[Mesa-dev] [PATCH] winsys/amdgpu: add a fast exit path into amdgpu_cs_add_buffer

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

The time spent in the function dropped by 37% for torcs.
---
 src/gallium/winsys/amdgpu/drm/amdgpu_cs.c | 16 ++++++++++++++++
 src/gallium/winsys/amdgpu/drm/amdgpu_cs.h |  5 +++++
 2 files changed, 21 insertions(+)

diff --git a/src/gallium/winsys/amdgpu/drm/amdgpu_cs.c b/src/gallium/winsys/amdgpu/drm/amdgpu_cs.c
index 0bc4ce9..2a1b932 100644
--- a/src/gallium/winsys/amdgpu/drm/amdgpu_cs.c
+++ b/src/gallium/winsys/amdgpu/drm/amdgpu_cs.c
@@ -437,40 +437,54 @@ static unsigned amdgpu_cs_add_buffer(struct radeon_winsys_cs *rcs,
 {
    /* Don't use the "domains" parameter. Amdgpu doesn't support changing
     * the buffer placement during command submission.
     */
    struct amdgpu_cs *acs = amdgpu_cs(rcs);
    struct amdgpu_cs_context *cs = acs->csc;
    struct amdgpu_winsys_bo *bo = (struct amdgpu_winsys_bo*)buf;
    struct amdgpu_cs_buffer *buffer;
    int index;
 
+   /* Fast exit for no-op calls.
+    * This is very effective with suballocators and linear uploaders that
+    * are outside of the winsys.
+    */
+   if (bo == cs->last_added_bo &&
+       (usage & cs->last_added_bo_usage) == usage &&
+       (1ull << priority) & cs->last_added_bo_priority_usage)
+      return cs->last_added_bo_index;
+
    if (!bo->bo) {
       index = amdgpu_lookup_or_add_slab_buffer(acs, bo);
       if (index < 0)
          return 0;
 
       buffer = &cs->slab_buffers[index];
       buffer->usage |= usage;
 
       usage &= ~RADEON_USAGE_SYNCHRONIZED;
       index = buffer->u.slab.real_idx;
    } else {
       index = amdgpu_lookup_or_add_real_buffer(acs, bo);
       if (index < 0)
          return 0;
    }
 
    buffer = &cs->real_buffers[index];
    buffer->u.real.priority_usage |= 1llu << priority;
    buffer->usage |= usage;
    cs->flags[index] = MAX2(cs->flags[index], priority / 4);
+
+   cs->last_added_bo = bo;
+   cs->last_added_bo_index = index;
+   cs->last_added_bo_usage = buffer->usage;
+   cs->last_added_bo_priority_usage = buffer->u.real.priority_usage;
    return index;
 }
 
 static bool amdgpu_ib_new_buffer(struct amdgpu_winsys *ws, struct amdgpu_ib *ib)
 {
    struct pb_buffer *pb;
    uint8_t *mapped;
    unsigned buffer_size;
 
    /* Always create a buffer that is at least as large as the maximum seen IB
@@ -638,20 +652,21 @@ static bool amdgpu_init_cs_context(struct amdgpu_cs_context *cs,
 
    default:
    case RING_GFX:
       cs->request.ip_type = AMDGPU_HW_IP_GFX;
       break;
    }
 
    for (i = 0; i < ARRAY_SIZE(cs->buffer_indices_hashlist); i++) {
       cs->buffer_indices_hashlist[i] = -1;
    }
+   cs->last_added_bo = NULL;
 
    cs->request.number_of_ibs = 1;
    cs->request.ibs = &cs->ib[IB_MAIN];
 
    cs->ib[IB_CONST].flags = AMDGPU_IB_FLAG_CE;
    cs->ib[IB_CONST_PREAMBLE].flags = AMDGPU_IB_FLAG_CE |
                                      AMDGPU_IB_FLAG_PREAMBLE;
 
    return true;
 }
@@ -669,20 +684,21 @@ static void amdgpu_cs_context_cleanup(struct amdgpu_cs_context *cs)
       amdgpu_winsys_bo_reference(&cs->slab_buffers[i].bo, NULL);
    }
 
    cs->num_real_buffers = 0;
    cs->num_slab_buffers = 0;
    amdgpu_fence_reference(&cs->fence, NULL);
 
    for (i = 0; i < ARRAY_SIZE(cs->buffer_indices_hashlist); i++) {
       cs->buffer_indices_hashlist[i] = -1;
    }
+   cs->last_added_bo = NULL;
 }
 
 static void amdgpu_destroy_cs_context(struct amdgpu_cs_context *cs)
 {
    amdgpu_cs_context_cleanup(cs);
    FREE(cs->flags);
    FREE(cs->real_buffers);
    FREE(cs->handles);
    FREE(cs->slab_buffers);
    FREE(cs->request.dependencies);
diff --git a/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h b/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h
index 90b9e83..495d55b 100644
--- a/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h
+++ b/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h
@@ -87,20 +87,25 @@ struct amdgpu_cs_context {
    amdgpu_bo_handle            *handles;
    uint8_t                     *flags;
    struct amdgpu_cs_buffer     *real_buffers;
 
    unsigned                    num_slab_buffers;
    unsigned                    max_slab_buffers;
    struct amdgpu_cs_buffer     *slab_buffers;
 
    int                         buffer_indices_hashlist[4096];
 
+   struct amdgpu_winsys_bo     *last_added_bo;
+   unsigned                    last_added_bo_index;
+   unsigned                    last_added_bo_usage;
+   uint64_t                    last_added_bo_priority_usage;
+
    unsigned                    max_dependencies;
 
    struct pipe_fence_handle    *fence;
 
    /* the error returned from cs_flush for non-async submissions */
    int                         error_code;
 };
 
 struct amdgpu_cs {
    struct amdgpu_ib main; /* must be first because this is inherited */
-- 
2.7.4