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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2010-07-09 15:12:27 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-13 13:31:02 -0700
commit1dc89aec877583e3e42421be77b063724a4bbb07 (patch)
tree572ff12657caa2a6072a0dd0b24f1b5971058485
parentb8253929a210627b924a8a33135042cd973a48ed (diff)
downloadlinux-2.6.34-ux500-1dc89aec877583e3e42421be77b063724a4bbb07.tar.gz
sched: Revert nohz_ratelimit() for now
commit 396e894d289d69bacf5acd983c97cd6e21a14c08 upstream. Norbert reported that nohz_ratelimit() causes his laptop to burn about 4W (40%) extra. For now back out the change and see if we can adjust the power management code to make better decisions. Reported-by: Norbert Preining <preining@logic.at> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Mike Galbraith <efault@gmx.de> Cc: Arjan van de Ven <arjan@infradead.org> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--include/linux/sched.h6
-rw-r--r--kernel/sched.c10
-rw-r--r--kernel/time/tick-sched.c2
3 files changed, 1 insertions, 17 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0478888c689..5ee397ee3bc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -274,17 +274,11 @@ extern cpumask_var_t nohz_cpu_mask;
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
extern int select_nohz_load_balancer(int cpu);
extern int get_nohz_load_balancer(void);
-extern int nohz_ratelimit(int cpu);
#else
static inline int select_nohz_load_balancer(int cpu)
{
return 0;
}
-
-static inline int nohz_ratelimit(int cpu)
-{
- return 0;
-}
#endif
/*
diff --git a/kernel/sched.c b/kernel/sched.c
index f52a8801b7a..63b4a14682f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1232,16 +1232,6 @@ void wake_up_idle_cpu(int cpu)
smp_send_reschedule(cpu);
}
-int nohz_ratelimit(int cpu)
-{
- struct rq *rq = cpu_rq(cpu);
- u64 diff = rq->clock - rq->nohz_stamp;
-
- rq->nohz_stamp = rq->clock;
-
- return diff < (NSEC_PER_SEC / HZ) >> 1;
-}
-
#endif /* CONFIG_NO_HZ */
static u64 sched_avg_period(void)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 813993b5fb6..f898af60817 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -325,7 +325,7 @@ void tick_nohz_stop_sched_tick(int inidle)
} while (read_seqretry(&xtime_lock, seq));
if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
- arch_needs_cpu(cpu) || nohz_ratelimit(cpu)) {
+ arch_needs_cpu(cpu)) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {