linux-kernel - [PATCH V3 1/9] perf report: Fix --total-cycles --stdio output error

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Message-Id: <20240813160208.2493643-2-kan.liang@linux.intel.com>
Date: Tue, 13 Aug 2024 09:02:00 -0700
From: kan.liang@...ux.intel.com
To: acme@...nel.org,
	namhyung@...nel.org,
	irogers@...gle.com,
	peterz@...radead.org,
	mingo@...nel.org,
	linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org
Cc: adrian.hunter@...el.com,
	ak@...ux.intel.com,
	eranian@...gle.com,
	Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V3 1/9] perf report: Fix --total-cycles --stdio output error

From: Kan Liang <kan.liang@...ux.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")
Acked-by: Namhyung Kim <namhyung@...nel.org>
Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Kan Liang <kan.liang@...ux.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 dfb47fa85e5c..04b9a5c1bc7e 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