1 files changed, 193 insertions, 0 deletions
diff --git a/xorg-server/hw/dmx/dmxsync.c b/xorg-server/hw/dmx/dmxsync.c
new file mode 100644
index 000000000..c1aa43107
--- /dev/null
+++ b/xorg-server/hw/dmx/dmxsync.c
@@ -0,0 +1,193 @@
+/*
+ * Copyright 2002-2004 Red Hat Inc., Durham, North Carolina.
+ *
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation on the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NON-INFRINGEMENT.  IN NO EVENT SHALL RED HAT AND/OR THEIR SUPPLIERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/*
+ * Authors:
+ *   Rickard E. (Rik) Faith <faith@redhat.com>
+ *
+ */
+
+/** \file
+ *
+ * The DMX server code is written to call #dmxSync() whenever an XSync()
+ * might be necessary.  However, since XSync() requires a two way
+ * communication with the other X server, eliminating unnecessary
+ * XSync() calls is a key performance optimization.  Support for this
+ * optimization is provided here.  Statistics about XSync() calls and
+ * latency are gathered in #dmxstat.c.
+ *
+ * During the initial conversion from calling XSync() immediately to the
+ * XSync() batching method implemented in this file, it was noted that,
+ * out of more than 300 \a x11perf tests, 8 tests became more than 100
+ * times faster, with 68 more than 50X faster, 114 more than 10X faster,
+ * and 181 more than 2X faster. */
+
+#ifdef HAVE_DMX_CONFIG_H
+#include <dmx-config.h>
+#endif
+
+#include "dmx.h"
+#include "dmxsync.h"
+#include "dmxstat.h"
+#include "dmxlog.h"
+#include <sys/time.h>
+
+static int        dmxSyncInterval = 100; /* Default interval in milliseconds */
+static OsTimerPtr dmxSyncTimer;
+static int        dmxSyncPending;
+
+static void dmxDoSync(DMXScreenInfo *dmxScreen)
+{
+    dmxScreen->needsSync = FALSE;
+
+    if (!dmxScreen->beDisplay)
+	return; /* FIXME: Is this correct behavior for sync stats? */
+
+    if (!dmxStatInterval) {
+        XSync(dmxScreen->beDisplay, False);
+    } else {
+        struct timeval start, stop;
+        
+        gettimeofday(&start, 0);
+        XSync(dmxScreen->beDisplay, False);
+        gettimeofday(&stop, 0);
+        dmxStatSync(dmxScreen, &stop, &start, dmxSyncPending);
+    }
+}
+
+static CARD32 dmxSyncCallback(OsTimerPtr timer, CARD32 time, pointer arg)
+{
+    int           i;
+
+    if (dmxSyncPending) {
+        for (i = 0; i < dmxNumScreens; i++) {
+            DMXScreenInfo *dmxScreen = &dmxScreens[i];
+            if (dmxScreen->needsSync) dmxDoSync(dmxScreen);
+        }
+    }
+    dmxSyncPending = 0;
+    return 0;                   /* Do not place on queue again */
+}
+
+static void dmxSyncBlockHandler(pointer blockData, OSTimePtr pTimeout,
+                                pointer pReadMask)
+{
+    TimerForce(dmxSyncTimer);
+}
+
+static void dmxSyncWakeupHandler(pointer blockData, int result,
+                                 pointer pReadMask)
+{
+}
+
+/** Request the XSync() batching optimization with the specified \a
+ * interval (in mS).  If the \a interval is 0, 100mS is used.  If the \a
+ * interval is less than 0, then the XSync() batching optimization is
+ * not requested (e.g., so the -syncbatch -1 command line option can
+ * turn off the default 100mS XSync() batching).
+ *
+ * Note that the parameter to this routine is a string, since it will
+ * usually be called from #ddxProcessArgument in #dmxinit.c */
+void dmxSyncActivate(const char *interval)
+{
+    dmxSyncInterval = (interval ? atoi(interval) : 100);
+
+    if (dmxSyncInterval < 0) dmxSyncInterval = 0;
+}
+
+/** Initialize the XSync() batching optimization, but only if
+ * #dmxSyncActivate was last called with a non-negative value. */
+void dmxSyncInit(void)
+{
+    if (dmxSyncInterval) {
+        RegisterBlockAndWakeupHandlers(dmxSyncBlockHandler,
+                                       dmxSyncWakeupHandler,
+                                       NULL);
+        dmxLog(dmxInfo, "XSync batching with %d ms interval\n",
+               dmxSyncInterval);
+    } else {
+        dmxLog(dmxInfo, "XSync batching disabled\n");
+    }
+}
+
+/** Request an XSync() to the display used by \a dmxScreen.  If \a now
+ * is TRUE, call XSync() immediately instead of waiting for the next
+ * XSync() batching point.  Note that if XSync() batching was deselected
+ * with #dmxSyncActivate() before #dmxSyncInit() was called, then no
+ * XSync() batching is performed and this function always calles XSync()
+ * immediately.
+ *
+ * (Note that this function uses TimerSet but works correctly in the
+ * face of a server generation.  See the source for details.)
+ *
+ * If \a dmxScreen is \a NULL, then all pending syncs will be flushed
+ * immediately.
+ */
+void dmxSync(DMXScreenInfo *dmxScreen, Bool now)
+{
+    static unsigned long dmxGeneration = 0;
+
+    if (dmxSyncInterval) {
+        if (dmxGeneration != serverGeneration) {
+            /* Server generation does a TimerInit, which frees all
+             * timers.  So, at this point dmxSyncTimer is either:
+             * 1) NULL, iff dmxGeneration == 0,
+             * 2) freed, if it was on a queue (dmxSyncPending != 0), or
+             * 3) allocated, if it wasn't on a queue (dmxSyncPending == 0)
+             */
+            if (dmxSyncTimer && !dmxSyncPending) xfree(dmxSyncTimer);
+            dmxSyncTimer  = NULL;
+            now           = TRUE;
+            dmxGeneration = serverGeneration;
+        }
+                                /* Queue sync */
+        if (dmxScreen) {
+            dmxScreen->needsSync = TRUE;
+            ++dmxSyncPending;
+        }
+
+                                /* Do sync or set time for later */
+        if (now || !dmxScreen) {
+            if (!TimerForce(dmxSyncTimer)) dmxSyncCallback(NULL, 0, NULL);
+            /* At this point, dmxSyncPending == 0 because
+             * dmxSyncCallback must have been called. */
+            if (dmxSyncPending)
+                dmxLog(dmxFatal, "dmxSync(%s,%d): dmxSyncPending = %d\n",
+                       dmxScreen ? dmxScreen->name : "", now, dmxSyncPending);
+        } else {
+            dmxScreen->needsSync = TRUE;
+            if (dmxSyncPending == 1)
+                dmxSyncTimer = TimerSet(dmxSyncTimer, 0, dmxSyncInterval,
+                                        dmxSyncCallback, NULL);
+        }
+    } else {
+                                /* If dmxSyncInterval is not being used,
+                                 * then all the backends are already
+                                 * up-to-date. */
+        if (dmxScreen) dmxDoSync(dmxScreen);
+    }
+}