xorg-server-1.4/hw/dmx/dmxsync.c

   1 /*
   2  * Copyright 2002-2004 Red Hat Inc., Durham, North Carolina.
   3  *
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining
   7  * a copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation on the rights to use, copy, modify, merge,
  10  * publish, distribute, sublicense, and/or sell copies of the Software,
  11  * and to permit persons to whom the Software is furnished to do so,
  12  * subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial
  16  * portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21  * NON-INFRINGEMENT.  IN NO EVENT SHALL RED HAT AND/OR THEIR SUPPLIERS
  22  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  23  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  24  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  25  * SOFTWARE.
  26  */
  27
  28 /*
  29  * Authors:
  30  *   Rickard E. (Rik) Faith <faith@redhat.com>
  31  *
  32  */
  33
  34 /** \file
  35  *
  36  * The DMX server code is written to call #dmxSync() whenever an XSync()
  37  * might be necessary.  However, since XSync() requires a two way
  38  * communication with the other X server, eliminating unnecessary
  39  * XSync() calls is a key performance optimization.  Support for this
  40  * optimization is provided here.  Statistics about XSync() calls and
  41  * latency are gathered in #dmxstat.c.
  42  *
  43  * During the initial conversion from calling XSync() immediately to the
  44  * XSync() batching method implemented in this file, it was noted that,
  45  * out of more than 300 \a x11perf tests, 8 tests became more than 100
  46  * times faster, with 68 more than 50X faster, 114 more than 10X faster,
  47  * and 181 more than 2X faster. */
  48
  49 #ifdef HAVE_DMX_CONFIG_H
  50 #include <dmx-config.h>
  51 #endif
  52
  53 #include "dmx.h"
  54 #include "dmxsync.h"
  55 #include "dmxstat.h"
  56 #include "dmxlog.h"
  57 #include <sys/time.h>
  58
  59 static int        dmxSyncInterval = 100; /* Default interval in milliseconds */
  60 static OsTimerPtr dmxSyncTimer;
  61 static int        dmxSyncPending;
  62
  63 static void dmxDoSync(DMXScreenInfo *dmxScreen)
  64 {
  65     dmxScreen->needsSync = FALSE;
  66
  67     if (!dmxScreen->beDisplay)
  68         return; /* FIXME: Is this correct behavior for sync stats? */
  69
  70     if (!dmxStatInterval) {
  71         XSync(dmxScreen->beDisplay, False);
  72     } else {
  73         struct timeval start, stop;
  74
  75         gettimeofday(&start, 0);
  76         XSync(dmxScreen->beDisplay, False);
  77         gettimeofday(&stop, 0);
  78         dmxStatSync(dmxScreen, &stop, &start, dmxSyncPending);
  79     }
  80 }
  81
  82 static CARD32 dmxSyncCallback(OsTimerPtr timer, CARD32 time, pointer arg)
  83 {
  84     int           i;
  85
  86     if (dmxSyncPending) {
  87         for (i = 0; i < dmxNumScreens; i++) {
  88             DMXScreenInfo *dmxScreen = &dmxScreens[i];
  89             if (dmxScreen->needsSync) dmxDoSync(dmxScreen);
  90         }
  91     }
  92     dmxSyncPending = 0;
  93     return 0;                   /* Do not place on queue again */
  94 }
  95
  96 static void dmxSyncBlockHandler(pointer blockData, OSTimePtr pTimeout,
  97                                 pointer pReadMask)
  98 {
  99     TimerForce(dmxSyncTimer);
 100 }
 101
 102 static void dmxSyncWakeupHandler(pointer blockData, int result,
 103                                  pointer pReadMask)
 104 {
 105 }
 106
 107 /** Request the XSync() batching optimization with the specified \a
 108  * interval (in mS).  If the \a interval is 0, 100mS is used.  If the \a
 109  * interval is less than 0, then the XSync() batching optimization is
 110  * not requested (e.g., so the -syncbatch -1 command line option can
 111  * turn off the default 100mS XSync() batching).
