Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751218AbWCUXyX (ORCPT ); Tue, 21 Mar 2006 18:54:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751442AbWCUXyW (ORCPT ); Tue, 21 Mar 2006 18:54:22 -0500 Received: from mail04.syd.optusnet.com.au ([211.29.132.185]:62926 "EHLO mail04.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S1751218AbWCUXyV (ORCPT ); Tue, 21 Mar 2006 18:54:21 -0500 From: Con Kolivas To: linux-kernel@vger.kernel.org Subject: [PATCH] Staircase cpu scheduler v14.2 Date: Wed, 22 Mar 2006 10:54:55 +1100 User-Agent: KMail/1.8.3 Cc: ck@vds.kolivas.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200603221054.55686.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 49261 Lines: 1647 Just as a reminder, the staircase cpu scheduler is still in active development. While included in the -ck patchset, the standalone patch can be downloaded here: http://ck.kolivas.org/patches/staircase/ Here is the current base staircase patch for 2.6.16 Cheers, Con --- fs/proc/array.c | 4 include/linux/sched.h | 12 kernel/exit.c | 1 kernel/sched.c | 966 +++++++++++++++++--------------------------------- 4 files changed, 349 insertions(+), 634 deletions(-) Index: linux-2.6.16-staircase/fs/proc/array.c =================================================================== --- linux-2.6.16-staircase.orig/fs/proc/array.c 2006-03-21 15:09:37.000000000 +1100 +++ linux-2.6.16-staircase/fs/proc/array.c 2006-03-22 08:52:26.000000000 +1100 @@ -165,7 +165,7 @@ static inline char * task_state(struct t read_lock(&tasklist_lock); buffer += sprintf(buffer, "State:\t%s\n" - "SleepAVG:\t%lu%%\n" + "Bonus:\t%d\n" "Tgid:\t%d\n" "Pid:\t%d\n" "PPid:\t%d\n" @@ -173,7 +173,7 @@ static inline char * task_state(struct t "Uid:\t%d\t%d\t%d\t%d\n" "Gid:\t%d\t%d\t%d\t%d\n", get_task_state(p), - (p->sleep_avg/1024)*100/(1020000000/1024), + p->bonus, p->tgid, p->pid, pid_alive(p) ? p->group_leader->real_parent->tgid : 0, pid_alive(p) && p->ptrace ? p->parent->pid : 0, Index: linux-2.6.16-staircase/include/linux/sched.h =================================================================== --- linux-2.6.16-staircase.orig/include/linux/sched.h 2006-03-21 15:09:38.000000000 +1100 +++ linux-2.6.16-staircase/include/linux/sched.h 2006-03-22 09:14:18.000000000 +1100 @@ -521,7 +521,6 @@ extern struct user_struct *find_user(uid extern struct user_struct root_user; #define INIT_USER (&root_user) -typedef struct prio_array prio_array_t; struct backing_dev_info; struct reclaim_state; @@ -703,18 +702,17 @@ struct task_struct { #endif int prio, static_prio; struct list_head run_list; - prio_array_t *array; unsigned short ioprio; - unsigned long sleep_avg; - unsigned long long timestamp, last_ran; + unsigned long long timestamp; + unsigned long runtime, totalrun, ns_debit; + unsigned int bonus; + unsigned int slice, time_slice; unsigned long long sched_time; /* sched_clock time spent running */ - int activated; unsigned long policy; cpumask_t cpus_allowed; - unsigned int time_slice, first_time_slice; #ifdef CONFIG_SCHEDSTATS struct sched_info sched_info; @@ -928,6 +926,7 @@ static inline void put_task_struct(struc #define PF_BORROWED_MM 0x00400000 /* I am a kthread doing use_mm */ #define PF_RANDOMIZE 0x00800000 /* randomize virtual address space */ #define PF_SWAPWRITE 0x01000000 /* Allowed to write to swap */ +#define PF_NONSLEEP 0x02000000 /* Waiting on in kernel activity */ /* * Only the _current_ task can read/write to tsk->flags, but other @@ -1049,7 +1048,6 @@ extern void FASTCALL(wake_up_new_task(st static inline void kick_process(struct task_struct *tsk) { } #endif extern void FASTCALL(sched_fork(task_t * p, int clone_flags)); -extern void FASTCALL(sched_exit(task_t * p)); extern int in_group_p(gid_t); extern int in_egroup_p(gid_t); Index: linux-2.6.16-staircase/kernel/exit.c =================================================================== --- linux-2.6.16-staircase.orig/kernel/exit.c 2006-03-21 15:09:38.000000000 +1100 +++ linux-2.6.16-staircase/kernel/exit.c 2006-03-22 08:52:26.000000000 +1100 @@ -102,7 +102,6 @@ repeat: zap_leader = (leader->exit_signal == -1); } - sched_exit(p); write_unlock_irq(&tasklist_lock); spin_unlock(&p->proc_lock); proc_pid_flush(proc_dentry); Index: linux-2.6.16-staircase/kernel/sched.c =================================================================== --- linux-2.6.16-staircase.orig/kernel/sched.c 2006-03-21 15:09:38.000000000 +1100 +++ linux-2.6.16-staircase/kernel/sched.c 2006-03-22 10:41:38.000000000 +1100 @@ -16,6 +16,9 @@ * by Davide Libenzi, preemptible kernel bits by Robert Love. * 2003-09-03 Interactivity tuning by Con Kolivas. * 2004-04-02 Scheduler domains code by Nick Piggin + * 2006-03-16 New staircase scheduling policy by Con Kolivas with help + * from William Lee Irwin III, Zwane Mwaikambo & Peter Williams. + * Staircase v14.2 */ #include @@ -76,122 +79,26 @@ */ #define NS_TO_JIFFIES(TIME) ((TIME) / (1000000000 / HZ)) #define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ)) - -/* - * These are the 'tuning knobs' of the scheduler: - * - * Minimum timeslice is 5 msecs (or 1 jiffy, whichever is larger), - * default timeslice is 100 msecs, maximum timeslice is 800 msecs. - * Timeslices get refilled after they expire. - */ -#define MIN_TIMESLICE max(5 * HZ / 1000, 1) -#define DEF_TIMESLICE (100 * HZ / 1000) -#define ON_RUNQUEUE_WEIGHT 30 -#define CHILD_PENALTY 95 -#define PARENT_PENALTY 100 -#define EXIT_WEIGHT 3 -#define PRIO_BONUS_RATIO 25 -#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100) -#define INTERACTIVE_DELTA 2 -#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS) -#define STARVATION_LIMIT (MAX_SLEEP_AVG) -#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG)) - -/* - * If a task is 'interactive' then we reinsert it in the active - * array after it has expired its current timeslice. (it will not - * continue to run immediately, it will still roundrobin with - * other interactive tasks.) - * - * This part scales the interactivity limit depending on niceness. - * - * We scale it linearly, offset by the INTERACTIVE_DELTA delta. - * Here are a few examples of different nice levels: - * - * TASK_INTERACTIVE(-20): [1,1,1,1,1,1,1,1,1,0,0] - * TASK_INTERACTIVE(-10): [1,1,1,1,1,1,1,0,0,0,0] - * TASK_INTERACTIVE( 0): [1,1,1,1,0,0,0,0,0,0,0] - * TASK_INTERACTIVE( 10): [1,1,0,0,0,0,0,0,0,0,0] - * TASK_INTERACTIVE( 19): [0,0,0,0,0,0,0,0,0,0,0] - * - * (the X axis represents the possible -5 ... 0 ... +5 dynamic - * priority range a task can explore, a value of '1' means the - * task is rated interactive.) - * - * Ie. nice +19 tasks can never get 'interactive' enough to be - * reinserted into the active array. And only heavily CPU-hog nice -20 - * tasks will be expired. Default nice 0 tasks are somewhere between, - * it takes some effort for them to get interactive, but it's not - * too hard. - */ - -#define CURRENT_BONUS(p) \ - (NS_TO_JIFFIES((p)->sleep_avg) * MAX_BONUS / \ - MAX_SLEEP_AVG) - -#define GRANULARITY (10 * HZ / 1000 ? : 1) - -#ifdef CONFIG_SMP -#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ - (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1)) * \ - num_online_cpus()) -#else -#define TIMESLICE_GRANULARITY(p) (GRANULARITY * \ - (1 << (((MAX_BONUS - CURRENT_BONUS(p)) ? : 1) - 1))) -#endif - -#define SCALE(v1,v1_max,v2_max) \ - (v1) * (v2_max) / (v1_max) - -#define DELTA(p) \ - (SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA) - -#define TASK_INTERACTIVE(p) \ - ((p)->prio <= (p)->static_prio - DELTA(p)) - -#define INTERACTIVE_SLEEP(p) \ - (JIFFIES_TO_NS(MAX_SLEEP_AVG * \ - (MAX_BONUS / 2 + DELTA((p)) + 1) / MAX_BONUS - 1)) +#define NSJIFFY (1000000000 / HZ) /* One jiffy in ns */ #define TASK_PREEMPTS_CURR(p, rq) \ ((p)->prio < (rq)->curr->prio) /* - * task_timeslice() scales user-nice values [ -20 ... 0 ... 19 ] - * to time slice values: [800ms ... 100ms ... 