V3: Use src/lib/error.c functions instead of fprintf.
Fix printf format warnings for 32 bit vs 64 bit systems with cast.
Fix bad continuation line white space prefix.
Remove unused variable zero_diff.
cyclictest: ARM panda clock resolution will be ~30 usec unless
CONFIG_OMAP_32K_TIMER=n, resulting in a poor latency report.
This patch does _not_ fix the problem, it merely provides the
instrumentation to make it visible. The value of measured
resolution is useful information for any system.
Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxxxxx>
---
src/cyclictest/cyclictest.c | 109 108 + 1 - 0 !
1 file changed, 108 insertions(+), 1 deletion(-)
Index: b/src/cyclictest/cyclictest.c
===================================================================
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -174,6 +174,8 @@ static int use_nsecs = 0;
static int refresh_on_max;
static int force_sched_other;
static int priospread = 0;
+static int check_clock_resolution;
+static int ct_debug;
static pthread_cond_t refresh_on_max_cond = PTHREAD_COND_INITIALIZER;
static pthread_mutex_t refresh_on_max_lock = PTHREAD_MUTEX_INITIALIZER;
@@ -944,6 +946,9 @@ static void display_help(int error)
"-q --quiet print only a summary on exit\n"
"-Q --priospread spread priority levels starting at specified value\n"
"-r --relative use relative timer instead of absolute\n"
+ "-R --resolution check clock resolution, calling clock_gettime() many\n"
+ " times. list of clock_gettime() values will be\n"
+ " reported with -X\n"
"-s --system use sys_nanosleep and sys_setitimer\n"
"-S --smp Standard SMP testing: options -a -t -n and\n"
" same priority of all threads\n"
@@ -960,6 +965,7 @@ static void display_help(int error)
" format: n:c:v n=tasknum c=count v=value in us\n"
"-w --wakeup task wakeup tracing (used with -b)\n"
"-W --wakeuprt rt task wakeup tracing (used with -b)\n"
+ "-X --dbg_cyclictest print info useful for debugging cyclictest\n"
"-y POLI --policy=POLI policy of realtime thread, POLI may be fifo(default) or rr\n"
" format: --policy=fifo(default) or --policy=rr\n",
tracers
@@ -1076,6 +1082,7 @@ static void process_options (int argc, c
{"quiet", no_argument, NULL, 'q'},
{"priospread", no_argument, NULL, 'Q'},
{"relative", no_argument, NULL, 'r'},
+ {"resolution", no_argument, NULL, 'R'},
{"system", no_argument, NULL, 's'},
{"smp", no_argument, NULL, 'S'},
{"threads", optional_argument, NULL, 't'},
@@ -1085,11 +1092,12 @@ static void process_options (int argc, c
{"verbose", no_argument, NULL, 'v'},
{"wakeup", no_argument, NULL, 'w'},
{"wakeuprt", no_argument, NULL, 'W'},
+ {"dbg_cyclictest", no_argument, NULL, 'X'},
{"policy", required_argument, NULL, 'y'},
{"help", no_argument, NULL, '?'},
{NULL, 0, NULL, 0}
};
- int c = getopt_long(argc, argv, "a::b:Bc:Cd:D:e:Efh:H:i:Il:MnNo:O:p:PmqQrsSt::uUvD:wWT:y:",
+ int c = getopt_long(argc, argv, "a::b:Bc:Cd:D:e:Efh:H:i:Il:MnNo:O:p:PmqQrRsSt::uUvD:wWXT:y:",
long_options, &option_index);
if (c == -1)
break;
@@ -1158,6 +1166,7 @@ static void process_options (int argc, c
case 'q': quiet = 1; break;
case 'Q': priospread = 1; break;
case 'r': timermode = TIMER_RELTIME; break;
+ case 'R': check_clock_resolution = 1; break;
case 's': use_system = MODE_SYS_OFFSET; break;
case 'S': /* SMP testing */
if (numa)
@@ -1202,6 +1211,7 @@ static void process_options (int argc, c
case 'v': verbose = 1; break;
case 'w': tracetype = WAKEUP; break;
case 'W': tracetype = WAKEUPRT; break;
+ case 'X': ct_debug = 1; break;
case 'y': handlepolicy(optarg); break;
case '?': display_help(0); break;
@@ -1483,6 +1493,103 @@ int main(int argc, char **argv)
if (check_timer())
warn("High resolution timers not available\n");
+ if (check_clock_resolution) {
+ int clock;
+ uint64_t diff;
+ int k;
+ uint64_t min_non_zero_diff = UINT64_MAX;
+ struct timespec now;
+ struct timespec prev;
+ uint64_t reported_resolution = UINT64_MAX;
+ struct timespec res;
+ struct timespec *time;
+ int times;
+
+ clock = clocksources[clocksel];
+
+ if (clock_getres(clock, &res)) {
+ warn("clock_getres failed");
+ } else {
+ reported_resolution = (NSEC_PER_SEC * res.tv_sec) + res.tv_nsec;
+ }
+
+
+ /*
+ * Calculate how many calls to clock_gettime are needed.
+ * Then call it that many times.
+ * Goal is to collect timestamps for ~ 0.001 sec.
+ * This will reliably capture resolution <= 500 usec.
+ */
+ times = 1000;
+ clock_gettime(clock, &prev);
+ for (k=0; k < times; k++) {
+ clock_gettime(clock, &now);
+ }
+
+ diff = calcdiff_ns(now, prev);
+ if (diff == 0) {
+ /*
+ * No clock rollover occurred.
+ * Use the default value for times.
+ */
+ times = -1;
+ } else {
+ int call_time;
+ call_time = diff / times; /* duration 1 call */
+ times = NSEC_PER_SEC / call_time; /* calls per second */
+ times /= 1000; /* calls per msec */
+ if (times < 1000)
+ times = 1000;
+ }
+ /* sanity check */
+ if ((times <= 0) || (times > 100000))
+ times = 100000;
+
+ time = calloc(times, sizeof(*time));
+
+ for (k=0; k < times; k++) {
+ clock_gettime(clock, &time[k]);
+ }
+
+ if (ct_debug) {
+ info("For %d consecutive calls to clock_gettime():\n", times);
+ info("time, delta time (nsec)\n");
+ }
+
+ prev = time[0];
+ for (k=1; k < times; k++) {
+
+ diff = calcdiff_ns(time[k], prev);
+ prev = time[k];
+
+ if (diff && (diff < min_non_zero_diff)) {
+ min_non_zero_diff = diff;
+ }
+
+ if (ct_debug)
+ info("%ld.%06ld %5llu\n",
+ time[k].tv_sec, time[k].tv_nsec,
+ (unsigned long long)diff);
+ }
+
+ free(time);
+
+
+ if (verbose ||
+ (min_non_zero_diff && (min_non_zero_diff > reported_resolution))) {
+ /*
+ * Measured clock resolution includes the time to call
+ * clock_gettime(), so it will be slightly larger than
+ * actual resolution.
+ */
+ warn("reported clock resolution: %llu nsec\n",
+ (unsigned long long)reported_resolution);
+ warn("measured clock resolution approximately: %llu nsec\n",
+ (unsigned long long)min_non_zero_diff);
+ }
+
+ }
+
mode = use_nanosleep + use_system;
sigemptyset(&sigset);
--
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