 112  *
 113  * Note that the parameter to this routine is a string, since it will
 114  * usually be called from #ddxProcessArgument in #dmxinit.c */
 115 void dmxSyncActivate(const char *interval)
 116 {
 117     dmxSyncInterval = (interval ? atoi(interval) : 100);
 118
 119     if (dmxSyncInterval < 0) dmxSyncInterval = 0;
 120 }
 121
 122 /** Initialize the XSync() batching optimization, but only if
 123  * #dmxSyncActivate was last called with a non-negative value. */
 124 void dmxSyncInit(void)
 125 {
 126     if (dmxSyncInterval) {
 127         RegisterBlockAndWakeupHandlers(dmxSyncBlockHandler,
 128                                        dmxSyncWakeupHandler,
 129                                        NULL);
 130         dmxLog(dmxInfo, "XSync batching with %d ms interval\n",
 131                dmxSyncInterval);
 132     } else {
 133         dmxLog(dmxInfo, "XSync batching disabled\n");
 134     }
 135 }
 136
 137 /** Request an XSync() to the display used by \a dmxScreen.  If \a now
 138  * is TRUE, call XSync() immediately instead of waiting for the next
 139  * XSync() batching point.  Note that if XSync() batching was deselected
 140  * with #dmxSyncActivate() before #dmxSyncInit() was called, then no
 141  * XSync() batching is performed and this function always calles XSync()
 142  * immediately.
 143  *
 144  * (Note that this function uses TimerSet but works correctly in the
 145  * face of a server generation.  See the source for details.)
 146  *
 147  * If \a dmxScreen is \a NULL, then all pending syncs will be flushed
 148  * immediately.
 149  */
 150 void dmxSync(DMXScreenInfo *dmxScreen, Bool now)
 151 {
 152     static unsigned long dmxGeneration = 0;
 153
 154     if (dmxSyncInterval) {
 155         if (dmxGeneration != serverGeneration) {
 156             /* Server generation does a TimerInit, which frees all
 157              * timers.  So, at this point dmxSyncTimer is either:
 158              * 1) NULL, iff dmxGeneration == 0,
 159              * 2) freed, if it was on a queue (dmxSyncPending != 0), or
 160              * 3) allocated, if it wasn't on a queue (dmxSyncPending == 0)
 161              */
 162             if (dmxSyncTimer && !dmxSyncPending) xfree(dmxSyncTimer);
 163             dmxSyncTimer  = NULL;
 164             now           = TRUE;
 165             dmxGeneration = serverGeneration;
 166         }
 167                                 /* Queue sync */
 168         if (dmxScreen) {
 169             dmxScreen->needsSync = TRUE;
 170             ++dmxSyncPending;
 171         }
 172
 173                                 /* Do sync or set time for later */
 174         if (now || !dmxScreen) {
 175             if (!TimerForce(dmxSyncTimer)) dmxSyncCallback(NULL, 0, NULL);
 176             /* At this point, dmxSyncPending == 0 because
 177              * dmxSyncCallback must have been called. */
 178             if (dmxSyncPending)
 179                 dmxLog(dmxFatal, "dmxSync(%s,%d): dmxSyncPending = %d\n",
 180                        dmxScreen ? dmxScreen->name : "", now, dmxSyncPending);
 181         } else {
 182             dmxScreen->needsSync = TRUE;
 183             if (dmxSyncPending == 1)
 184                 dmxSyncTimer = TimerSet(dmxSyncTimer, 0, dmxSyncInterval,
 185                                         dmxSyncCallback, NULL);
 186         }
 187     } else {
 188                                 /* If dmxSyncInterval is not being used,
 189                                  * then all the backends are already
 190                                  * up-to-date. */
 191         if (dmxScreen) dmxDoSync(dmxScreen);
 192     }
 193 }