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cyclictest: histogram overflow instance tracking 

Add feature to cyclictest histogram mode to track cycle counts every time a
sample overflows the histogram limit. This should help identify if there is a
timing pattern to jitters in cyclictest runs.

Example output (with -h 10):
 ...
 Histogram Overflows: 00001 00007 00000 00009 00004 00007 00000 00001
 Histogram Overflow at cycle number:
 Thread 0: 09964
 Thread 1: 00000 00004 00006 00008 00010 09962 11594
 Thread 2:
 Thread 3: 01169 04698 06782 09033 10299 11561 21517 28734 29532
 Thread 4: 11574 11580 11583 11586
 Thread 5: 00020 09448 13954 14954 18954 20587 24973
 Thread 6:
 Thread 7: 18950
 ...

Signed-off-by: Bhavesh Davda <bhavesh@vmware.com>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: John Kacur <jkacur@redhat.com>
This commit is contained in:
Bhavesh Davda 2012-10-16 10:02:53 -07:00 committed by John Kacur
parent 18cd9775e5
commit 992b905d42
1 changed files with 23 additions and 3 deletions
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26
src/cyclictest/cyclictest.c
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@ -150,6 +150,7 @@ struct thread_stat {
double avg;
long *values;
long *hist_array;
long *outliers;
pthread_t thread;
int threadstarted;
int tid;
@ -157,6 +158,7 @@ struct thread_stat {
long redmax;
long cycleofmax;
long hist_overflow;
long num_outliers;
};
static int shutdown;
@ -850,8 +852,11 @@ void *timerthread(void *param)
/* Update the histogram */
if (histogram) {
if (diff >= histogram)
if (diff >= histogram) {
stat->hist_overflow++;
if (stat->num_outliers < histogram)
stat->outliers[stat->num_outliers++] = stat->cycles;
}
else
stat->hist_array[diff]++;
}
@ -1401,6 +1406,17 @@ static void print_hist(struct thread_param *par[], int nthreads)
if (histofall && nthreads > 1)
printf(" %05lu", alloverflows);
printf("\n");
printf("# Histogram Overflow at cycle number:\n");
for (i = 0; i < nthreads; i++) {
printf("# Thread %d:", i);
for (j = 0; j < par[i]->stats->num_outliers; j++)
printf(" %05lu", par[i]->stats->outliers[j]);
if (par[i]->stats->num_outliers < par[i]->stats->hist_overflow)
printf(" # %05lu others", par[i]->stats->hist_overflow - par[i]->stats->num_outliers);
printf("\n");
}
printf("\n");
}
static void print_stat(struct thread_param *par, int index, int verbose)
@ -1549,10 +1565,12 @@ int main(int argc, char **argv)
int bufsize = histogram * sizeof(long);
stat->hist_array = threadalloc(bufsize, node);
if (stat->hist_array == NULL)
stat->outliers = threadalloc(bufsize, node);
if (stat->hist_array == NULL || stat->outliers == NULL)
fatal("failed to allocate histogram of size %d on node %d\n",
histogram, i);
memset(stat->hist_array, 0, bufsize);
memset(stat->outliers, 0, bufsize);
}
if (verbose) {
@ -1668,8 +1686,10 @@ int main(int argc, char **argv)
if (histogram) {
print_hist(parameters, num_threads);
for (i = 0; i < num_threads; i++)
for (i = 0; i < num_threads; i++) {
threadfree(statistics[i]->hist_array, histogram*sizeof(long), parameters[i]->node);
threadfree(statistics[i]->outliers, histogram*sizeof(long), parameters[i]->node);
}
}
if (tracelimit) {