Messages in this thread Patch in this message | | | Subject | [patch 6/7] sched: use rq->avg_event to resurrect nohz ratelimiting | From | Mike Galbraith <> | Date | Tue, 22 Nov 2011 15:24:53 +0100 |
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Entering nohz at high frequency eats cycles, ratelimit it just as we do idle_balance(), and for the same reason.
Signed-off-by: Mike Galbraith <efault@gmx.de>
--- include/linux/sched.h | 2 ++ kernel/sched/core.c | 7 +++++++ kernel/time/tick-sched.c | 2 +- 3 files changed, 10 insertions(+), 1 deletion(-)
Index: linux-3.0-tip/include/linux/sched.h =================================================================== --- linux-3.0-tip.orig/include/linux/sched.h +++ linux-3.0-tip/include/linux/sched.h @@ -1988,8 +1988,10 @@ static inline void idle_task_exit(void) #if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP) extern void wake_up_idle_cpu(int cpu); +extern int sched_needs_cpu(int cpu); #else static inline void wake_up_idle_cpu(int cpu) { } +static inline void sched_needs_cpu(int cpu) { } #endif extern unsigned int sysctl_sched_latency; Index: linux-3.0-tip/kernel/sched/core.c =================================================================== --- linux-3.0-tip.orig/kernel/sched/core.c +++ linux-3.0-tip/kernel/sched/core.c @@ -587,6 +587,13 @@ static inline bool got_nohz_idle_kick(vo return idle_cpu(smp_processor_id()) && this_rq()->nohz_balance_kick; } +#ifdef CONFIG_SMP +int sched_needs_cpu(int cpu) +{ + return cpu_rq(cpu)->avg_event < sysctl_sched_migration_cost; +} +#endif + #else /* CONFIG_NO_HZ */ static inline bool got_nohz_idle_kick(void) Index: linux-3.0-tip/kernel/time/tick-sched.c =================================================================== --- linux-3.0-tip.orig/kernel/time/tick-sched.c +++ linux-3.0-tip/kernel/time/tick-sched.c @@ -352,7 +352,7 @@ 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)) { + arch_needs_cpu(cpu) || sched_needs_cpu(cpu)) { next_jiffies = last_jiffies + 1; delta_jiffies = 1; } else {
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