st/mesa: optimize constant buffer uploads

The overhead of resource_create, transfer_inline_write, and resource_destroy
to upload constant data is very visible with some apps in sysprof, and
as such should be eliminated.

My approach uses a user buffer to pass a pointer to a driver. This gives
the driver the freedom it needs to take the fast path, which may differ
for each driver.

This commit addresses the same issue as Jakob's one that suballocates out
of a big constant buffer, but it also eliminates the copy to the buffer.

diff --git a/src/mesa/state_tracker/st_atom_constbuf.c b/src/mesa/state_tracker/st_atom_constbuf.c
index f1d08a3e1665e5cdb118eec3c6828193a686e971..05667a743053b59b2a751fd7b8a3cc220dab67e5 100644 (file)
--- a/src/mesa/state_tracker/st_atom_constbuf.c
+++ b/src/mesa/state_tracker/st_atom_constbuf.c
@@ -56,7 +56,6 @@ void st_upload_constants( struct st_context *st,
                           unsigned shader_type)
 {
    struct pipe_context *pipe = st->pipe;
-   struct pipe_resource **cbuf = &st->state.constants[shader_type];
 
    assert(shader_type == PIPE_SHADER_VERTEX ||
           shader_type == PIPE_SHADER_FRAGMENT ||
@@ -64,6 +63,7 @@ void st_upload_constants( struct st_context *st,
 
    /* update constants */
    if (params && params->NumParameters) {
+      struct pipe_resource *cbuf;
       const uint paramBytes = params->NumParameters * sizeof(GLfloat) * 4;
 
       /* Update the constants which come from fixed-function state, such as
@@ -75,11 +75,12 @@ void st_upload_constants( struct st_context *st,
 
       /* We always need to get a new buffer, to keep the drivers simple and
        * avoid gratuitous rendering synchronization.
+       * Let's use a user buffer to avoid an unnecessary copy.
        */
-      pipe_resource_reference(cbuf, NULL );
-      *cbuf = pipe_buffer_create(pipe->screen,
-                                PIPE_BIND_CONSTANT_BUFFER,
-                                paramBytes );
+      cbuf = pipe_user_buffer_create(pipe->screen,
+                                     params->ParameterValues,
+                                     paramBytes,
+                                     PIPE_BIND_CONSTANT_BUFFER);
 
       if (ST_DEBUG & DEBUG_CONSTANTS) {
         debug_printf("%s(shader=%d, numParams=%d, stateFlags=0x%x)\n", 
@@ -88,17 +89,15 @@ void st_upload_constants( struct st_context *st,
          _mesa_print_parameter_list(params);
       }
 
-      /* load Mesa constants into the constant buffer */
-      pipe_buffer_write(st->pipe, *cbuf,
-                                   0, paramBytes,
-                                   params->ParameterValues);
+      st->pipe->set_constant_buffer(st->pipe, shader_type, 0, cbuf);
+      pipe_resource_reference(&cbuf, NULL);
 
-      st->pipe->set_constant_buffer(st->pipe, shader_type, 0, *cbuf);
+      st->state.constants[shader_type].ptr = params->ParameterValues;
+      st->state.constants[shader_type].size = paramBytes;
    }
-   else if (*cbuf) {
-      st->constants.tracked_state[shader_type].dirty.mesa = 0x0;
-
-      pipe_resource_reference(cbuf, NULL);
+   else if (st->state.constants[shader_type].ptr) {
+      st->state.constants[shader_type].ptr = NULL;
+      st->state.constants[shader_type].size = 0;
       st->pipe->set_constant_buffer(st->pipe, shader_type, 0, NULL);
    }
 }

diff --git a/src/mesa/state_tracker/st_context.c b/src/mesa/state_tracker/st_context.c
index 21bb91f47a8eacb94ab6cf9f089284fa2215821f..c7f3949bf9e64b827e5b8a08f918d150a479f759 100644 (file)
--- a/src/mesa/state_tracker/st_context.c
+++ b/src/mesa/state_tracker/st_context.c
@@ -207,12 +207,6 @@ static void st_destroy_context_priv( struct st_context *st )
       pipe_sampler_view_reference(&st->state.sampler_views[i], NULL);
    }
 
