exa: reintroduce src rect optimisation, with a slightly higher threshold.

- I got some feedback on gtkperf line test regression.
- The increased threshold should ensure the destination optimisation is dominant.

1 files changed, 7 insertions, 0 deletions

diff --git a/exa/exa_migration.c b/exa/exa_migration.c
index 59db25b72..9d0eda0de 100644
--- a/exa/exa_migration.c
+++ b/exa/exa_migration.c
@@ -257,6 +257,13 @@ exaCopyDirty(ExaMigrationPtr migrate, RegionPtr pValidDst, RegionPtr pValidSrc,
     pExaPixmap->offscreen = save_offscreen;
     pPixmap->devKind = save_pitch;
 
+    /* Try to prevent source valid region from growing too many rects by
+     * removing parts of it which are also in the destination valid region.
+     * Removing anything beyond that would lead to data loss.
+     */
+    if (REGION_NUM_RECTS(pValidSrc) > 20)
+	REGION_SUBTRACT(pScreen, pValidSrc, pValidSrc, pValidDst);
+
     /* The copied bits are now valid in destination */
     REGION_UNION(pScreen, pValidDst, pValidDst, &CopyReg);