timer stats: Add a 'Collection: active/inactive' line to timer usage statistics

We can enable/disable timer statistics collection via:

  echo [1|0] > /proc/timers_stats

and it would be nice if apps had the ability to check
what the current collection status is.

This patch adds a 'Collection: active/inactive' line to display the
current timer collection status.

Also bump up the timer stats version to v0.3.

Signed-off-by: Dong Zhu <bluezhudong@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20131010075618.GH2139@zhudong.nay.redhat.com
[ Improved the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c
index 0b537f27b5591d5300427fffa4948619c0d0f4d3..1fb08f21302ece707ac7ea3b5210863cae8b19c2 100644 (file)
--- a/kernel/time/timer_stats.c
+++ b/kernel/time/timer_stats.c
@@ -298,15 +298,15 @@ static int tstats_show(struct seq_file *m, void *v)
        period = ktime_to_timespec(time);
        ms = period.tv_nsec / 1000000;
 
-       seq_puts(m, "Timer Stats Version: v0.2\n");
+       seq_puts(m, "Timer Stats Version: v0.3\n");
        seq_printf(m, "Sample period: %ld.%03ld s\n", period.tv_sec, ms);
        if (atomic_read(&overflow_count))
-               seq_printf(m, "Overflow: %d entries\n",
-                       atomic_read(&overflow_count));
+               seq_printf(m, "Overflow: %d entries\n", atomic_read(&overflow_count));
+       seq_printf(m, "Collection: %s\n", timer_stats_active ? "active" : "inactive");
 
        for (i = 0; i < nr_entries; i++) {
                entry = entries + i;
-               if (entry->timer_flag & TIMER_STATS_FLAG_DEFERRABLE) {
+               if (entry->timer_flag & TIMER_STATS_FLAG_DEFERRABLE) {
                        seq_printf(m, "%4luD, %5d %-16s ",
                                entry->count, entry->pid, entry->comm);
                } else {