Messages in this thread Patch in this message | | | Date | Wed, 11 Aug 2010 17:06:13 -0700 | From | Greg KH <> | Subject | [58/67] sched: Revert nohz_ratelimit() for now |
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2.6.35-stable review patch. If anyone has any objections, please let us know.
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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
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>
--- include/linux/sched.h | 6 ------ kernel/sched.c | 10 ---------- kernel/time/tick-sched.c | 2 +- 3 files changed, 1 insertion(+), 17 deletions(-)
--- 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 /* --- 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) --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -325,7 +325,7 @@ void tick_nohz_stop_sched_tick(int inidl } 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 {
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