Messages in this thread Patch in this message |  | | Date | Sat, 24 Dec 2022 12:39:15 +0000 | From | Andreas Ziegler <> | Subject | rtla osnoise hist: average duration is always zero |
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-- Observed in, but not limited to, Linux 6.1.1
Dear all,
rtla osnoise hist always outputs '0' as average duration value. Example:
# rtla osnoise hist -P F:1 -c 0-1 -r 900000 -d 1M -b 1 -E 5000 -T 1 # RTLA osnoise histogram # Time unit is microseconds (us) # Duration: 0 00:01:00 ... count: 5629 1364 min: 1 1 avg: 0 0 max: 2955 56
This is due to sum_sample in osnoise_hist_update_multiple() being calculated as the sum (duration), not as sum (duration * count).
Rounding, instead of truncating, of the average value would be cool.
The following patch would solve the issue described above:
Sampled duration must be weighted by observed quantity, to arrive at a correct average duration value.
Fix calculation of total duration by summing (duration * count). Introduce rounding for calculation of final value.
Signed-off-by: Andreas Ziegler <br015@umbiko.net>
--- a/tools/tracing/rtla/src/osnoise_hist.c +++ b/tools/tracing/rtla/src/osnoise_hist.c @@ -121,6 +121,7 @@ { struct osnoise_hist_params *params = tool->params; struct osnoise_hist_data *data = tool->data; + unsigned long long total_duration; int entries = data->entries; int bucket; int *hist; @@ -131,10 +132,12 @@ if (data->bucket_size) bucket = duration / data->bucket_size;
+ total_duration = duration * count; + hist = data->hist[cpu].samples; data->hist[cpu].count += count; update_min(&data->hist[cpu].min_sample, &duration); - update_sum(&data->hist[cpu].sum_sample, &duration); + update_sum(&data->hist[cpu].sum_sample, &total_duration); update_max(&data->hist[cpu].max_sample, &duration);
if (bucket < entries) @@ -333,7 +336,7 @@
if (data->hist[cpu].count) trace_seq_printf(trace->seq, "%9llu ", - data->hist[cpu].sum_sample / data->hist[cpu].count); + (data->hist[cpu].sum_sample + data->hist[cpu].count / 2) / data->hist[cpu].count); else trace_seq_printf(trace->seq, " - "); }
Kind regards, Andreas
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