perf sched: Determine the number of CPUs automatically

For 'perf sched map' output, determine max_cpu automatically,
instead of the static default of 15.

[ v2: use sysconf() pointed out by Arjan van de Ven <arjan@infradead.org> ]

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-sched.c

@@ -1347,7 +1347,7 @@ process_sched_wakeup_event(struct raw_event_sample *raw,
  * Track the current task - that way we can know whether there's any
  * weird events, such as a task being switched away that is not current.
  */
-static int max_cpu = 15;
+static int max_cpu;
 
 static u32 curr_pid[MAX_CPUS] = { [0 ... MAX_CPUS-1] = -1 };
 
@@ -1818,6 +1818,8 @@ static struct trace_sched_handler map_ops  = {
 
 static void __cmd_map(void)
 {
+	max_cpu = sysconf(_SC_NPROCESSORS_CONF);
+
 	setup_pager();
 	read_events();
 	print_bad_events();