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, 6 deletions

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index a66f4272b994..45014ef11059 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -102,6 +102,7 @@ struct sym_entry		*sym_filter_entry_sched		=   NULL;
 static int                      sym_pcnt_filter                 =      5;
 static int                      sym_counter                     =      0;
 static int                      display_weighted                =     -1;
+static const char               *cpu_list;
 
 /*
  * Symbols
@@ -1351,8 +1352,8 @@ static const struct option options[] = {
                     "profile events on existing thread id"),
         OPT_BOOLEAN('a', "all-cpus", &system_wide,
                             "system-wide collection from all CPUs"),
-        OPT_INTEGER('C', "CPU", &profile_cpu,
-                    "CPU to profile on"),
+        OPT_STRING('C', "cpu", &cpu_list, "cpu",
+                    "list of cpus to monitor"),
         OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
                    "file", "vmlinux pathname"),
         OPT_BOOLEAN('K', "hide_kernel_symbols", &hide_kernel_symbols,
@@ -1428,10 +1429,10 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
                 return -ENOMEM;
 
         /* CPU and PID are mutually exclusive */
-        if (target_tid > 0 && profile_cpu != -1) {
+        if (target_tid > 0 && cpu_list) {
                 printf("WARNING: PID switch overriding CPU\n");
                 sleep(1);
-                profile_cpu = -1;
+                cpu_list = NULL;
         }
 
         if (!nr_counters)
@@ -1469,10 +1470,13 @@ int cmd_top(int argc, const char **argv, const char *prefix __used)
                 attrs[counter].sample_period = default_interval;
         }
 
-        if (target_tid != -1 || profile_cpu != -1)
+        if (target_tid != -1)
                 nr_cpus = 1;
         else
-                nr_cpus = read_cpu_map();
+                nr_cpus = read_cpu_map(cpu_list);
+
+        if (nr_cpus < 1)
+                usage_with_options(top_usage, options);
 
         get_term_dimensions(&winsize);
         if (print_entries == 0) {