diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2009-06-23 17:38:15 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-06-24 11:15:09 +0200 |
| commit | 507e123151149e578c9aae33eb876c49824da5f8 (patch) | |
| tree | 10b4c36a278553ed3814c0643442e7210a7a1a15 /include/linux/hrtimer.h | |
| parent | bfdb4d9f0f611687d71cf6a460efc9e755f4a462 (diff) | |
timer stats: Optimize by adding quick check to avoid function calls
When the kernel is configured with CONFIG_TIMER_STATS but timer
stats are runtime disabled we still get calls to
__timer_stats_timer_set_start_info which initializes some
fields in the corresponding struct timer_list.
So add some quick checks in the the timer stats setup functions
to avoid function calls to __timer_stats_timer_set_start_info
when timer stats are disabled.
In an artificial workload that does nothing but playing ping
pong with a single tcp packet via loopback this decreases cpu
consumption by 1 - 1.5%.
This is part of a modified function trace output on SLES11:
perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv
perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer
perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer
perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer
perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer
perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mustafa Mesanovic <mustafa.mesanovic@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <20090623153811.GA4641@osiris.boeblingen.de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/hrtimer.h')
| -rw-r--r-- | include/linux/hrtimer.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 7400900de94..54648e625ef 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -21,6 +21,7 @@ #include <linux/list.h> #include <linux/wait.h> #include <linux/percpu.h> +#include <linux/timer.h> struct hrtimer_clock_base; @@ -447,6 +448,8 @@ extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf, static inline void timer_stats_account_hrtimer(struct hrtimer *timer) { + if (likely(!timer->start_pid)) + return; timer_stats_update_stats(timer, timer->start_pid, timer->start_site, timer->function, timer->start_comm, 0); } @@ -456,6 +459,8 @@ extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer, static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer) { + if (likely(!timer_stats_active)) + return; __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0)); } |