sna: Only use the cpu bo for xfer between CPU and GPU if either is busy

The synchronisation costs overwhelm any benefit from offloading the
copy, unless we are currently streaming the updates anyway.

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

1 files changed, 21 insertions, 20 deletions

diff --git a/src/sna/sna_accel.c b/src/sna/sna_accel.c
index dc330ca8..d5420a33 100644
--- a/src/sna/sna_accel.c
+++ b/src/sna/sna_accel.c
@@ -857,6 +857,14 @@ sna_pixmap_create_mappable_gpu(PixmapPtr pixmap)
 	return priv->gpu_bo && kgem_bo_is_mappable(&sna->kgem, priv->gpu_bo);
 }
 
+static bool use_cpu_bo_for_xfer(struct sna_pixmap *priv)
+{
+	if (priv->cpu_bo == NULL)
+		return FALSE;
+
+	return kgem_bo_is_busy(priv->gpu_bo) || kgem_bo_is_busy(priv->cpu_bo);
+}
+
 bool
 _sna_pixmap_move_to_cpu(PixmapPtr pixmap, unsigned int flags)
 {
@@ -1028,16 +1036,12 @@ skip_inplace_map:
 
 		n = sna_damage_get_boxes(priv->gpu_damage, &box);
 		if (n) {
-			struct kgem_bo *dst_bo;
 			Bool ok = FALSE;
 
-			dst_bo = NULL;
-			if (sna->kgem.gen >= 30)
-				dst_bo = priv->cpu_bo;
-			if (dst_bo)
+			if (sna->kgem.gen >= 30 && use_cpu_bo_for_xfer(priv))
 				ok = sna->render.copy_boxes(sna, GXcopy,
 							    pixmap, priv->gpu_bo, 0, 0,
-							    pixmap, dst_bo, 0, 0,
+							    pixmap, priv->cpu_bo, 0, 0,
 							    box, n);
 			if (!ok)
 				sna_read_boxes(sna,
@@ -1421,7 +1425,7 @@ sna_drawable_move_region_to_cpu(DrawablePtr drawable,
 			assert(pixmap_contains_damage(pixmap, priv->gpu_damage));
 
 			ok = FALSE;
-			if (priv->cpu_bo && sna->kgem.gen >= 30)
+			if (sna->kgem.gen >= 30 && use_cpu_bo_for_xfer(priv))
 				ok = sna->render.copy_boxes(sna, GXcopy,
 							    pixmap, priv->gpu_bo, 0, 0,
 							    pixmap, priv->cpu_bo, 0, 0,
@@ -1496,7 +1500,7 @@ sna_drawable_move_region_to_cpu(DrawablePtr drawable,
 				if (n) {
 					Bool ok = FALSE;
 
-					if (priv->cpu_bo && sna->kgem.gen >= 30)
+					if (sna->kgem.gen >= 30 && use_cpu_bo_for_xfer(priv))
 						ok = sna->render.copy_boxes(sna, GXcopy,
 									    pixmap, priv->gpu_bo, 0, 0,
 									    pixmap, priv->cpu_bo, 0, 0,
@@ -1516,10 +1520,9 @@ sna_drawable_move_region_to_cpu(DrawablePtr drawable,
 								      &r->extents)) {
 				BoxPtr box = REGION_RECTS(r);
 				int n = REGION_NUM_RECTS(r);
-				Bool ok;
+				Bool ok = FALSE;
 
-				ok = FALSE;
-				if (priv->cpu_bo && sna->kgem.gen >= 30)
+				if (sna->kgem.gen >= 30 && use_cpu_bo_for_xfer(priv))
 					ok = sna->render.copy_boxes(sna, GXcopy,
 								    pixmap, priv->gpu_bo, 0, 0,
 								    pixmap, priv->cpu_bo, 0, 0,
@@ -1539,10 +1542,9 @@ sna_drawable_move_region_to_cpu(DrawablePtr drawable,
 				if (sna_damage_intersect(priv->gpu_damage, r, &need)) {
 					BoxPtr box = REGION_RECTS(&need);
 					int n = REGION_NUM_RECTS(&need);
-					Bool ok;
+					Bool ok = FALSE;
 
-					ok = FALSE;
-					if (priv->cpu_bo && sna->kgem.gen >= 30)
+					if (sna->kgem.gen >= 30 && use_cpu_bo_for_xfer(priv))
 						ok = sna->render.copy_boxes(sna, GXcopy,
 									    pixmap, priv->gpu_bo, 0, 0,
 									    pixmap, priv->cpu_bo, 0, 0,
@@ -1732,10 +1734,9 @@ sna_pixmap_move_area_to_gpu(PixmapPtr pixmap, BoxPtr box, unsigned int flags)
 
 		n = sna_damage_get_boxes(priv->cpu_damage, &box);
 		if (n) {
-			Bool ok;
+			Bool ok = FALSE;
 
-			ok = FALSE;
-			if (priv->cpu_bo)
+			if (use_cpu_bo_for_xfer(priv))
 				ok = sna->render.copy_boxes(sna, GXcopy,
 							    pixmap, priv->cpu_bo, 0, 0,
 							    pixmap, priv->gpu_bo, 0, 0,
@@ -1768,7 +1769,7 @@ sna_pixmap_move_area_to_gpu(PixmapPtr pixmap, BoxPtr box, unsigned int flags)
 	} else if (DAMAGE_IS_ALL(priv->cpu_damage) ||
 		   sna_damage_contains_box__no_reduce(priv->cpu_damage, box)) {
 		Bool ok = FALSE;
-		if (priv->cpu_bo)
+		if (use_cpu_bo_for_xfer(priv))
 			ok = sna->render.copy_boxes(sna, GXcopy,
 						    pixmap, priv->cpu_bo, 0, 0,
 						    pixmap, priv->gpu_bo, 0, 0,
@@ -1791,7 +1792,7 @@ sna_pixmap_move_area_to_gpu(PixmapPtr pixmap, BoxPtr box, unsigned int flags)
 
 		box = REGION_RECTS(&i);
 		ok = FALSE;
-		if (priv->cpu_bo)
+		if (use_cpu_bo_for_xfer(priv))
 			ok = sna->render.copy_boxes(sna, GXcopy,
 						    pixmap, priv->cpu_bo, 0, 0,
 						    pixmap, priv->gpu_bo, 0, 0,
@@ -2250,7 +2251,7 @@ sna_pixmap_move_to_gpu(PixmapPtr pixmap, unsigned flags)
 		DBG(("%s: uploading %d damage boxes\n", __FUNCTION__, n));
 
 		ok = FALSE;
-		if (priv->cpu_bo)
+		if (use_cpu_bo_for_xfer(priv))
 			ok = sna->render.copy_boxes(sna, GXcopy,
 						    pixmap, priv->cpu_bo, 0, 0,
 						    pixmap, priv->gpu_bo, 0, 0,