5ms] - * - * The higher a thread's priority, the bigger timeslices - * it gets during one round of execution. But even the lowest - * priority thread gets MIN_TIMESLICE worth of execution time. + * This is the time all tasks within the same priority round robin. + * Set to a minimum of 6ms. */ +#define RR_INTERVAL ((6 * HZ / 1001) + 1) +#define DEF_TIMESLICE (RR_INTERVAL * 19) -#define SCALE_PRIO(x, prio) \ - max(x * (MAX_PRIO - prio) / (MAX_USER_PRIO/2), MIN_TIMESLICE) - -static unsigned int task_timeslice(task_t *p) -{ - if (p->static_prio < NICE_TO_PRIO(0)) - return SCALE_PRIO(DEF_TIMESLICE*4, p->static_prio); - else - return SCALE_PRIO(DEF_TIMESLICE, p->static_prio); -} -#define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran) \ +#define task_hot(p, now, sd) ((long long) ((now) - (p)->timestamp) \ < (long long) (sd)->cache_hot_time) /* * These are the runqueue data structures: */ - -#define BITMAP_SIZE ((((MAX_PRIO+1+7)/8)+sizeof(long)-1)/sizeof(long)) - typedef struct runqueue runqueue_t; -struct prio_array { - unsigned int nr_active; - unsigned long bitmap[BITMAP_SIZE]; - struct list_head queue[MAX_PRIO]; -}; - /* * This is the main, per-CPU runqueue data structure. * @@ -220,12 +127,11 @@ struct runqueue { */ unsigned long nr_uninterruptible; - unsigned long expired_timestamp; unsigned long long timestamp_last_tick; task_t *curr, *idle; struct mm_struct *prev_mm; - prio_array_t *active, *expired, arrays[2]; - int best_expired_prio; + unsigned long bitmap[BITS_TO_LONGS(MAX_PRIO + 1)]; + struct list_head queue[MAX_PRIO]; atomic_t nr_iowait; #ifdef CONFIG_SMP @@ -489,13 +395,7 @@ static inline runqueue_t *this_rq_lock(v #ifdef CONFIG_SCHEDSTATS /* - * Called when a process is dequeued from the active array and given - * the cpu. We should note that with the exception of interactive - * tasks, the expired queue will become the active queue after the active - * queue is empty, without explicitly dequeuing and requeuing tasks in the - * expired queue. (Interactive tasks may be requeued directly to the - * active queue, thus delaying tasks in the expired queue from running; - * see scheduler_tick()). + * Called when a process is dequeued and given the cpu. * * This function is only called from sched_info_arrive(), rather than * dequeue_task(). Even though a task may be queued and dequeued multiple @@ -533,13 +433,11 @@ static void sched_info_arrive(task_t *t) } /* - * Called when a process is queued into either the active or expired - * array. The time is noted and later used to determine how long we - * had to wait for us to reach the cpu. Since the expired queue will - * become the active queue after active queue is empty, without dequeuing - * and requeuing any tasks, we are interested in queuing to either. It - * is unusual but not impossible for tasks to be dequeued and immediately - * requeued in the same or another array: this can happen in sched_yield(), + * Called when a process is queued + * The time is noted and later used to determine how long we had to wait for + * us to reach the cpu. + * It is unusual but not impossible for tasks to be dequeued and immediately + * requeued: this can happen in sched_yield(), * set_user_nice(), and even load_balance() as it moves tasks from runqueue * to runqueue. * @@ -594,79 +492,72 @@ static inline void sched_info_switch(tas #endif /* CONFIG_SCHEDSTATS */ /* - * Adding/removing a task to/from a priority array: + * Get nanosecond clock difference without overflowing unsigned long. */ -static void dequeue_task(struct task_struct *p, prio_array_t *array) +static unsigned long ns_diff(const unsigned long long v1, + const unsigned long long v2) { - array->nr_active--; - list_del(&p->run_list); - if (list_empty(array->queue + p->prio)) - __clear_bit(p->prio, array->bitmap); + unsigned long long vdiff; + if (likely(v1 > v2)) { + vdiff = v1 - v2; +#if BITS_PER_LONG < 64 + if (vdiff > (1 << 31)) + vdiff = 1 << 31; +#endif + } else { + /* + * Rarely the clock appears to go backwards. There should + * always be a positive difference so return 1. + */ + vdiff = 1; + } + return (unsigned long)vdiff; } -static void enqueue_task(struct task_struct *p, prio_array_t *array) +static inline int task_queued(const task_t *task) { - sched_info_queued(p); - list_add_tail(&p->run_list, array->queue + p->prio); - __set_bit(p->prio, array->bitmap); - array->nr_active++; - p->array = array; + return !list_empty(&task->run_list); } /* - * Put task to the end of the run list without the overhead of dequeue - * followed by enqueue. + * Adding/removing a task to/from a runqueue: */ -static void requeue_task(struct task_struct *p, prio_array_t *array) +static void fastcall dequeue_task(task_t *p, runqueue_t *rq) { - list_move_tail(&p->run_list, array->queue + p->prio); + list_del_init(&p->run_list); + if (list_empty(rq->queue + p->prio)) + __clear_bit(p->prio, rq->bitmap); + p->ns_debit = 0; } -static inline void enqueue_task_head(struct task_struct *p, prio_array_t *array) +static void fastcall enqueue_task(task_t *p, runqueue_t *rq) { - list_add(&p->run_list, array->queue + p->prio); - __set_bit(p->prio, array->bitmap); - array->nr_active++; - p->array = array; + list_add_tail(&p->run_list, rq->queue + p->prio); + __set_bit(p->prio, rq->bitmap); } /* - * effective_prio - return the priority that is based on the static - * priority but is modified by bonuses/penalties. - * - * We scale the actual sleep average [0 .... MAX_SLEEP_AVG] - * into the -5 ... 0 ... +5 bonus/penalty range. - * - * We use 25% of the full 0...39 priority range so that: - * - * 1) nice +19 interactive tasks do not preempt nice 0 CPU hogs. - * 2) nice -20 CPU hogs do not get preempted by nice 0 tasks. - * - * Both properties are important to certain workloads. + * Put task to the end of the run list without the overhead of dequeue + * followed by enqueue. */ -static int effective_prio(task_t *p) +static void requeue_task(task_t *p, runqueue_t *rq) { - int bonus, prio; - - if (rt_task(p)) - return p->prio; - - bonus = CURRENT_BONUS(p) - MAX_BONUS / 2; + list_move_tail(&p->run_list, rq->queue + p->prio); +} - prio = p->static_prio - bonus; - if (prio < MAX_RT_PRIO) - prio = MAX_RT_PRIO; - if (prio > MAX_PRIO-1) - prio = MAX_PRIO-1; - return prio; +static inline void enqueue_task_head(task_t *p, runqueue_t *rq) +{ + list_add(&p->run_list, rq->queue + p->prio); + __set_bit(p->prio, rq->bitmap); } + /* * __activate_task - move a task to the runqueue. */ static inline void __activate_task(task_t *p, runqueue_t *rq) { - enqueue_task(p, rq->active); + enqueue_task(p, rq); rq->nr_running++; } @@ -675,87 +566,164 @@ static inline void __activate_task(task_ */ static inline void __activate_idle_task(task_t *p, runqueue_t *rq) { - enqueue_task_head(p, rq->active); + enqueue_task_head(p, rq); rq->nr_running++; } -static int recalc_task_prio(task_t *p, unsigned long long now) +/* + * Bonus - How much higher than its base priority an interactive task can run. + */ +static inline unsigned int bonus(const task_t *p) { - /* Caller must always ensure 'now >= p->timestamp' */ - unsigned long long __sleep_time = now - p->timestamp; - unsigned long sleep_time; - - if (unlikely(p->policy == SCHED_BATCH)) - sleep_time = 0; - else { - if (__sleep_time > NS_MAX_SLEEP_AVG) - sleep_time = NS_MAX_SLEEP_AVG; - else - sleep_time = (unsigned long)__sleep_time; - } + return TASK_USER_PRIO(p); +} - if (likely(sleep_time > 0)) { - /* - * User tasks that sleep a long time are categorised as - * idle and will get just interactive status to stay active & - * prevent them suddenly becoming cpu hogs and starving - * other processes. - */ - if (p->mm && p->activated != -1 && - sleep_time > INTERACTIVE_SLEEP(p)) { - p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG - - DEF_TIMESLICE); - } else { - /* - * The lower the sleep avg a task has the more - * rapidly it will rise with sleep time. - */ - sleep_time *= (MAX_BONUS - CURRENT_BONUS(p)) ? : 1; +static unsigned int fastcall rr_interval(const task_t *p) +{ + int nice = TASK_NICE(p); - /* - * Tasks waking from