From: Bhavesh Davda <bhavesh@xxxxxxxxxx>
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: 00278
Histogram Overflow instances:
09373 09374 09375 09376 09377 09378 09379 09380 09381 09382 # 00268 others
Signed-off-by: Bhavesh Davda <bhavesh@xxxxxxxxxx>
---
src/cyclictest/cyclictest.c | 32 +++++++++++++++++++++++++++-----
1 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index 731b4bd..31131ad 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -147,6 +147,7 @@ struct thread_stat {
double avg;
long *values;
long *hist_array;
+ unsigned long *outliers;
pthread_t thread;
int threadstarted;
int tid;
@@ -154,6 +155,8 @@ struct thread_stat {
long redmax;
long cycleofmax;
long hist_overflow;
+ long num_outliers;
+ long outliers_overflow;
};
static int shutdown;
@@ -756,8 +759,13 @@ 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 - 1;
+ else
+ stat->outliers_overflow++;
+ }
else
stat->hist_array[diff]++;
}
@@ -1226,7 +1234,7 @@ static void print_tids(struct thread_param *par[], int nthreads)
static void print_hist(struct thread_param *par[], int nthreads)
{
- int i, j;
+ int i, j, k;
unsigned long long int log_entries[nthreads+1];
unsigned long maxmax, alloverflows;
@@ -1280,9 +1288,19 @@ static void print_hist(struct thread_param *par[], int nthreads)
printf("# Histogram Overflows:");
alloverflows = 0;
for (j = 0; j < nthreads; j++) {
- printf(" %05lu", par[j]->stats->hist_overflow);
+ printf(" %05lu", par[j]->stats->hist_overflow);
alloverflows += par[j]->stats->hist_overflow;
}
+ printf("\n");
+ printf("# Histogram Overflow instances:\n");
+ for (j = 0; j < nthreads; j++) {
+ for (k = 0; k < par[j]->stats->num_outliers; k++)
+ printf(" %05lu", par[j]->stats->outliers[k]);
+ if (par[j]->stats->outliers_overflow > 0)
+ printf(" # %05lu others", par[j]->stats->outliers_overflow);
+ printf("\n");
+ }
+
if (histofall && nthreads > 1)
printf(" %05lu", alloverflows);
printf("\n");
@@ -1434,10 +1452,12 @@ 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) {
@@ -1553,8 +1573,10 @@ 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) {
--
1.7.1
--
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