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* Copyright 2002, 2003 Red Hat Inc., Durham, North Carolina.
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation on the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial
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* portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NON-INFRINGEMENT. IN NO EVENT SHALL RED HAT AND/OR THEIR SUPPLIERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* Rickard E. (Rik) Faith <faith@redhat.com>
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* The DMX server code is written to call #dmxSync() whenever an XSync()
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* might be necessary. However, since XSync() requires a two way
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* communication with the other X server, eliminating unnecessary
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* XSync() calls is a key performance optimization. Support for this
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* optimization is provided in #dmxsync.c. This file provides routines
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* that evaluate this optimization by counting the number of XSync()
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* calls and monitoring their latency. This functionality can be turned
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* on using the -stat command-line parameter. */
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#ifdef HAVE_DMX_CONFIG_H
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#include <dmx-config.h>
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#include <X11/Xos.h> /* For sys/time.h */
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/** Used to compute a running average of value. */
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typedef struct _DMXStatAvg {
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unsigned long value[DMX_STAT_LENGTH];
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/** Statistical information about XSync calls. */
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unsigned long syncCount;
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unsigned long oldSyncCount;
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unsigned long bins[DMX_STAT_BINS];
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/* Interval in mS between statistic message log entries. */
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static int dmxStatDisplays;
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static OsTimerPtr dmxStatTimer;
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/** Return the number of microseconds as an unsigned long.
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* Unfortunately, this is only useful for intervals < about 4 sec. */
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static unsigned long usec(struct timeval *stop, struct timeval *start)
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return (stop->tv_sec - start->tv_sec) * 1000000
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+ stop->tv_usec - start->tv_usec;
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static unsigned long avg(DMXStatAvg *data, unsigned long *max)
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if (!data->count) return 0;
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for (i = 0, sum = 0; i < data->count; i++) {
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if (data->value[i] > *max) *max = data->value[i];
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sum += data->value[i];
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return sum / data->count;
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/** Turn on XSync statistic gathering and printing. Print every \a
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* interval seconds, with lines for the first \a displays. If \a
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* interval is NULL, 1 will be used. If \a displays is NULL, 0 will be
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* used (meaning a line for every display will be printed). Note that
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* this function takes string arguments because it will usually be
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* called from #ddxProcessArgument in #dmxinit.c. */
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void dmxStatActivate(const char *interval, const char *displays)
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dmxStatInterval = (interval ? atoi(interval) : 1) * 1000;
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dmxStatDisplays = (displays ? atoi(displays) : 0);
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if (dmxStatInterval < 1000) dmxStatInterval = 1000;
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if (dmxStatDisplays < 0) dmxStatDisplays = 0;
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/** Allocate a \a DMXStatInfo structure. */
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DMXStatInfo *dmxStatAlloc(void)
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DMXStatInfo *pt = malloc(sizeof(*pt));
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memset(pt, 0, sizeof(*pt));
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/** Free the memory used by a \a DMXStatInfo structure. */
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void dmxStatFree(DMXStatInfo *pt)
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static void dmxStatValue(DMXStatAvg *data, unsigned long value)
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if (data->count != DMX_STAT_LENGTH) ++data->count;
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if (data->pos >= DMX_STAT_LENGTH-1) data->pos = 0;
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data->value[data->pos++] = value;
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/** Note that a XSync() was just done on \a dmxScreen with the \a start
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* and \a stop times (from gettimeofday()) and the number of
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* pending-but-not-yet-processed XSync requests. This routine is called
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* from #dmxDoSync in #dmxsync.c */
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void dmxStatSync(DMXScreenInfo *dmxScreen,
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struct timeval *stop, struct timeval *start,
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unsigned long pending)
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DMXStatInfo *s = dmxScreen->stat;
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unsigned long elapsed = usec(stop, start);
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unsigned long thresh;
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dmxStatValue(&s->usec, elapsed);
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dmxStatValue(&s->pending, pending);
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for (i = 0, thresh = DMX_STAT_BIN0; i < DMX_STAT_BINS-1; i++) {
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if (elapsed < thresh) {
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thresh *= DMX_STAT_BINMULT;
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if (i == DMX_STAT_BINS-1) ++s->bins[i];
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/* Actually do the work of printing out the human-readable message. */
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static CARD32 dmxStatCallback(OsTimerPtr timer, CARD32 t, pointer arg)
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static int header = 0;
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int limit = dmxNumScreens;
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if (!dmxNumScreens) {
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return DMX_STAT_INTERVAL;
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if (!header++ || !(header % 10)) {
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" S SyncCount Sync/s avSync mxSync avPend mxPend | "
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if (dmxStatDisplays && dmxStatDisplays < limit) limit = dmxStatDisplays;
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for (i = 0; i < limit; i++) {
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DMXScreenInfo *dmxScreen = &dmxScreens[i];
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DMXStatInfo *s = dmxScreen->stat;
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unsigned long aSync, mSync;
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unsigned long aPend, mPend;
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aSync = avg(&s->usec, &mSync);
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aPend = avg(&s->pending, &mPend);
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dmxLog(dmxDebug, "%2d %9lu %7lu %6lu %6lu %6lu %6lu |",
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s->syncCount, /* SyncCount */
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- s->oldSyncCount) * 1000 / dmxStatInterval, /* Sync/s */
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mSync, /* max/Sync */
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mPend); /* maxPend */
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for (j = 0; j < DMX_STAT_BINS; j++)
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dmxLogCont(dmxDebug, " %5lu", s->bins[j]);
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dmxLogCont(dmxDebug, "\n");
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s->oldSyncCount = s->syncCount;
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for (j = 0; j < DMX_STAT_BINS; j++) s->bins[j] = 0;
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return DMX_STAT_INTERVAL; /* Place on queue again */
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/** Try to initialize the statistic gathering and printing routines.
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* Initialization only takes place if #dmxStatActivate has already been
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* called. We don't need the same generation protection that we used in
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* dmxSyncInit because our timer is always on a queue -- hence, server
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* generation will always free it. */
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void dmxStatInit(void)
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dmxStatTimer = TimerSet(NULL, 0,
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dmxStatInterval, dmxStatCallback, NULL);