uninterruptible sleep are - * limited in their sleep_avg rise as they - * are likely to be waiting on I/O - */ - if (p->activated == -1 && p->mm) { - if (p->sleep_avg >= INTERACTIVE_SLEEP(p)) - sleep_time = 0; - else if (p->sleep_avg + sleep_time >= - INTERACTIVE_SLEEP(p)) { - p->sleep_avg = INTERACTIVE_SLEEP(p); - sleep_time = 0; - } - } + if (nice < 0 && !rt_task(p)) + return RR_INTERVAL * (20 - nice) / 20; + return RR_INTERVAL; +} - /* - * This code gives a bonus to interactive tasks. - * - * The boost works by updating the 'average sleep time' - * value here, based on ->timestamp. The more time a - * task spends sleeping, the higher the average gets - - * and the higher the priority boost gets as well. - */ - p->sleep_avg += sleep_time; +/* + * slice - the duration a task runs before getting requeued at its best + * priority and has its bonus decremented. + */ +static unsigned int fastcall slice(const task_t *p) +{ + unsigned int slice, rr; - if (p->sleep_avg > NS_MAX_SLEEP_AVG) - p->sleep_avg = NS_MAX_SLEEP_AVG; - } + slice = rr = rr_interval(p); + if (likely(!rt_task(p))) + slice += (39 - TASK_USER_PRIO(p)) * rr; + return slice; +} + +/* + * We increase our bonus by sleeping more than the time we ran. + * The ratio of sleep to run gives us the cpu% that we last ran and determines + * the maximum bonus we can acquire. + */ +static void fastcall inc_bonus(task_t *p, const unsigned long totalrun, + const unsigned long sleep) +{ + unsigned int best_bonus; + + best_bonus = sleep / (totalrun + 1); + if (p->bonus >= best_bonus) + return; + + p->bonus++; + best_bonus = bonus(p); + if (p->bonus > best_bonus) + p->bonus = best_bonus; +} + +static void dec_bonus(task_t *p) +{ + if (p->bonus) + p->bonus--; +} + +/* + * effective_prio - dynamic priority dependent on bonus. + * The priority normally decreases by one each RR_INTERVAL. + * As the bonus increases the initial priority starts at a higher "stair" or + * priority for longer. + */ +static int effective_prio(const task_t *p) +{ + int prio; + unsigned int full_slice, used_slice = 0; + unsigned int best_bonus, rr; + + if (rt_task(p)) + return p->prio; + + full_slice = slice(p); + if (full_slice > p->slice) + used_slice = full_slice - p->slice; + + best_bonus = bonus(p); + prio = MAX_RT_PRIO + best_bonus; + if (likely(p->policy != SCHED_BATCH)) + prio -= p->bonus; + + rr = rr_interval(p); + prio += used_slice / rr; + if (prio > MAX_PRIO - 1) + prio = MAX_PRIO - 1; + return prio; +} + +static inline void continue_slice(task_t *p) +{ + unsigned long total_run = NS_TO_JIFFIES(p->totalrun); + + if (total_run >= p->slice) { + p->totalrun -= JIFFIES_TO_NS(p->slice); + dec_bonus(p); + } else { + unsigned int remainder; + + p->slice -= total_run; + remainder = p->slice % rr_interval(p); + if (remainder) + p->time_slice = remainder; } +} + +/* + * recalc_task_prio - this checks for tasks that run ultra short timeslices + * or have just forked a thread/process and make them continue their old + * slice instead of starting a new one at high priority. + */ +static inline void recalc_task_prio(task_t *p, const unsigned long long now) +{ + unsigned long sleep_time = ns_diff(now, p->timestamp); - return effective_prio(p); + /* + * Add the total for this last scheduled run (p->runtime) to the + * running total so far used (p->totalrun). + */ + p->totalrun += p->runtime; + + /* + * If we sleep longer than our running total and have not set the + * PF_NONSLEEP flag we gain a bonus. + */ + if (sleep_time >= p->totalrun && !