[PATCH 1/9] perf report: Fix --total-cycles --stdio output error

kan.liang
2024-07-03T20:03:24Z

From: Kan Liang <kan.liang@linux.intel.com>

The --total-cycles may output wrong information with the --stdio.

For example,
perf record -e "{cycles,instructions}",cache-misses -b sleep 1
perf report --total-cycles --stdio

The total cycles output of {cycles,instructions} and cache-misses are
almost the same.

# Samples: 938 of events 'anon group { cycles, instructions }'
# Event count (approx.): 938
#
# Sampled Cycles% Sampled Cycles Avg Cycles% Avg Cycles
# ............... .............. ........... ..........
..................................................>
#
11.19% 2.6K 0.10% 21
[perf_iterate_ctx+48 -> >
5.79% 1.4K 0.45% 97
[__intel_pmu_enable_all.constprop.0+80 -> __intel_>
5.11% 1.2K 0.33% 71
[native_write_msr+0 ->>

# Samples: 293 of event 'cache-misses'
# Event count (approx.): 293
#
# Sampled Cycles% Sampled Cycles Avg Cycles% Avg Cycles
[>
# ............... .............. ........... ..........
..................................................>
#
11.19% 2.6K 0.13% 21
[perf_iterate_ctx+48 -> >
5.79% 1.4K 0.59% 97
[__intel_pmu_enable_all.constprop.0+80 -> __intel_>
5.11% 1.2K 0.43% 71
[native_write_msr+0 ->>

With the symbol_conf.event_group, the perf report should only report the
block information of the leader event in a group.
However, the current implementation retrieves the next event's block
information, rather than the next group leader's block information.

Make sure the index is updated even if the event is skipped.

With the patch,

# Samples: 293 of event 'cache-misses'
# Event count (approx.): 293
#
# Sampled Cycles% Sampled Cycles Avg Cycles% Avg Cycles
[>
# ............... .............. ........... ..........
..................................................>
#
37.98% 9.0K 4.05% 299
[perf_event_addr_filters_exec+0 -> perf_event_a>
11.19% 2.6K 0.28% 21
[perf_iterate_ctx+48 -> >
5.79% 1.4K 1.32% 97
[__intel_pmu_enable_all.constprop.0+80 -> __intel_>

Fixes: 6f7164fa231a ("perf report: Sort by sampled cycles percent per block for stdio")
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
tools/perf/builtin-report.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 9718770facb5..b9f22c5321da 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -565,6 +565,7 @@ static int evlist__tty_browse_hists(struct evlist *evlist, struct report *rep, c
struct hists *hists = evsel__hists(pos);
const char *evname = evsel__name(pos);

+ i++;
if (symbol_conf.event_group && !evsel__is_group_leader(pos))
continue;

@@ -574,7 +575,7 @@ static int evlist__tty_browse_hists(struct evlist *evlist, struct report *rep, c
hists__fprintf_nr_sample_events(hists, rep, evname, stdout);

if (rep->total_cycles_mode) {
- report__browse_block_hists(&rep->block_reports[i++].hist,
+ report__browse_block_hists(&rep->block_reports[i - 1].hist,
rep->min_percent, pos, NULL);
continue;
}
--
2.38.1