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authorThomas Gleixner <tglx@linutronix.de>2009-04-11 10:43:41 +0200
committerThomas Gleixner <tglx@linutronix.de>2009-05-15 15:32:45 +0200
commitdce48a84adf1806676319f6f480e30a6daa012f9 (patch)
tree79151f5d31d9c3dcdc723ab8877cb943b944890e /include/linux/sched.h
parent2ff799d3cff1ecb274049378b28120ee5c1c5e5f (diff)
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sched, timers: move calc_load() to scheduler
Dimitri Sivanich noticed that xtime_lock is held write locked across calc_load() which iterates over all online CPUs. That can cause long latencies for xtime_lock readers on large SMP systems. The load average calculation is an rough estimate anyway so there is no real need to protect the readers vs. the update. It's not a problem when the avenrun array is updated while a reader copies the values. Instead of iterating over all online CPUs let the scheduler_tick code update the number of active tasks shortly before the avenrun update happens. The avenrun update itself is handled by the CPU which calls do_timer(). [ Impact: reduce xtime_lock write locked section ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org>
Diffstat (limited to 'include/linux/sched.h')
-rw-r--r--include/linux/sched.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index b4c38bc..6eb4892 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -135,8 +135,8 @@ DECLARE_PER_CPU(unsigned long, process_counts);
extern int nr_processes(void);
extern unsigned long nr_running(void);
extern unsigned long nr_uninterruptible(void);
-extern unsigned long nr_active(void);
extern unsigned long nr_iowait(void);
+extern void calc_global_load(void);
extern unsigned long get_parent_ip(unsigned long addr);
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