(p->flags & PF_NONSLEEP)) { + inc_bonus(p, p->totalrun, sleep_time); + p->totalrun = 0; + return; + } + + /* + * If we have not set the PF_NONSLEEP flag we elevate priority by the + * amount of time we slept. + */ + if (p->flags & PF_NONSLEEP) + p->flags &= ~PF_NONSLEEP; + else + p->totalrun -= sleep_time; + + continue_slice(p); } + /* * activate_task - move a task to the runqueue and do priority recalculation * * Update all the scheduling statistics stuff. (sleep average * calculation, priority modifiers, etc.) */ -static void activate_task(task_t *p, runqueue_t *rq, int local) +static void activate_task(task_t *p, runqueue_t *rq, const int local) { - unsigned long long now; + unsigned long long now = sched_clock(); + unsigned long rr = rr_interval(p); - now = sched_clock(); #ifdef CONFIG_SMP if (!local) { /* Compensate for drifting sched_clock */ @@ -764,45 +732,24 @@ static void activate_task(task_t *p, run + rq->timestamp_last_tick; } #endif - - if (!rt_task(p)) - p->prio = recalc_task_prio(p, now); - - /* - * This checks to make sure it's not an uninterruptible task - * that is now waking up. - */ - if (!p->activated) { - /* - * Tasks which were woken up by interrupts (ie. hw events) - * are most likely of interactive nature. So we give them - * the credit of extending their sleep time to the period - * of time they spend on the runqueue, waiting for execution - * on a CPU, first time around: - */ - if (in_interrupt()) - p->activated = 2; - else { - /* - * Normal first-time wakeups get a credit too for - * on-runqueue time, but it will be weighted down: - */ - p->activated = 1; - } + p->slice = slice(p); + p->time_slice = p->slice % rr ? : rr; + if (!rt_task(p)) { + recalc_task_prio(p, now); + p->flags &= ~PF_NONSLEEP; + p->prio = effective_prio(p); } p->timestamp = now; - __activate_task(p, rq); } /* * deactivate_task - remove a task from the runqueue. */ -static void deactivate_task(struct task_struct *p, runqueue_t *rq) +static void fastcall deactivate_task(task_t *p, runqueue_t *rq) { rq->nr_running--; - dequeue_task(p, p->array); - p->array = NULL; + dequeue_task(p, rq); } /* @@ -872,7 +819,7 @@ static int migrate_task(task_t *p, int d * If the task is not on a runqueue (and not running), then * it is sufficient to simply update the task's cpu field. */ - if (!p->array && !task_running(rq, p)) { + if (!task_queued(p) && !task_running(rq, p)) { set_task_cpu(p, dest_cpu); return 0; } @@ -902,7 +849,7 @@ void wait_task_inactive(task_t *p) repeat: rq = task_rq_lock(p, &flags); /* Must be off runqueue entirely, not preempted. */ - if (unlikely(p->array || task_running(rq, p))) { + if (unlikely(task_queued(p) || task_running(rq, p))) { /* If it's preempted, we yield. It could be a while. */ preempted = !task_running(rq, p); task_rq_unlock(rq, &flags); @@ -1140,6 +1087,15 @@ static inline int wake_idle(int cpu, tas } #endif +/* + * Check to see if p preempts rq->curr and resched if it does. + */ +static inline void preempt(const task_t *p, runqueue_t *rq) +{ + if (p->prio < rq->curr->prio) + resched_task(rq->curr); +} + /*** * try_to_wake_up - wake up a thread * @p: the to-be-woken-up thread @@ -1171,7 +1127,7 @@ static int try_to_wake_up(task_t *p, uns if (!(old_state & state)) goto out; - if (p->array) + if (task_queued(p)) goto out_running; cpu = task_cpu(p); @@ -1260,7 +1216,7 @@ out_set_cpu: old_state = p->state; if (!(old_state & state)) goto out; - if (p->array) + if (task_queued(p)) goto out_running; this_cpu = smp_processor_id(); @@ -1269,26 +1225,10 @@ out_set_cpu: out_activate: #endif /* CONFIG_SMP */ - if (old_state == TASK_UNINTERRUPTIBLE) { + if (old_state == TASK_UNINTERRUPTIBLE) rq->nr_uninterruptible--; - /* - * Tasks on involuntary sleep don't earn - * sleep_avg beyond just interactive state. - */ - p->activated = -1; - } /* - * Tasks that have marked their sleep as noninteractive get - * woken up without updating their sleep average. (i.e. their - * sleep is handled in a priority-neutral manner, no priority - * boost and no penalty.) - */ - if (old_state & TASK_NONINTERACTIVE) - __activate_task(p, rq); - else - activate_task(p, rq, cpu == this_cpu); - /* * Sync wakeups (i.e. those types of wakeups where the waker * has indicated that it will leave the CPU in short order) * don't trigger a preemption, if the woken up task will run on @@ -1296,10 +1236,9 @@ out_activate: * the waker guarantees that the freshly woken up task is going * to be considered on this