perf sched map: Display only given cpus

Introducing --cpus option that will display only given cpus. Could be
used together with color-cpus option.

$ perf sched map --cpus 0,1
*A0 309999.786924 secs A0 => rcu_sched:7
*. 309999.786930 secs
*B0 . 309999.786931 secs B0 => rcuos/2:25
B0 *A0 309999.786947 secs

Signed-off-by: Jiri Olsa <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
[ Added entry to man page ]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-sched.txt

···
 	Show only CPUs with activity. Helps visualizing on high core
 	count systems.
 
+--cpus::
+	Show just entries with activities for the given CPUs.
+
 --color-cpus::
 	Highlight the given cpus.
 

tools/perf/builtin-sched.c

···
 	const char		*color_pids_str;
 	struct cpu_map		*color_cpus;
 	const char		*color_cpus_str;
+	struct cpu_map		*cpus;
+	const char		*cpus_str;
 };
 
 struct perf_sched {
···
 		if (curr_thread && thread__has_color(curr_thread))
 			pid_color = COLOR_PIDS;
 
+		if (sched->map.cpus && !cpu_map__has(sched->map.cpus, cpu))
+			continue;
+
 		if (sched->map.color_cpus && cpu_map__has(sched->map.color_cpus, cpu))
 			cpu_color = COLOR_CPUS;
 
···
 		else
 			color_fprintf(stdout, color, "   ");
 	}
+
+	if (sched->map.cpus && !cpu_map__has(sched->map.cpus, this_cpu))
+		goto out;
 
 	color_fprintf(stdout, color, "  %12.6f secs ", (double)timestamp/1e9);
 	if (new_shortname) {
···
 	if (sched->map.comp && new_cpu)
 		color_fprintf(stdout, color, " (CPU %d)", this_cpu);
 
+out:
 	color_fprintf(stdout, color, "\n");
 
 	thread__put(sched_in);
···
 
 static int setup_map_cpus(struct perf_sched *sched)
 {
+	struct cpu_map *map;
+
 	sched->max_cpu  = sysconf(_SC_NPROCESSORS_CONF);
 
 	if (sched->map.comp) {
···
 			return -1;
 	}
 
+	if (!sched->map.cpus_str)
+		return 0;
+
+	map = cpu_map__new(sched->map.cpus_str);
+	if (!map) {
+		pr_err("failed to get cpus map from %s\n", sched->map.cpus_str);
+		return -1;
+	}
+
+	sched->map.cpus = map;
 	return 0;
 }
 
···
 		   "highlight given pids in map"),
 	OPT_STRING(0, "color-cpus", &sched.map.color_cpus_str, "cpus",
                     "highlight given CPUs in map"),
+	OPT_STRING(0, "cpus", &sched.map.cpus_str, "cpus",
+                    "display given CPUs in map"),
 	OPT_END()
 	};
 	const char * const latency_usage[] = {