From f03542a7019c600163ac4441d8a826c92c1bd510 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Thu, 26 Jul 2012 08:55:34 +0800 Subject: sched: recover SD_WAKE_AFFINE in select_task_rq_fair and code clean up Since power saving code was removed from sched now, the implement code is out of service in this function, and even pollute other logical. like, 'want_sd' never has chance to be set '0', that remove the effect of SD_WAKE_AFFINE here. So, clean up the obsolete code, includes SD_PREFER_LOCAL. Signed-off-by: Alex Shi Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/5028F431.6000306@intel.com Signed-off-by: Thomas Gleixner --- include/linux/sched.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index b8c86648a2f9..f3eebc121ebc 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -860,7 +860,6 @@ enum cpu_idle_type { #define SD_BALANCE_FORK 0x0008 /* Balance on fork, clone */ #define SD_BALANCE_WAKE 0x0010 /* Balance on wakeup */ #define SD_WAKE_AFFINE 0x0020 /* Wake task to waking CPU */ -#define SD_PREFER_LOCAL 0x0040 /* Prefer to keep tasks local to this domain */ #define SD_SHARE_CPUPOWER 0x0080 /* Domain members share cpu power */ #define SD_SHARE_PKG_RESOURCES 0x0200 /* Domain members share cpu pkg resources */ #define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */ -- cgit v1.2.3 From f3e947867478af9a12b9956bcd000ac7613a8a95 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 12 Sep 2012 11:22:00 +0200 Subject: sched: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW Now that the last architecture to use this has stopped doing so (ARM, thanks Catalin!) we can remove this complexity from the scheduler core. Signed-off-by: Peter Zijlstra Cc: Oleg Nesterov Cc: Catalin Marinas Link: http://lkml.kernel.org/n/tip-g9p2a1w81xxbrze25v9zpzbf@git.kernel.org Signed-off-by: Ingo Molnar --- Documentation/scheduler/sched-arch.txt | 10 --------- include/linux/sched.h | 5 ----- kernel/fork.c | 4 ---- kernel/sched/core.c | 40 +--------------------------------- kernel/sched/rt.c | 5 ----- kernel/sched/sched.h | 6 ----- 6 files changed, 1 insertion(+), 69 deletions(-) (limited to 'include/linux/sched.h') diff --git a/Documentation/scheduler/sched-arch.txt b/Documentation/scheduler/sched-arch.txt index 28aa1075e291..b1b8587b86f0 100644 --- a/Documentation/scheduler/sched-arch.txt +++ b/Documentation/scheduler/sched-arch.txt @@ -17,16 +17,6 @@ you must `#define __ARCH_WANT_UNLOCKED_CTXSW` in a header file Unlocked context switches introduce only a very minor performance penalty to the core scheduler implementation in the CONFIG_SMP case. -2. Interrupt status -By default, the switch_to arch function is called with interrupts -disabled. Interrupts may be enabled over the call if it is likely to -introduce a significant interrupt latency by adding the line -`#define __ARCH_WANT_INTERRUPTS_ON_CTXSW` in the same place as for -unlocked context switches. This define also implies -`__ARCH_WANT_UNLOCKED_CTXSW`. See arch/arm/include/asm/system.h for an -example. - - CPU idle ======== Your cpu_idle routines need to obey the following rules: diff --git a/include/linux/sched.h b/include/linux/sched.h index f3eebc121ebc..60e5e38eee2a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -678,11 +678,6 @@ struct signal_struct { * (notably. ptrace) */ }; -/* Context switch must be unlocked if interrupts are to be enabled */ -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW -# define __ARCH_WANT_UNLOCKED_CTXSW -#endif - /* * Bits in flags field of signal_struct. */ diff --git a/kernel/fork.c b/kernel/fork.c index 2c8857e12855..743d48f4d711 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1280,11 +1280,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, #endif #ifdef CONFIG_TRACE_IRQFLAGS p->irq_events = 0; -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW - p->hardirqs_enabled = 1; -#else p->hardirqs_enabled = 0; -#endif p->hardirq_enable_ip = 0; p->hardirq_enable_event = 0; p->hardirq_disable_ip = _THIS_IP_; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c46a011ce5db..8b51b2d9b1fd 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1361,25 +1361,6 @@ static void ttwu_queue_remote(struct task_struct *p, int cpu) smp_send_reschedule(cpu); } -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW -static int ttwu_activate_remote(struct task_struct *p, int wake_flags) -{ - struct rq *rq; - int ret = 0; - - rq = __task_rq_lock(p); - if (p->on_cpu) { - ttwu_activate(rq, p, ENQUEUE_WAKEUP); - ttwu_do_wakeup(rq, p, wake_flags); - ret = 1; - } - __task_rq_unlock(rq); - - return ret; - -} -#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ - bool cpus_share_cache(int this_cpu, int that_cpu) { return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); @@ -1440,21 +1421,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) * If the owning (remote) cpu is still in the middle of schedule() with * this task as prev, wait until its done referencing the task. */ - while (p->on_cpu) { -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW - /* - * In case the architecture enables interrupts in - * context_switch(), we cannot busy wait, since that - * would lead to deadlocks when an interrupt hits and - * tries to wake up @prev. So bail and do a complete - * remote wakeup. - */ - if (ttwu_activate_remote(p, wake_flags)) - goto stat; -#else + while (p->on_cpu) cpu_relax(); -#endif - } /* * Pairs with the smp_wmb() in finish_lock_switch(). */ @@ -1798,13 +1766,7 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev) prev_state = prev->state; account_switch_vtime(prev); finish_arch_switch(prev); -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW - local_irq_disable(); -#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ perf_event_task_sched_in(prev, current); -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW - local_irq_enable(); -#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ finish_lock_switch(rq, prev); finish_arch_post_lock_switch(); diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index e0b7ba9c040f..418feb01344e 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1632,11 +1632,6 @@ static int push_rt_task(struct rq *rq) if (!next_task) return 0; -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW - if (unlikely(task_running(rq, next_task))) - return 0; -#endif - retry: if (unlikely(next_task == rq->curr)) { WARN_ON(1); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 09871698e80c..7a7db09cfabc 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -737,11 +737,7 @@ static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) */ next->on_cpu = 1; #endif -#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW - raw_spin_unlock_irq(&rq->lock); -#else raw_spin_unlock(&rq->lock); -#endif } static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) @@ -755,9 +751,7 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) smp_wmb(); prev->on_cpu = 0; #endif -#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW local_irq_enable(); -#endif } #endif /* __ARCH_WANT_UNLOCKED_CTXSW */ -- cgit v1.2.3 From c1cc017c59c44d9ede7003631c43adc0cfdce2f9 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Mon, 10 Sep 2012 15:10:58 +0800 Subject: sched/nohz: Clean up select_nohz_load_balancer() There is no load_balancer to be selected now. It just sets the state of the nohz tick to stop. So rename the function, pass the 'cpu' as a parameter and then remove the useless call from tick_nohz_restart_sched_tick(). [ s/set_nohz_tick_stopped/nohz_balance_enter_idle/g s/clear_nohz_tick_stopped/nohz_balance_exit_idle/g ] Signed-off-by: Alex Shi Acked-by: Suresh Siddha Cc: Venkatesh Pallipadi Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1347261059-24747-1-git-send-email-alex.shi@intel.com Signed-off-by: Ingo Molnar --- include/linux/sched.h | 4 ++-- kernel/sched/fair.c | 25 ++++++++++--------------- kernel/time/tick-sched.c | 3 +-- 3 files changed, 13 insertions(+), 19 deletions(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 60e5e38eee2a..8c38df07ac3a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -273,11 +273,11 @@ extern void init_idle_bootup_task(struct task_struct *idle); extern int runqueue_is_locked(int cpu); #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ) -extern void select_nohz_load_balancer(int stop_tick); +extern void nohz_balance_enter_idle(int cpu); extern void set_cpu_sd_state_idle(void); extern int get_nohz_timer_target(void); #else -static inline void select_nohz_load_balancer(int stop_tick) { } +static inline void nohz_balance_enter_idle(int cpu) { } static inline void set_cpu_sd_state_idle(void) { } #endif diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 9ae3a5b68ba4..de596a2f626c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4603,7 +4603,7 @@ static void nohz_balancer_kick(int cpu) return; } -static inline void clear_nohz_tick_stopped(int cpu) +static inline void nohz_balance_exit_idle(int cpu) { if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); @@ -4643,28 +4643,23 @@ void set_cpu_sd_state_idle(void) } /* - * This routine will record that this cpu is going idle with tick stopped. + * This routine will record that the cpu is going idle with tick stopped. * This info will be used in performing idle load balancing in the future. */ -void select_nohz_load_balancer(int stop_tick) +void nohz_balance_enter_idle(int cpu) { - int cpu = smp_processor_id(); - /* * If this cpu is going down, then nothing needs to be done. */ if (!cpu_active(cpu)) return; - if (stop_tick) { - if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) - return; + if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) + return; - cpumask_set_cpu(cpu, nohz.idle_cpus_mask); - atomic_inc(&nohz.nr_cpus); - set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); - } - return; + cpumask_set_cpu(cpu, nohz.idle_cpus_mask); + atomic_inc(&nohz.nr_cpus); + set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); } static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb, @@ -4672,7 +4667,7 @@ static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb, { switch (action & ~CPU_TASKS_FROZEN) { case CPU_DYING: - clear_nohz_tick_stopped(smp_processor_id()); + nohz_balance_exit_idle(smp_processor_id()); return NOTIFY_OK; default: return NOTIFY_DONE; @@ -4833,7 +4828,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu) * busy tick after returning from idle, we will update the busy stats. */ set_cpu_sd_state_busy(); - clear_nohz_tick_stopped(cpu); + nohz_balance_exit_idle(cpu); /* * None are in tickless mode and hence no need for NOHZ idle load diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 3a9e5d5c1091..1a5ee90eea33 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -372,7 +372,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, * the scheduler tick in nohz_restart_sched_tick. */ if (!ts->tick_stopped) { - select_nohz_load_balancer(1); + nohz_balance_enter_idle(cpu); calc_load_enter_idle(); ts->last_tick = hrtimer_get_expires(&ts->sched_timer); @@ -569,7 +569,6 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now) { /* Update jiffies first */ - select_nohz_load_balancer(0); tick_do_update_jiffies64(now); update_cpu_load_nohz(); -- cgit v1.2.3