diff options
Diffstat (limited to 'src/cyclictest/cyclictest.c')
| -rw-r--r-- | src/cyclictest/cyclictest.c | 109 |
1 files changed, 108 insertions, 1 deletions
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c index e53e1ce..807041d 100644 --- a/src/cyclictest/cyclictest.c +++ b/src/cyclictest/cyclictest.c @@ -176,6 +176,8 @@ 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; @@ -949,6 +951,9 @@ 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" @@ -965,6 +970,7 @@ 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 @@ -1081,6 +1087,7 @@ static void process_options (int argc, char *argv[]) {"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'}, @@ -1090,11 +1097,12 @@ static void process_options (int argc, char *argv[]) {"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; @@ -1163,6 +1171,7 @@ static void process_options (int argc, char *argv[]) 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) @@ -1207,6 +1216,7 @@ static void process_options (int argc, char *argv[]) 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; @@ -1499,6 +1509,103 @@ 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); |