sna: Map the upload buffer using an LLC bo

In order to avoid having to perform a copy of the cacheable buffer into
GPU space, we can map a bo as cacheable and write directly to its
contents. This is only a win on systems that can avoid the clflush, and
also we have to go to greater measures to avoid unnecessary
serialisation upon that CPU bo. Sadly, we do not yet go to enough length
to avoid negatively impacting ShmPutImage, but that does not appear to
be a artefact of stalling upon a CPU buffer.

Note, LLC is a SandyBridge feature enabled by default in kernel 3.1 and
later. In time, we should be able to expose similar support for
snoopable buffers for other generations.

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

1 files changed, 24 insertions, 20 deletions

diff --git a/src/sna/sna_trapezoids.c b/src/sna/sna_trapezoids.c
index 27987d87..287f8833 100644
--- a/src/sna/sna_trapezoids.c
+++ b/src/sna/sna_trapezoids.c
@@ -3176,7 +3176,8 @@ trapezoid_span_inplace(CARD8 op, PicturePtr src, PicturePtr dst,
 	}
 
 	region.data = NULL;
-	if (!sna_drawable_move_region_to_cpu(dst->pDrawable, &region, true))
+	if (!sna_drawable_move_region_to_cpu(dst->pDrawable, &region,
+					     MOVE_READ | MOVE_WRITE))
 		return true;
 
 	pixmap = get_drawable_pixmap(dst->pDrawable);
@@ -3313,16 +3314,20 @@ trapezoid_span_fallback(CARD8 op, PicturePtr src, PicturePtr dst,
 		region.extents.y2 = dst_y + extents.y2;
 		region.data = NULL;
 
-		if (!sna_drawable_move_region_to_cpu(dst->pDrawable, &region, true))
+		if (!sna_drawable_move_region_to_cpu(dst->pDrawable, &region,
+						     MOVE_READ | MOVE_WRITE))
 			goto done;
 		if (dst->alphaMap  &&
-		    !sna_drawable_move_to_cpu(dst->alphaMap->pDrawable, true))
+		    !sna_drawable_move_to_cpu(dst->alphaMap->pDrawable,
+					      MOVE_READ | MOVE_WRITE))
 			goto done;
 		if (src->pDrawable) {
-			if (!sna_drawable_move_to_cpu(src->pDrawable, false))
+			if (!sna_drawable_move_to_cpu(src->pDrawable,
+						      MOVE_READ))
 				goto done;
 			if (src->alphaMap &&
-			    !sna_drawable_move_to_cpu(src->alphaMap->pDrawable, false))
+			    !sna_drawable_move_to_cpu(src->alphaMap->pDrawable,
+						      MOVE_READ))
 				goto done;
 		}
 
@@ -3661,20 +3666,18 @@ skip:
 static void mark_damaged(PixmapPtr pixmap, struct sna_pixmap *priv,
 			 BoxPtr box, int16_t x, int16_t y)
 {
-	if (!priv->gpu_only) {
-		box->x1 += x; box->x2 += x;
-		box->y1 += y; box->y2 += y;
-		if (box->x1 <= 0 && box->y1 <= 0 &&
-		    box->x2 >= pixmap->drawable.width &&
-		    box->y2 >= pixmap->drawable.height) {
-			sna_damage_destroy(&priv->cpu_damage);
-			sna_damage_all(&priv->gpu_damage,
-				       pixmap->drawable.width,
-				       pixmap->drawable.height);
-		} else {
-			sna_damage_add_box(&priv->gpu_damage, box);
-			sna_damage_subtract_box(&priv->cpu_damage, box);
-		}
+	box->x1 += x; box->x2 += x;
+	box->y1 += y; box->y2 += y;
+	if (box->x1 <= 0 && box->y1 <= 0 &&
+	    box->x2 >= pixmap->drawable.width &&
+	    box->y2 >= pixmap->drawable.height) {
+		sna_damage_destroy(&priv->cpu_damage);
+		sna_damage_all(&priv->gpu_damage,
+			       pixmap->drawable.width,
+			       pixmap->drawable.height);
+	} else {
+		sna_damage_add_box(&priv->gpu_damage, box);
+		sna_damage_subtract_box(&priv->cpu_damage, box);
 	}
 }
 
@@ -3887,7 +3890,8 @@ sna_add_traps(PicturePtr picture, INT16 x, INT16 y, int n, xTrap *t)
 	}
 
 	DBG(("%s -- fallback\n", __FUNCTION__));
-	if (sna_drawable_move_to_cpu(picture->pDrawable, true))
+	if (sna_drawable_move_to_cpu(picture->pDrawable,
+				     MOVE_READ | MOVE_WRITE))
 		fbAddTraps(picture, x, y, n, t);
 }