On short runs it is possible to get no samples on a cpu, like this

rtla timerlat hist -P f:95 -u -c0-11 -E3500 -T50'

Index IRQ-001 Thr-001 Usr-001 IRQ-002 Thr-002 Usr-002 2 1 0 0 0 0 0 33 0 1 0 0 0 0 36 0 0 1 0 0 0 49 0 0 0 1 0 0 52 0 0 0 0 1 0 over: 0 0 0 0 0 0 count: 1 1 1 1 1 0 min: 2 33 36 49 52 18446744073709551615 avg: 2 33 36 49 52 - max: 2 33 36 49 52 0 rtla timerlat hit stop tracing IRQ handler delay: (exit from idle) 48.21 us (91.09 %) IRQ latency: 49.11 us Timerlat IRQ duration: 2.17 us (4.09 %) Blocking thread: 1.01 us (1.90 %) swapper/2:0 1.01 us ------------------------------------------------------------------------ Thread latency: 52.93 us (100%)Max timerlat IRQ latency from idle: 49.11 us in cpu 2

Note, the value 18446744073709551615 is the same as ~0 Fix this by reporting no results for the min, avg and max if the count is 0

This solution came from Daniel Bristot de Oliveria bristot@kernel.org

Fixes: 1eeb6328e8b3 ("rtla/timerlat: Add timerlat hist mode") Tested-by: John Kacur jkacur@redhat.com Signed-off-by: John Kacur jkacur@redhat.com --- tools/tracing/rtla/src/timerlat_hist.c | 60 ++++++++++++++++++-------- 1 file changed, 42 insertions(+), 18 deletions(-)

diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c index 8bd51aab6513..5b869caed10d 100644 --- a/tools/tracing/rtla/src/timerlat_hist.c +++ b/tools/tracing/rtla/src/timerlat_hist.c @@ -324,17 +324,29 @@ timerlat_print_summary(struct timerlat_hist_params *params, if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count) continue;

- if (!params->no_irq) - trace_seq_printf(trace->seq, "%9llu ", - data->hist[cpu].min_irq); + if (!params->no_irq) { + if (data->hist[cpu].irq_count) + trace_seq_printf(trace->seq, "%9llu ", + data->hist[cpu].min_irq); + else + trace_seq_printf(trace->seq, " - "); + }

- if (!params->no_thread) - trace_seq_printf(trace->seq, "%9llu ", - data->hist[cpu].min_thread); + if (!params->no_thread) { + if (data->hist[cpu].thread_count) + trace_seq_printf(trace->seq, "%9llu ", + data->hist[cpu].min_thread); + else + trace_seq_printf(trace->seq, " - "); + }

- if (params->user_hist) - trace_seq_printf(trace->seq, "%9llu ", - data->hist[cpu].min_user); + if (params->user_hist) { + if (data->hist[cpu].user_count) + trace_seq_printf(trace->seq, "%9llu ", + data->hist[cpu].min_user); + else + trace_seq_printf(trace->seq, " - "); + } } trace_seq_printf(trace->seq, "\n");

@@ -384,17 +396,29 @@ timerlat_print_summary(struct timerlat_hist_params *params, if (!data->hist[cpu].irq_count && !data->hist[cpu].thread_count) continue;

- if (!params->no_irq) - trace_seq_printf(trace->seq, "%9llu ", - data->hist[cpu].max_irq); + if (!params->no_irq) { + if (data->hist[cpu].irq_count) + trace_seq_printf(trace->seq, "%9llu ", + data->hist[cpu].max_irq); + else + trace_seq_printf(trace->seq, " - "); + }

- if (!params->no_thread) - trace_seq_printf(trace->seq, "%9llu ", - data->hist[cpu].max_thread); + if (!params->no_thread) { + if (data->hist[cpu].thread_count) + trace_seq_printf(trace->seq, "%9llu ", + data->hist[cpu].max_thread); + else + trace_seq_printf(trace->seq, " - "); + }

- if (params->user_hist) - trace_seq_printf(trace->seq, "%9llu ", - data->hist[cpu].max_user); + if (params->user_hist) { + if (data->hist[cpu].user_count) + trace_seq_printf(trace->seq, "%9llu ", + data->hist[cpu].max_user); + else + trace_seq_printf(trace->seq, " - "); + } } trace_seq_printf(trace->seq, "\n"); trace_seq_do_printf(trace->seq);