perf tools: Add the ability to specify list of cpus to monitor

This patch adds a -C option to stat, record, top to designate a list of CPUs to
monitor. CPUs can be specified as a comma-separated list or ranges, no space
allowed.

Examples:
$ perf record -a -C0-1,4-7 sleep 1
$ perf top -C0-4
$ perf stat -a -C1,2,3,4 sleep 1

With perf record in per-thread mode with inherit mode on, samples are collected
only when the thread runs on the designated CPUs.

The -C option does not turn on system-wide mode automatically.

Cc: David S. Miller <davem@davemloft.net>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <4bff9496.d345d80a.41fe.7b00@mx.google.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 9a39ca3c3ac4..a6b4d44f9502 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -69,7 +69,7 @@ static struct perf_event_attr default_attrs[] = {
 };
 
 static bool                     system_wide                     =  false;
-static unsigned int             nr_cpus                         =  0;
+static int                      nr_cpus                         =  0;
 static int                      run_idx                         =  0;
 
 static int                      run_count                       =  1;
@@ -82,6 +82,7 @@ static int			thread_num			=  0;
 static pid_t                    child_pid                       = -1;
 static bool                     null_run                        =  false;
 static bool                     big_num                         =  false;
+static const char               *cpu_list;
 
 
 static int                      *fd[MAX_NR_CPUS][MAX_COUNTERS];
@@ -158,7 +159,7 @@ static int create_perf_stat_counter(int counter)
                                     PERF_FORMAT_TOTAL_TIME_RUNNING;
 
         if (system_wide) {
-                unsigned int cpu;
+                int cpu;
 
                 for (cpu = 0; cpu < nr_cpus; cpu++) {
                         fd[cpu][counter][0] = sys_perf_event_open(attr,
@@ -208,7 +209,7 @@ static inline int nsec_counter(int counter)
 static void read_counter(int counter)
 {
         u64 count[3], single_count[3];
-        unsigned int cpu;
+        int cpu;
         size_t res, nv;
         int scaled;
         int i, thread;
@@ -542,6 +543,8 @@ static const struct option options[] = {
                     "null run - dont start any counters"),
         OPT_BOOLEAN('B', "big-num", &big_num,
                     "print large numbers with thousands\' separators"),
+        OPT_STRING('C', "cpu", &cpu_list, "cpu",
+                    "list of cpus to monitor in system-wide"),
         OPT_END()
 };
 
@@ -566,10 +569,13 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
         }
 
         if (system_wide)
-                nr_cpus = read_cpu_map();
+                nr_cpus = read_cpu_map(cpu_list);
         else
                 nr_cpus = 1;
 
+        if (nr_cpus < 1)
+                usage_with_options(stat_usage, options);
+
         if (target_pid != -1) {
                 target_tid = target_pid;
                 thread_num = find_all_tid(target_pid, &all_tids);