-   for (i = 0; i < Elements(st->state.constants); i++) {
-      if (st->state.constants[i]) {
-         pipe_resource_reference(&st->state.constants[i], NULL);
-      }
-   }
-
    if (st->default_texture) {
       st->ctx->Driver.DeleteTexture(st->ctx, st->default_texture);
       st->default_texture = NULL;
@@ -245,7 +239,6 @@ void st_destroy_context( struct st_context *st )
 
    for (i = 0; i < PIPE_SHADER_TYPES; i++) {
       pipe->set_constant_buffer(pipe, i, 0, NULL);
-      pipe_resource_reference(&st->state.constants[i], NULL);
    }
 
    _mesa_delete_program_cache(st->ctx, st->pixel_xfer.cache);

diff --git a/src/mesa/state_tracker/st_context.h b/src/mesa/state_tracker/st_context.h
index 1fd80053c1b6d9751485ccb446e0a0d1ef577639..f20eb54e97108d28fd69137d634808f0e130972a 100644 (file)
--- a/src/mesa/state_tracker/st_context.h
+++ b/src/mesa/state_tracker/st_context.h
@@ -92,7 +92,10 @@ struct st_context
       struct pipe_sampler_state             samplers[PIPE_MAX_SAMPLERS];
       struct pipe_sampler_state             *sampler_list[PIPE_MAX_SAMPLERS];
       struct pipe_clip_state clip;
-      struct pipe_resource *constants[PIPE_SHADER_TYPES];
+      struct {
+         void *ptr;
+         unsigned size;
+      } constants[PIPE_SHADER_TYPES];
       struct pipe_framebuffer_state framebuffer;
       struct pipe_sampler_view *sampler_views[PIPE_MAX_SAMPLERS];
       struct pipe_scissor_state scissor;

diff --git a/src/mesa/state_tracker/st_draw_feedback.c b/src/mesa/state_tracker/st_draw_feedback.c
index da67c713710e5cdf6069887e816e7eb8c96ae217..05917992d6e95983205060138fe96fb2f69d2612 100644 (file)
--- a/src/mesa/state_tracker/st_draw_feedback.c
+++ b/src/mesa/state_tracker/st_draw_feedback.c
@@ -109,9 +109,7 @@ st_feedback_draw_vbo(struct gl_context *ctx,
    struct pipe_index_buffer ibuffer;
    struct pipe_transfer *vb_transfer[PIPE_MAX_ATTRIBS];
    struct pipe_transfer *ib_transfer = NULL;
-   struct pipe_transfer *cb_transfer;
    GLuint attr, i;
-   ubyte *mapped_constants;
    const void *mapped_indices = NULL;
 
    assert(draw);
@@ -242,14 +240,10 @@ st_feedback_draw_vbo(struct gl_context *ctx,
       draw_set_mapped_index_buffer(draw, mapped_indices);
    }
 
-   /* map constant buffers */
-   mapped_constants = pipe_buffer_map(pipe,
-                                      st->state.constants[PIPE_SHADER_VERTEX],
-                                      PIPE_TRANSFER_READ,
-                                     &cb_transfer);
+   /* set the constant buffer */
    draw_set_mapped_constant_buffer(st->draw, PIPE_SHADER_VERTEX, 0,
-                                   mapped_constants,
-                                   st->state.constants[PIPE_SHADER_VERTEX]->width0);
+                                   st->state.constants[PIPE_SHADER_VERTEX].ptr,
+                                   st->state.constants[PIPE_SHADER_VERTEX].size);
 
 
    /* draw here */
@@ -258,9 +252,6 @@ st_feedback_draw_vbo(struct gl_context *ctx,
    }
 
 
-   /* unmap constant buffers */
-   pipe_buffer_unmap(pipe, cb_transfer);
-
    /*
     * unmap vertex/index buffers
     */