linux-kernel - [PATCH] perf: sched map skips redundant lines with cpu filters

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Message-ID: <20240614073517.94974-1-sieberf@amazon.com>
Date: Fri, 14 Jun 2024 09:35:17 +0200
From: Fernand Sieber <sieberf@...zon.com>
To:
CC: <linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Fernand Sieber <sieberf@...zon.com>, Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Arnaldo Carvalho de Melo <acme@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Subject: [PATCH] perf: sched map skips redundant lines with cpu filters

perf sched map supports cpu filter.
However, even with cpu filters active, any context switch currently
corresponds to a separate line.
As result, context switches on irrelevant cpus result to redundant lines,
which makes the output particlularly difficult to read on wide
architectures.

Fix it by skipping printing for irrelevant CPUs.

Example snippet of output before fix:

  *B0       1.461147 secs
   B0
   B0
   B0
  *G0       1.517139 secs

After fix:

  *B0       1.461147 secs
  *G0       1.517139 secs

Signed-off-by: Fernand Sieber <sieberf@...zon.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
---
 tools/perf/builtin-sched.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 7422c930abaf..aa59f763ca46 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1594,8 +1594,6 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 
 	sched->curr_thread[this_cpu.cpu] = thread__get(sched_in);
 
-	printf("  ");
-
 	new_shortname = 0;
 	if (!tr->shortname[0]) {
 		if (!strcmp(thread__comm_str(sched_in), "swapper")) {
@@ -1622,6 +1620,11 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 		new_shortname = 1;
 	}
 
+	if (sched->map.cpus && !perf_cpu_map__has(sched->map.cpus, this_cpu))
+		goto out;
+
+	printf("  ");
+
 	for (i = 0; i < cpus_nr; i++) {
 		struct perf_cpu cpu = {
 			.cpu = sched->map.comp ? sched->map.comp_cpus[i].cpu : i,
@@ -1656,9 +1659,6 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 			color_fprintf(stdout, color, "   ");
 	}
 
-	if (sched->map.cpus && !perf_cpu_map__has(sched->map.cpus, this_cpu))
-		goto out;
-
 	timestamp__scnprintf_usec(timestamp, stimestamp, sizeof(stimestamp));
 	color_fprintf(stdout, color, "  %12s secs ", stimestamp);
 	if (new_shortname || tr->comm_changed || (verbose > 0 && thread__tid(sched_in))) {
@@ -1675,9 +1675,9 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 	if (sched->map.comp && new_cpu)
 		color_fprintf(stdout, color, " (CPU %d)", this_cpu);
 
-out:
 	color_fprintf(stdout, color, "\n");
 
+out:
 	thread__put(sched_in);
 
 	return 0;
-- 
2.40.1