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author | Ingo Molnar <mingo@elte.hu> | 2007-06-01 00:47:16 -0700 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-06-01 08:18:30 -0700 |
commit | c1a834dc704763673df10282995257f2de93cbe9 (patch) | |
tree | 66a0bc5ffbf6732eaa5fc6f554c13b235005c4cd /kernel/time/timer_stats.c | |
parent | 9fcc15ec3c1c287a781a4620e52522b6186f26f6 (diff) | |
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timer stats: speedups
Make timer-stats have almost zero overhead when enabled in the config but
not used. (this way distros can enable it more easily)
Also update the documentation about overhead of timer_stats - it was
written for the first version which had a global lock and a linear list
walk based lookup ;-)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/time/timer_stats.c')
-rw-r--r-- | kernel/time/timer_stats.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c index fa3d380..3216937 100644 --- a/kernel/time/timer_stats.c +++ b/kernel/time/timer_stats.c @@ -236,10 +236,15 @@ void timer_stats_update_stats(void *timer, pid_t pid, void *startf, /* * It doesnt matter which lock we take: */ - spinlock_t *lock = &per_cpu(lookup_lock, raw_smp_processor_id()); + spinlock_t *lock; struct entry *entry, input; unsigned long flags; + if (likely(!active)) + return; + + lock = &per_cpu(lookup_lock, raw_smp_processor_id()); + input.timer = timer; input.start_func = startf; input.expire_func = timerf; |