Add a new migration scheme, "always", which will move pixmaps to their

    desired location always (unless they don't fit in FB, in which case
    they all get moved out for software rendering). The default remains as
    before, but can be controlled by the MigrationHeuristic xorg.conf
    option (which is intentionally not documented, as it may be
    short-lived). This is part of the exa-damagetrack work, which appears
    stable in testing with fakexa, unlike the work as a whole.

1 files changed, 66 insertions, 27 deletions

diff --git a/exa/exa_migration.c b/exa/exa_migration.c
index d48abf066..ce4ce7455 100644
--- a/exa/exa_migration.c
+++ b/exa/exa_migration.c
@@ -247,6 +247,10 @@ exaMoveOutPixmap (PixmapPtr pPixmap)
     }
 }
 
+/**
+ * For the "greedy" migration scheme, pushes the pixmap toward being located in
+ * framebuffer memory.
+ */
 static void
 exaMigrateTowardFb (PixmapPtr pPixmap)
 {
@@ -285,6 +289,10 @@ exaMigrateTowardFb (PixmapPtr pPixmap)
     ExaOffscreenMarkUsed (pPixmap);
 }
 
+/**
+ * For the "greedy" migration scheme, pushes the pixmap toward being located in
+ * system memory.
+ */
 static void
 exaMigrateTowardSys (PixmapPtr pPixmap)
 {
@@ -314,13 +322,14 @@ exaMigrateTowardSys (PixmapPtr pPixmap)
 
 /**
  * Performs migration of the pixmaps according to the operation information
- * provided in pixmaps and can_accel.  In the future, other migration schemes
- * may be added, which is facilitated by having this logic all in one place.
+ * provided in pixmaps and can_accel and the migration scheme chosen in the
+ * config file.
  */
 void
 exaDoMigration (ExaMigrationPtr pixmaps, int npixmaps, Bool can_accel)
 {
     ScreenPtr pScreen = pixmaps[0].pPix->drawable.pScreen;
+    ExaScreenPriv(pScreen);
     int i, j;
 
     /* If anything is pinned in system memory, we won't be able to
@@ -338,33 +347,63 @@ exaDoMigration (ExaMigrationPtr pixmaps, int npixmaps, Bool can_accel)
 	}
     }
 
-    /* If we can't accelerate, either because the driver can't or because one of
-     * the pixmaps is pinned in system memory, then we migrate everybody toward
-     * system memory.
-     *
-     * We also migrate toward system if all pixmaps involved are currently in
-     * system memory -- this can mitigate thrashing when there are significantly
-     * more pixmaps active than would fit in memory.
-     *
-     * If not, then we migrate toward FB so that hopefully acceleration can
-     * happen.
-     */
-    if (!can_accel) {
-	for (i = 0; i < npixmaps; i++)
-	    exaMigrateTowardSys (pixmaps[i].pPix);
-	return;
-    }
+    if (pExaScr->migration == ExaMigrationGreedy) {
+	/* If we can't accelerate, either because the driver can't or because one of
+	 * the pixmaps is pinned in system memory, then we migrate everybody toward
+	 * system memory.
+	 *
+	 * We also migrate toward system if all pixmaps involved are currently in
+	 * system memory -- this can mitigate thrashing when there are significantly
+	 * more pixmaps active than would fit in memory.
+	 *
+	 * If not, then we migrate toward FB so that hopefully acceleration can
+	 * happen.
+	 */
+	if (!can_accel) {
+	    for (i = 0; i < npixmaps; i++)
+		exaMigrateTowardSys (pixmaps[i].pPix);
+	    return;
+	}
 
-    for (i = 0; i < npixmaps; i++) {
-	if (exaPixmapIsOffscreen(pixmaps[i].pPix)) {
-	    /* Found one in FB, so move all to FB. */
-	    for (j = 0; j < npixmaps; j++)
-		exaMigrateTowardFb(pixmaps[j].pPix);
+	for (i = 0; i < npixmaps; i++) {
+	    if (exaPixmapIsOffscreen(pixmaps[i].pPix)) {
+		/* Found one in FB, so move all to FB. */
+		for (j = 0; j < npixmaps; j++)
+		    exaMigrateTowardFb(pixmaps[j].pPix);
+		return;
+	    }
+	}
+
+	/* Nobody's in FB, so move all away from FB. */
+	for (i = 0; i < npixmaps; i++)
+	    exaMigrateTowardSys(pixmaps[i].pPix);
+    } else if (pExaScr->migration == ExaMigrationAlways) {
+	/* Always move the pixmaps out if we can't accelerate.  If we can
+	 * accelerate, try to move them all in.  If that fails, then move them
+	 * back out.
+	 */
+	if (!can_accel) {
+	    for (i = 0; i < npixmaps; i++)
+		exaMoveOutPixmap(pixmaps[i].pPix);
 	    return;
 	}
-    }
 
-    /* Nobody's in FB, so move all away from FB. */
-    for (i = 0; i < npixmaps; i++)
-	exaMigrateTowardSys(pixmaps[i].pPix);
+	/* Now, try to move them all into FB */
+	for (i = 0; i < npixmaps; i++) {
+	    exaMoveInPixmap(pixmaps[i].pPix);
+	    ExaOffscreenMarkUsed (pixmaps[i].pPix);
+	}
+
+	/* If we couldn't fit everything in, then kick back out */
+	for (i = 0; i < npixmaps; i++) {
+	    if (!exaPixmapIsOffscreen(pixmaps[i].pPix)) {
+		EXA_FALLBACK(("Pixmap %p (%dx%d) not in fb\n", pixmaps[i].pPix,
+			      pixmaps[i].pPix->drawable.width,
+			      pixmaps[i].pPix->drawable.height));
+		for (j = 0; j < npixmaps; j++)
+		    exaMoveOutPixmap(pixmaps[j].pPix);
+		break;
+	    }
+	}
+    }
 }