[PATCH] perf sched map: Add command-name option to filter the output map

[Madadi Vineeth Reddy]

By default, perf sched map prints sched-in events for all the tasks
which may not be required all the time as it prints lot of symbols
and rows to the terminal.

With --command-name option, one could specify the specific command
for which the map has to be shown. This would help in analyzing the
CPU usage patterns easier for that specific command. Since multiple
PID's might have the same command name, using command-name filter
would be more useful for debugging.

For other tasks, instead of printing the symbol, ** is printed and
the same . is used to represent idle. ** is used instead of symbol
for other tasks because it helps in clear visualization of command
of interest and secondly the symbol itself doesn't mean anything
because the sched-in of that symbol will not be printed(first sched-in
contains pid and the corresponding symbol).

6.8.0
======
  *A0                   213864.670142 secs A0 => migration/0:18
  *.                    213864.670148 secs .  => swapper:0
   .  *B0               213864.670217 secs B0 => migration/1:21
   .  *.                213864.670223 secs
   .   .  *C0           213864.670247 secs C0 => migration/2:26
   .   .  *.            213864.670252 secs

6.8.0 + patch (--command-name = schbench)
=============
   **  .   ** *A0       213864.671055 secs A0 => schbench:104834
  *B0  .   .   A0       213864.671156 secs B0 => schbench:104835
  *C0  .   .   A0       213864.671187 secs C0 => schbench:104836
  *D0  .   .   A0       213864.671219 secs D0 => schbench:104837
  *E0  .   .   A0       213864.671250 secs E0 => schbench:104838
   E0  .  *D0  A0

This helps in visualizing how a benchmark like schbench is spread over
the available cpus while also knowing which cpus are idle(.) and which
are not(**). This will be more useful as number of CPUs increase.

Signed-off-by: Madadi Vineeth Reddy <vineethr@xxxxxxxxxxxxx>
---
 tools/perf/Documentation/perf-sched.txt |  4 ++++
 tools/perf/builtin-sched.c              | 17 ++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt
index 5fbe42bd599b..b04a37560935 100644
--- a/tools/perf/Documentation/perf-sched.txt
+++ b/tools/perf/Documentation/perf-sched.txt
@@ -94,6 +94,10 @@ OPTIONS for 'perf sched map'
 --color-pids::
 	Highlight the given pids.
 
+--command-name::
+	Map output only for the given command name.
+	(** indicates other tasks while . is idle).
+
 OPTIONS for 'perf sched timehist'
 ---------------------------------
 -k::
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 0fce7d8986c0..e60836da53e5 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -156,6 +156,7 @@ struct perf_sched_map {
 	const char		*color_pids_str;
 	struct perf_cpu_map	*color_cpus;
 	const char		*color_cpus_str;
+	const char		*command;
 	struct perf_cpu_map	*cpus;
 	const char		*cpus_str;
 };
@@ -1594,8 +1595,6 @@ 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")) {
@@ -1605,7 +1604,8 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 			 */
 			tr->shortname[0] = '.';
 			tr->shortname[1] = ' ';
-		} else {
+		} else if (!sched->map.command || !strcmp(thread__comm_str(sched_in),
+								sched->map.command)) {
 			tr->shortname[0] = sched->next_shortname1;
 			tr->shortname[1] = sched->next_shortname2;
 
@@ -1618,10 +1618,18 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 				else
 					sched->next_shortname2 = '0';
 			}
+		} else {
+			tr->shortname[0] = '*';
+			tr->shortname[1] = '*';
 		}
 		new_shortname = 1;
 	}
 
+	if (sched->map.command && strcmp(thread__comm_str(sched_in), sched->map.command))
+		goto skip;
+
+	printf("  ");
+
 	for (i = 0; i < cpus_nr; i++) {
 		struct perf_cpu cpu = {
 			.cpu = sched->map.comp ? sched->map.comp_cpus[i].cpu : i,
@@ -1678,6 +1686,7 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 out:
 	color_fprintf(stdout, color, "\n");
 
+skip:
 	thread__put(sched_in);
 
 	return 0;
@@ -3560,6 +3569,8 @@ int cmd_sched(int argc, const char **argv)
                     "highlight given CPUs in map"),
 	OPT_STRING(0, "cpus", &sched.map.cpus_str, "cpus",
                     "display given CPUs in map"),
+	OPT_STRING(0, "command-name", &sched.map.command, "command",
+		"map output only for the given command name"),
 	OPT_PARENT(sched_options)
 	};
 	const struct option timehist_options[] = {
-- 
2.39.1