On 10/15/12 16:43, John Kacur wrote:
>
>
> On Mon, 13 Aug 2012, Frank Rowand wrote:
>
> Hi Frank - I added the extra comment to your patch as you requested
> "One issue with using warn() and info() instead of fprintf() is that
> the compiler no longer warns about format mismatches."
>
> Another thing about using the warn function - I'm not sure I like that
> WARN: printed out when you use your -R
>
> ./cyclictest -R
> WARN: reported clock resolution: 1 nsec
> WARN: measured clock resolution approximately: 699 nsec
The warns could be printed "if (ct_debug && ...)" instead of
"if (verbose || ...)", because -verbose is really about printing data
for each event instead of a more traditional meaning.
>
> Nice patch though.
> Signed-off-by: John Kacur <jkacur@xxxxxxxxxx>
>>
>> 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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