[Mesa-dev] [PATCH] i965: Issue perf_debug messages for unsynchronized maps on !LLC systems.

[Kenneth Graunke]

We haven't implemented proper unsynchronized map support on !LLC systems
(pre-SNB, Atom).  MapBufferRange with GL_MAP_UNSYNCHRONIZE_BIT will
actually do a synchronized map, probably killing performance.

Also warn on BufferSubData, when we should be doing an unsynchronized
upload, but instead have to do a synchronous map.

v2: Only complain if the buffer is actually busy - we use unsynchronized
    maps internally for vertex upload and such, but expect those to not
    be busy.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/intel_buffer_objects.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_buffer_objects.c b/src/mesa/drivers/dri/i965/intel_buffer_objects.c
index f2d2bcb..39a7147 100644
--- a/src/mesa/drivers/dri/i965/intel_buffer_objects.c
+++ b/src/mesa/drivers/dri/i965/intel_buffer_objects.c
@@ -254,9 +254,9 @@ brw_buffer_subdata(struct gl_context *ctx,
     * (otherwise, an app that might occasionally stall but mostly not will end
     * up with blitting all the time, at the cost of bandwidth)
     */
-   if (brw->has_llc) {
-      if (offset + size <= intel_obj->gpu_active_start ||
-          intel_obj->gpu_active_end <= offset) {
+   if (offset + size <= intel_obj->gpu_active_start ||
+       intel_obj->gpu_active_end <= offset) {
+      if (brw->has_llc) {
          drm_intel_gem_bo_map_unsynchronized(intel_obj->buffer);
          memcpy(intel_obj->buffer->virtual + offset, data, size);
          drm_intel_bo_unmap(intel_obj->buffer);
@@ -264,6 +264,8 @@ brw_buffer_subdata(struct gl_context *ctx,
          if (intel_obj->gpu_active_end > intel_obj->gpu_active_start)
             intel_obj->prefer_stall_to_blit = true;
          return;
+      } else {
+         perf_debug("BufferSubData could be unsynchronized, but !LLC doesn't support it yet\n");
       }
    }
 
@@ -437,9 +439,13 @@ brw_map_buffer_range(struct gl_context *ctx,
       return obj->Mappings[index].Pointer;
    }
 
-   if (access & GL_MAP_UNSYNCHRONIZED_BIT)
+   if (access & GL_MAP_UNSYNCHRONIZED_BIT) {
+      if (!brw->has_llc && brw->perf_debug &&
+          drm_intel_bo_busy(intel_obj->buffer)) {
+         perf_debug("MapBufferRange with GL_MAP_UNSYNCHRONIZED_BIT stalling (it's actually synchronized on non-LLC platforms)\n");
+      }
       drm_intel_gem_bo_map_unsynchronized(intel_obj->buffer);
-   else if (!brw->has_llc && (!(access & GL_MAP_READ_BIT) ||
+   } else if (!brw->has_llc && (!(access & GL_MAP_READ_BIT) ||
                               (access & GL_MAP_PERSISTENT_BIT))) {
       drm_intel_gem_bo_map_gtt(intel_obj->buffer);
       mark_buffer_inactive(intel_obj);
-- 
2.1.2