perf sched map: Add task-name option to filter the output map

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

When using the --task-name option, the sched-out time is represented
by a '*-'. Since not all task sched-in events are printed, the sched-out
time of the relevant task might be lost. This representation ensures
that the sched-out time of the interested task is not overlooked.

6.10.0-rc1
==========
*A0                              131040.639793 secs A0 => migration/0:19
*.                               131040.639801 secs .  => swapper:0
 .  *B0                          131040.639830 secs B0 => migration/1:24
 .  *.                           131040.639836 secs
 .   .  *C0                      131040.640108 secs C0 => migration/2:30
 .   .  *.                       131040.640163 secs
 .   .   .  *D0                  131040.640386 secs D0 => migration/3:36
 .   .   .  *.                   131040.640395 secs

6.10.0-rc1 + patch (--task-name wdavdaemon)
=============
 .  *A0  .   .   .   .   -   .   131040.641346 secs A0 => wdavdaemon:62509
 .   A0 *B0  .   .   .   -   .   131040.641378 secs B0 => wdavdaemon:62274
 -  *-   B0  .   .   .   -   .   131040.641379 secs
*C0  .   B0  .   .   .   .   .   131040.641572 secs C0 => wdavdaemon:62283
 C0  .   B0  .  *D0  .   .   .   131040.641572 secs D0 => wdavdaemon:62277
 C0  .   B0  .   D0  .  *E0  .   131040.641578 secs E0 => wdavdaemon:62270
*-   .   B0  .   D0  .   E0  .   131040.641581 secs
 .   .   B0  .   D0  .  *-   .   131040.641583 secs
Reviewed-and-tested-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Cc: Chen Yu <yu.c.chen@intel.com>
Link: https://lore.kernel.org/r/20240707182716.22054-2-vineethr@linux.ibm.comSigned-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/Documentation/perf-sched.txt

@@ -130,6 +130,12 @@ OPTIONS for 'perf sched map'
 --color-pids::
 	Highlight the given pids.
 
+--task-name <task>::
+	Map output only for the given task name. The sched-out
+	time is printed and is represented by '*-' for the given
+	task name
+	('-' indicates other tasks while '.' is idle).
+
 OPTIONS for 'perf sched timehist'
 ---------------------------------
 -k::

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		*task_name;
 	struct perf_cpu_map	*cpus;
 	const char		*cpus_str;
 };
@@ -177,6 +178,7 @@ struct perf_sched {
 	struct perf_cpu	 max_cpu;
 	u32		 *curr_pid;
 	struct thread	 **curr_thread;
+	struct thread	 **curr_out_thread;
 	char		 next_shortname1;
 	char		 next_shortname2;
 	unsigned int	 replay_repeat;
@@ -1538,23 +1540,75 @@ map__findnew_thread(struct perf_sched *sched, struct machine *machine, pid_t pid
 	return thread;
 }
 
+static void print_sched_map(struct perf_sched *sched, struct perf_cpu this_cpu, int cpus_nr,
+								const char *color, bool sched_out)
+{
+	for (int i = 0; i < cpus_nr; i++) {
+		struct perf_cpu cpu = {
+			.cpu = sched->map.comp ? sched->map.comp_cpus[i].cpu : i,
+		};
+		struct thread *curr_thread = sched->curr_thread[cpu.cpu];
+		struct thread *curr_out_thread = sched->curr_out_thread[cpu.cpu];
+		struct thread_runtime *curr_tr;
+		const char *pid_color = color;
+		const char *cpu_color = color;
+		char symbol = ' ';
+		struct thread *thread_to_check = sched_out ? curr_out_thread : curr_thread;
+
+		if (thread_to_check && thread__has_color(thread_to_check))
+			pid_color = COLOR_PIDS;
+
+		if (sched->map.color_cpus && perf_cpu_map__has(sched->map.color_cpus, cpu))
+			cpu_color = COLOR_CPUS;
+
+		if (cpu.cpu == this_cpu.cpu)
+			symbol = '*';
+
+		color_fprintf(stdout, cpu.cpu != this_cpu.cpu ? color : cpu_color, "%c", symbol);
+
+		thread_to_check = sched_out ? sched->curr_out_thread[cpu.cpu] :
+								sched->curr_thread[cpu.cpu];
+
+		if (thread_to_check) {
+			curr_tr = thread__get_runtime(thread_to_check);
+			if (curr_tr == NULL)
+				return;
+
+			if (sched_out) {
+				if (cpu.cpu == this_cpu.cpu)
+					color_fprintf(stdout, color, "-  ");
+				else {
+					curr_tr = thread__get_runtime(sched->curr_thread[cpu.cpu]);
+					if (curr_tr != NULL)
+						color_fprintf(stdout, pid_color, "%2s ",
+										curr_tr->shortname);
+				}
+			} else
+				color_fprintf(stdout, pid_color, "%2s ", curr_tr->shortname);
+		} else
+			color_fprintf(stdout, color, "   ");
+	}
+}
+
 static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 			    struct perf_sample *sample, struct machine *machine)
 {
 	const u32 next_pid = evsel__intval(evsel, sample, "next_pid");
-	struct thread *sched_in;
+	const u32 prev_pid = evsel__intval(evsel, sample, "prev_pid");
+	struct thread *sched_in, *sched_out;
 	struct thread_runtime *tr;
 	int new_shortname;
 	u64 timestamp0, timestamp = sample->time;
 	s64 delta;
-	int i;
 	struct perf_cpu this_cpu = {
 		.cpu = sample->cpu,
 	};
 	int cpus_nr;
+	int proceed;
 	bool new_cpu = false;
 	const char *color = PERF_COLOR_NORMAL;
 	char stimestamp[32];
+	const char *str;
 
