aboutsummaryrefslogtreecommitdiffstats
path: root/include
diff options
context:
space:
mode:
authorThomas Gleixner <tglx@linutronix.de>2009-04-11 04:43:41 -0400
committerThomas Gleixner <tglx@linutronix.de>2009-05-15 09:32:45 -0400
commitdce48a84adf1806676319f6f480e30a6daa012f9 (patch)
tree79151f5d31d9c3dcdc723ab8877cb943b944890e /include
parent2ff799d3cff1ecb274049378b28120ee5c1c5e5f (diff)
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')
-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 b4c38bc8049c..6eb4892efe45 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -135,8 +135,8 @@ DECLARE_PER_CPU(unsigned long, process_counts);
135extern int nr_processes(void); 135extern int nr_processes(void);
136extern unsigned long nr_running(void); 136extern unsigned long nr_running(void);
137extern unsigned long nr_uninterruptible(void); 137extern unsigned long nr_uninterruptible(void);
138extern unsigned long nr_active(void);
139extern unsigned long nr_iowait(void); 138extern unsigned long nr_iowait(void);
139extern void calc_global_load(void);
140 140
141extern unsigned long get_parent_ip(unsigned long addr); 141extern unsigned long get_parent_ip(unsigned long addr);
142 142