diff options
| author | Jesse Barnes <jbarnes@engr.sgi.com> | 2004-11-10 21:29:32 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2004-11-10 21:29:32 -0800 |
| commit | a370025d1ed83b2b8202c4fefe4ea465bf22f10a (patch) | |
| tree | c18274d669421dc47eaedfbeab4a113f92172426 /include/linux | |
| parent | 6998fe2529d33f5441dbfed6e924c990d052c167 (diff) | |
[PATCH] remove contention on profile_lock
profile_hook unconditionally takes a read lock on profile_lock if kernel
profiling is enabled. The lock protects the profile_hook notifier chain
from being written while it's being called. The routine profile_hook is
called in a very hot path though: every timer tick on every CPU. As you
can imagine, on a large system, this makes the cacheline containing
profile_lock pretty hot. Since oprofile was the only user of the
profile_hook, I removed the notifier chain altogether in favor of a simple
function pointer with the help of John Levon. This removes all of the
contention in the hot path since the variable is very seldom written and
simplifies things a little to boot.
Acked-by: John Levon <levon@movementarian.org>
Signed-off-by: Jesse Barnes <jbarnes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/profile.h | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/include/linux/profile.h b/include/linux/profile.h index a22f4a15c981..026969a5595c 100644 --- a/include/linux/profile.h +++ b/include/linux/profile.h @@ -53,13 +53,13 @@ int task_handoff_unregister(struct notifier_block * n); int profile_event_register(enum profile_type, struct notifier_block * n); int profile_event_unregister(enum profile_type, struct notifier_block * n); -int register_profile_notifier(struct notifier_block * nb); -int unregister_profile_notifier(struct notifier_block * nb); +int register_timer_hook(int (*hook)(struct pt_regs *)); +void unregister_timer_hook(int (*hook)(struct pt_regs *)); -struct pt_regs; +/* Timer based profiling hook */ +extern int (*timer_hook)(struct pt_regs *); -/* profiling hook activated on each timer interrupt */ -void profile_hook(struct pt_regs * regs); +struct pt_regs; #else @@ -87,18 +87,16 @@ static inline int profile_event_unregister(enum profile_type t, struct notifier_ #define profile_handoff_task(a) (0) #define profile_munmap(a) do { } while (0) -static inline int register_profile_notifier(struct notifier_block * nb) +static inline int register_timer_hook(int (*hook)(struct pt_regs *)) { return -ENOSYS; } -static inline int unregister_profile_notifier(struct notifier_block * nb) +static inline void unregister_timer_hook(int (*hook)(struct pt_regs *)) { - return -ENOSYS; + return; } -#define profile_hook(regs) do { } while (0) - #endif /* CONFIG_PROFILING */ #endif /* __KERNEL__ */ |