 	BUG_ON(this_cpu.cpu >= MAX_CPUS || this_cpu.cpu < 0);
 
@@ -1583,7 +1637,8 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 	}
 
 	sched_in = map__findnew_thread(sched, machine, -1, next_pid);
-	if (sched_in == NULL)
+	sched_out = map__findnew_thread(sched, machine, -1, prev_pid);
+	if (sched_in == NULL || sched_out == NULL)
 		return -1;
 
 	tr = thread__get_runtime(sched_in);
@@ -1593,7 +1648,9 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 	}
 
 	sched->curr_thread[this_cpu.cpu] = thread__get(sched_in);
+	sched->curr_out_thread[this_cpu.cpu] = thread__get(sched_out);
 
+	str = thread__comm_str(sched_in);
 	new_shortname = 0;
 	if (!tr->shortname[0]) {
 		if (!strcmp(thread__comm_str(sched_in), "swapper")) {
@@ -1603,7 +1660,7 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 			 */
 			tr->shortname[0] = '.';
 			tr->shortname[1] = ' ';
-		} else {
+		} else if (!sched->map.task_name || !strcmp(str, sched->map.task_name)) {
 			tr->shortname[0] = sched->next_shortname1;
 			tr->shortname[1] = sched->next_shortname2;
 
@@ -1616,6 +1673,9 @@ 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;
 	}
@@ -1623,42 +1683,28 @@ static int map_switch_event(struct perf_sched *sched, struct evsel *evsel,
 	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,
-		};
-		struct thread *curr_thread = sched->curr_thread[cpu.cpu];
-		struct thread_runtime *curr_tr;
-		const char *pid_color = color;
-		const char *cpu_color = color;
-
-		if (curr_thread && thread__has_color(curr_thread))
-			pid_color = COLOR_PIDS;
-
-		if (sched->map.cpus && !perf_cpu_map__has(sched->map.cpus, cpu))
-			continue;
-
-		if (sched->map.color_cpus && perf_cpu_map__has(sched->map.color_cpus, cpu))
-			cpu_color = COLOR_CPUS;
-
-		if (cpu.cpu != this_cpu.cpu)
-			color_fprintf(stdout, color, " ");
+	proceed = 0;
+	str = thread__comm_str(sched_in);
+	/*
+	 * Check which of sched_in and sched_out matches the passed --task-name
+	 * arguments and call the corresponding print_sched_map.
+	 */
+	if (sched->map.task_name && strcmp(str, sched->map.task_name)) {
+		if (strcmp(thread__comm_str(sched_out), sched->map.task_name))
+			goto out;
 		else
-			color_fprintf(stdout, cpu_color, "*");
+			goto sched_out;
 
-		if (sched->curr_thread[cpu.cpu]) {
-			curr_tr = thread__get_runtime(sched->curr_thread[cpu.cpu]);
-			if (curr_tr == NULL) {
-				thread__put(sched_in);
-				return -1;
-			}
-			color_fprintf(stdout, pid_color, "%2s ", curr_tr->shortname);
-		} else
-			color_fprintf(stdout, color, "   ");
+	} else {
+		str = thread__comm_str(sched_out);
+		if (!(sched->map.task_name && strcmp(str, sched->map.task_name)))
+			proceed = 1;
 	}
 
+	printf("  ");
+
+	print_sched_map(sched, this_cpu, cpus_nr, color, false);
+
 	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 +1721,32 @@ 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);
 
+	if (proceed != 1) {
+		color_fprintf(stdout, color, "\n");
+		goto out;
+	}
+
+sched_out:
+	if (sched->map.task_name) {
+		tr = thread__get_runtime(sched->curr_out_thread[this_cpu.cpu]);
+		if (strcmp(tr->shortname, "") == 0)
+			goto out;
+
+		if (proceed == 1)
+			color_fprintf(stdout, color, "\n");
+
+		printf("  ");
+		print_sched_map(sched, this_cpu, cpus_nr, color, true);
+		timestamp__scnprintf_usec(timestamp, stimestamp, sizeof(stimestamp));
+		color_fprintf(stdout, color, "  %12s secs ", stimestamp);
+	}
+
 	color_fprintf(stdout, color, "\n");
 
 out:
+	if (sched->map.task_name)
+		thread__put(sched_out);
+
 	thread__put(sched_in);
 
 	return 0;
@@ -3310,6 +3379,10 @@ static int perf_sched__map(struct perf_sched *sched)
 	if (!sched->curr_thread)
 		return rc;
 
+	sched->curr_out_thread = calloc(MAX_CPUS, sizeof(*(sched->curr_out_thread)));
+	if (!sched->curr_out_thread)
+		return rc;
+
 	if (setup_cpus_switch_event(sched))
 		goto out_free_curr_thread;
 
@@ -3566,6 +3639,8 @@ 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, "task-name", &sched.map.task_name, "task",
+		"map output only for the given task name"),
 	OPT_PARENT(sched_options)
 	};
 	const struct option timehist_options[] = {