intel: Use system memory for DYNAMIC_DRAW source objects

Dynamic draw buffers are used by clients for temporary arrays and for
uploading normal vertex arrays. By keeping the data in memory, we can
avoid reusing active buffer objects and reallocate them as they are
changed. This is important for Sandybridge which can not issue blits
within a batch and so ends up flushing the batch upon every update, that
is each batch only contains a single draw operation (if using dynamic
arrays or regular arrays from system memory).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 31 insertions, 20 deletions

diff --git a/src/mesa/drivers/dri/intel/intel_buffer_objects.c b/src/mesa/drivers/dri/intel/intel_buffer_objects.c
index d917161c4b..62e8d822c2 100644
--- a/src/mesa/drivers/dri/intel/intel_buffer_objects.c
+++ b/src/mesa/drivers/dri/intel/intel_buffer_objects.c
@@ -162,11 +162,15 @@ intel_bufferobj_data(struct gl_context * ctx,
    intel_obj->sys_buffer = NULL;
 
    if (size != 0) {
+      if (usage == GL_DYNAMIC_DRAW
 #ifdef I915
-      /* On pre-965, stick VBOs in system memory, as we're always doing swtnl
-       * with their contents anyway.
-       */
-      if (target == GL_ARRAY_BUFFER || target == GL_ELEMENT_ARRAY_BUFFER) {
+	  /* On pre-965, stick VBOs in system memory, as we're always doing
+	   * swtnl with their contents anyway.
+	   */
+	  || target == GL_ARRAY_BUFFER || target == GL_ELEMENT_ARRAY_BUFFER
+#endif
+	 )
+      {
 	 intel_obj->sys_buffer = malloc(size);
 	 if (intel_obj->sys_buffer != NULL) {
 	    if (data != NULL)
@@ -174,7 +178,6 @@ intel_bufferobj_data(struct gl_context * ctx,
 	    return GL_TRUE;
 	 }
       }
-#endif
       intel_bufferobj_alloc_buffer(intel, intel_obj);
       if (!intel_obj->buffer)
          return GL_FALSE;
@@ -211,9 +214,13 @@ intel_bufferobj_subdata(struct gl_context * ctx,
    if (intel_obj->region)
       intel_bufferobj_cow(intel, intel_obj);
 
-   if (intel_obj->sys_buffer)
+   if (intel_obj->sys_buffer) {
+      if (intel_obj->buffer) {
+	 drm_intel_bo_unreference(intel_obj->buffer);
+	 intel_obj->buffer = NULL;
+      }
       memcpy((char *)intel_obj->sys_buffer + offset, data, size);
-   else {
+   } else {
       /* Flush any existing batchbuffer that might reference this data. */
       if (intel->gen < 6) {
 	 if (drm_intel_bo_busy(intel_obj->buffer) ||
@@ -280,6 +287,10 @@ intel_bufferobj_map(struct gl_context * ctx,
    assert(intel_obj);
 
    if (intel_obj->sys_buffer) {
+      if (!read_only && intel_obj->buffer) {
+	 drm_intel_bo_unreference(intel_obj->buffer);
+	 intel_obj->buffer = NULL;
+      }
       obj->Pointer = intel_obj->sys_buffer;
       obj->Length = obj->Size;
       obj->Offset = 0;
@@ -347,6 +358,10 @@ intel_bufferobj_map_range(struct gl_context * ctx,
    obj->AccessFlags = access;
 
    if (intel_obj->sys_buffer) {
+      if (access != GL_READ_ONLY_ARB && intel_obj->buffer) {
+	 drm_intel_bo_unreference(intel_obj->buffer);
+	 intel_obj->buffer = NULL;
+      }
       obj->Pointer = intel_obj->sys_buffer + offset;
       return obj->Pointer;
    }
@@ -525,20 +540,16 @@ intel_bufferobj_buffer(struct intel_context *intel,
    }
 
    if (intel_obj->buffer == NULL) {
-      void *sys_buffer = intel_obj->sys_buffer;
-
-      /* only one of buffer and sys_buffer could be non-NULL */
+      /* XXX suballocate for DYNAMIC READ */
       intel_bufferobj_alloc_buffer(intel, intel_obj);
-      intel_obj->sys_buffer = NULL;
-
-      intel_bufferobj_subdata(&intel->ctx,
-			      GL_ARRAY_BUFFER_ARB,
-			      0,
-			      intel_obj->Base.Size,
-			      sys_buffer,
-			      &intel_obj->Base);
-      free(sys_buffer);
-      intel_obj->sys_buffer = NULL;
+      drm_intel_bo_subdata(intel_obj->buffer,
+			   0, intel_obj->Base.Size,
+			   intel_obj->sys_buffer);
+
+      if (flag != INTEL_READ) {
+	 free(intel_obj->sys_buffer);
+	 intel_obj->sys_buffer = NULL;
+      }
    }
 
    return intel_obj->buffer;