bo_cache_lock);
-        pthread_mutex_destroy(&screen->transient_lock);
         drmFreeVersion(screen->kernel_version);
         ralloc_free(screen);
 }
@@ -641,9 +640,6 @@ panfrost_create_screen(int fd, struct renderonly *ro)
                 return NULL;
         }
 
-        pthread_mutex_init(&screen->transient_lock, NULL);
-        util_dynarray_init(&screen->transient_bo, screen);
-
         pthread_mutex_init(&screen->bo_cache_lock, NULL);
         for (unsigned i = 0; i < ARRAY_SIZE(screen->bo_cache); ++i)
                 list_inithead(&screen->bo_cache[i]);
diff --git a/src/gallium/drivers/panfrost/pan_screen.h b/src/gallium/drivers/panfrost/pan_screen.h
index 11cbb72075a..7ed5193277a 100644
--- a/src/gallium/drivers/panfrost/pan_screen.h
+++ b/src/gallium/drivers/panfrost/pan_screen.h
@@ -105,17 +105,6 @@ struct panfrost_screen {
 
         struct renderonly *ro;
 
-        pthread_mutex_t transient_lock;
-
-        /* Transient memory management is based on borrowing fixed-size slabs
-         * off the screen (loaning them out to the batch). Dynamic array
-         * container of panfrost_bo */
-
-        struct util_dynarray transient_bo;
-
-        /* Set of free transient BOs */
-        BITSET_DECLARE(free_transient, MAX_TRANSIENT_SLABS);
-
         pthread_mutex_t bo_cache_lock;
 
         /* The BO cache is a set of buckets with power-of-two sizes ranging
@@ -131,16 +120,6 @@ pan_screen(struct pipe_screen *p)
         return (struct panfrost_screen *)p;
 }
 
-/* Get a transient BO off the screen given a
- * particular index */
-
-static inline struct panfrost_bo *
-pan_bo_for_index(struct panfrost_screen *screen, unsigned index)
-{
-        return *(util_dynarray_element(&screen->transient_bo,
-                                struct panfrost_bo *, index));
-}
-
 void
 panfrost_drm_allocate_slab(struct panfrost_screen *screen,
                            struct panfrost_memory *mem,