Re: [PATCH] cyclictest histogram overflow instance tracking

[Frank Rowand <frank.rowand@am.sony.com>]

On 10/15/12 09:38, Bhavesh Davda wrote:
> Hello Frank,
> 
> Friendly ping, to make sure this doesn't fall through the cracks.

You need to ping Clark Williams or John Kacur (not sure which...).

> 
> Thanks
> 
> - Bhavesh
> 
> On Oct 11, 2012, at 1:59 PM, Bhavesh Davda wrote:
> 
>> Thanks for the review, Frank.
>>
>> On Oct 11, 2012, at 12:57 PM, Frank Rowand wrote:
>>> Nice idea…
>> Thanks
>>
>>> Suggest:
>>>       printf("# Histogram Overflows at cycle number:");
>>>
>> Done
>>
>>>> - 		printf(" %05lu", par[j]->stats->hist_overflow);
>>>> +		printf(" %05lu", par[j]->stats->hist_overflow);
>>>
>>> Am I blind, or is that a whitespace change?  (The latest version I have does not seem
>>> to have any white space issues in that line.)
>>>
>> Turns out I had removed extraneous whitespace. My vim settings allow me to see extraneous whitespaces in red, so I get annoyed by them and can fix them up. So I've removed a few more in the revised diffs (sorry!)
>>
>>> Suggest:
>>>
>>> +             printf("# thread %d:", j);
>>>
>> Done
>>
>>> Nit: You don't need stats->outliers_overflow.  You can calculate it from
>>> stats->hist_overflow - stats->num_outliers:
>>>
>> Nice catch! I've removed outliers_overflow now.
>>
>>
>> From: Bhavesh Davda <bhavesh@vmware.com>
>>
>> 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: 00000 00253 00000 00005 00000 00024 00003 00005
>>  Histogram Overflow at cycle number:
>>  Thread 0:
>>  Thread 1: 00023 00028 00337 00338 00339 00340 00341 00342 00343 00344 # 00243 others
>>  Thread 2:
>>  Thread 3: 10486 10487 10488 10489 10490
>>  Thread 4:
>>  Thread 5: 00002 00004 00008 00012 00178 10458 10459 10460 10461 10462 # 00014 others
>>  Thread 6: 05954 08954 29955
>>  Thread 7: 20536 20537 20538 20539 20540
>>  ...
>>
>> Signed-off-by: Bhavesh Davda <bhavesh@vmware.com>
>> ---
>> src/cyclictest/cyclictest.c |   38 +++++++++++++++++++++++++++++---------
>> 1 files changed, 29 insertions(+), 9 deletions(-)
>>
>> diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
>> index 731b4bd..dc985de 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 +155,7 @@ struct thread_stat {
>> 	long redmax;
>> 	long cycleofmax;
>> 	long hist_overflow;
>> +        long num_outliers;
>> };
>>
>> static int shutdown;
>> @@ -756,8 +758,11 @@ 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 - 1;
>> +			}
>> 			else
>> 				stat->hist_array[diff]++;
>> 		}
>> @@ -811,7 +816,7 @@ static void display_help(int error)
>> 		if (kernvar(O_RDONLY, "available_tracers", tracers, sizeof(tracers)))
>> 			strcpy(tracers, "none");
>> 	}
>> -		
>> +
>> 	printf("cyclictest V %1.2f\n", VERSION_STRING);
>> 	printf("Usage:\n"
>> 	       "cyclictest <options>\n\n"
>> @@ -1188,7 +1193,7 @@ static int check_kernel(void)
>> 		kv = KV_30;
>> 		strcpy(functiontracer, "function");
>> 		strcpy(traceroptions, "trace_options");
>> -		
>> +
>> 	} else
>> 		kv = KV_NOT_SUPPORTED;
>>
>> @@ -1226,7 +1231,7 @@ 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;
>>
>> @@ -1270,7 +1275,7 @@ static void print_hist(struct thread_param *par[], int nthreads)
>> 	printf("# Max Latencies:");
>> 	maxmax = 0;
>> 	for (j = 0; j < nthreads; j++) {
>> - 		printf(" %05lu", par[j]->stats->max);
>> +		printf(" %05lu", par[j]->stats->max);
>> 		if (par[j]->stats->max > maxmax)
>> 			maxmax = par[j]->stats->max;
>> 	}
>> @@ -1280,9 +1285,20 @@ 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 at cycle number:\n");
>> +	for (j = 0; j < nthreads; j++) {
>> +		printf("# Thread %d:", j);
>> +		for (k = 0; k < par[j]->stats->num_outliers; k++)
>> +			printf(" %05lu", par[j]->stats->outliers[k]);
>> +		if (par[j]->stats->num_outliers < par[j]->stats->hist_overflow)
>> +			printf(" # %05lu others", par[j]->stats->hist_overflow - par[j]->stats->num_outliers);
>> +                printf("\n");
>> +        }
>> +
>> 	if (histofall && nthreads > 1)
>> 		printf(" %05lu", alloverflows);
>> 	printf("\n");
>> @@ -1434,10 +1450,12 @@ 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 +1571,10 @@ 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) {
>> @@ -1564,7 +1584,7 @@ int main(int argc, char **argv)
>> 			printf("# Break value: %lu\n", break_thread_value);
>> 		}
>> 	}
>> -	
>> +
>>
>> 	for (i=0; i < num_threads; i++) {
>> 		if (!statistics[i])
>> -- 
>> 1.7.1
>>
> 
> --
> Bhavesh Davda
> bhavesh@vmware.com


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