CPU.) */ - if (!sync || cpu != this_cpu) { - if (TASK_PREEMPTS_CURR(p, rq)) - resched_task(rq->curr); - } + activate_task(p, rq, cpu == this_cpu); + if (!sync || cpu != this_cpu) + preempt(p, rq); success = 1; out_running: @@ -1344,7 +1283,6 @@ void fastcall sched_fork(task_t *p, int */ p->state = TASK_RUNNING; INIT_LIST_HEAD(&p->run_list); - p->array = NULL; #ifdef CONFIG_SCHEDSTATS memset(&p->sched_info, 0, sizeof(p->sched_info)); #endif @@ -1355,30 +1293,6 @@ void fastcall sched_fork(task_t *p, int /* Want to start with kernel preemption disabled. */ task_thread_info(p)->preempt_count = 1; #endif - /* - * Share the timeslice between parent and child, thus the - * total amount of pending timeslices in the system doesn't change, - * resulting in more scheduling fairness. - */ - local_irq_disable(); - p->time_slice = (current->time_slice + 1) >> 1; - /* - * The remainder of the first timeslice might be recovered by - * the parent if the child exits early enough. - */ - p->first_time_slice = 1; - current->time_slice >>= 1; - p->timestamp = sched_clock(); - if (unlikely(!current->time_slice)) { - /* - * This case is rare, it happens when the parent has only - * a single jiffy left from its timeslice. Taking the - * runqueue lock is not a problem. - */ - current->time_slice = 1; - scheduler_tick(); - } - local_irq_enable(); put_cpu(); } @@ -1401,36 +1315,20 @@ void fastcall wake_up_new_task(task_t *p cpu = task_cpu(p); /* - * We decrease the sleep average of forking parents - * and children as well, to keep max-interactive tasks - * from forking tasks that are max-interactive. The parent - * (current) is done further down, under its lock. + * Forked process gets no bonus to prevent fork bombs. */ - p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) * - CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS); - - p->prio = effective_prio(p); + p->bonus = 0; if (likely(cpu == this_cpu)) { - if (!(clone_flags & CLONE_VM)) { + current->flags |= PF_NONSLEEP; + activate_task(p, rq, 1); + if (!(clone_flags & CLONE_VM)) /* * The VM isn't cloned, so we're in a good position to * do child-runs-first in anticipation of an exec. This * usually avoids a lot of COW overhead. */ - if (unlikely(!current->array)) - __activate_task(p, rq); - else { - p->prio = current->prio; - list_add_tail(&p->run_list, ¤t->run_list); - p->array = current->array; - p->array->nr_active++; - rq->nr_running++; - } set_need_resched(); - } else - /* Run child last */ - __activate_task(p, rq); /* * We skip the following code due to cpu == this_cpu * @@ -1447,53 +1345,20 @@ void fastcall wake_up_new_task(task_t *p */ p->timestamp = (p->timestamp - this_rq->timestamp_last_tick) + rq->timestamp_last_tick; - __activate_task(p, rq); - if (TASK_PREEMPTS_CURR(p, rq)) - resched_task(rq->curr); + activate_task(p, rq, 0); + preempt(p, rq); /* * Parent and child are on different CPUs, now get the - * parent runqueue to update the parent's ->sleep_avg: + * parent runqueue to update the parent's ->flags: */ task_rq_unlock(rq, &flags); this_rq = task_rq_lock(current, &flags); + current->flags |= PF_NONSLEEP; } - current->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(current) * - PARENT_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS); task_rq_unlock(this_rq, &flags); } -/* - * Potentially available exiting-child timeslices are - * retrieved here - this way the parent does not get - * penalized for creating too many threads. - * - * (this cannot be used to 'generate' timeslices - * artificially, because any timeslice recovered here - * was given away by the parent in the first place.) - */ -void fastcall sched_exit(task_t *p) -{ - unsigned long flags; - runqueue_t *rq; - - /* - * If the child was a (relative-) CPU hog then decrease - * the sleep_avg of the parent as well. - */ - rq = task_rq_lock(p->parent, &flags); - if (p->first_time_slice && task_cpu(p) == task_cpu(p->parent)) { - p->parent->time_slice += p->time_slice; - if (unlikely(p->parent->time_slice > task_timeslice(p))) - p->parent->time_slice = task_timeslice(p); - } - if (p->sleep_avg < p->parent->sleep_avg) - p->parent->sleep_avg = p->parent->sleep_avg / - (EXIT_WEIGHT + 1) * EXIT_WEIGHT + p->sleep_avg / - (EXIT_WEIGHT + 1); - task_rq_unlock(rq, &flags); -} - /** * prepare_task_switch - prepare to switch tasks * @rq: the runqueue preparing to switch @@ -1765,23 +1630,21 @@ void sched_exec(void) * pull_task - move a task from a remote runqueue to the local runqueue. * Both runqueues must be locked. */ -static -void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p, - runqueue_t *this_rq, prio_array_t *this_array, int this_cpu) +static void pull_task(runqueue_t *src_rq, task_t *p, runqueue_t *this_rq, + const int this_cpu) { - dequeue_task(p, src_array); + dequeue_task(p, src_rq); src_rq->nr_running--; set_task_cpu(p, this_cpu); this_rq->nr_running++; - enqueue_task(p, this_array); + enqueue_task(p, this_rq); p->timestamp = (p->timestamp - src_rq->timestamp_last_tick) + this_rq->timestamp_last_tick; /* * Note that idle threads have a prio of MAX_PRIO, for this test * to be always true for them. */ - if (TASK_PREEMPTS_CURR(p, this_rq)) - resched_task(this_rq->curr); + preempt(p, this_rq); } /* @@ -1830,7 +1693,6 @@ static int move_tasks(runqueue_t *this_r unsigned long max_nr_move, struct sched_domain *sd, enum idle_type idle, int *all_pinned) { - prio_array_t *array, *dst_array; struct list_head *head, *curr; int idx, pulled = 0, pinned = 0; task_t *tmp; @@ -1840,38 +1702,17 @@ static int move_tasks(runqueue_t *this_r pinned = 1; - /* - * We first consider expired tasks. Those will likely not be - * executed in the near future, and they are most likely to - * be cache-cold, thus switching CPUs has the least effect - * on them. - */ - if (busiest->expired->nr_active) { - array = busiest->expired; - dst_array = this_rq->expired; - } else { - array = busiest->active; - dst_array = this_rq->active; - } - -new_array: /* Start searching at priority 0: */ idx = 0; skip_bitmap: if (!idx) - idx = sched_find_first_bit(array->bitmap); + idx = sched_find_first_bit(busiest->bitmap); else - idx = find_next_bit(array->bitmap, MAX_PRIO, idx); - if (idx >= MAX_PRIO) { - if (array == busiest->expired && busiest->active->nr_active) { - array = busiest->active; - dst_array = this_rq->active; - goto new_array; - } + idx = find_next_bit(busiest->bitmap, MAX_PRIO, idx); + if (idx >= MAX_PRIO) goto out; - } - head = array->queue + idx; + head = busiest->queue + idx; curr = head->prev; skip_queue: tmp = list_entry(curr, task_t, run_list); @@ -1890,7 +1731,7 @@ skip_queue: schedstat_inc(sd, lb_hot_gained[idle]); #endif - pull_task(busiest, array, tmp, this_rq, dst_array, this_cpu); + pull_task(busiest, tmp, this_rq, this_cpu); pulled++; /* We only want to steal up to the prescribed number of tasks. */ @@ -2379,15 +2220,13 @@ static void rebalance_tick(int this_cpu, continue; interval = sd->balance_interval; - if (idle != SCHED_IDLE) - interval *= sd->busy_factor; /* scale ms to jiffies */ interval = msecs_to_jiffies(interval); if (unlikely(!interval)) interval = 1; - if (j - sd->last_balance >= interval) { + if (idle != SCHED_IDLE || j - sd->last_balance >= interval) { if (load_balance(this_cpu, this_rq, sd, idle)) { /* * We've pulled tasks over so either we're no @@ -2461,22 +2300,6 @@ unsigned long long current_sched_time(co } /* - * We place interactive tasks back into the active array, if possible. - * - * To guarantee that this does not starve expired tasks we ignore the - * interactivity of a task if the first expired task had to wait more - * than a 'reasonable' amount of time. This deadline timeout is - * load-dependent, as the frequency of array switched decreases with - * increasing number of running tasks. We also ignore the interactivity - * if a better static_prio task has expired: - */ -#define EXPIRED_STARVING(rq) \ - ((STARVATION_LIMIT && ((rq)->expired_timestamp && \ - (jiffies - (rq)->expired_timestamp >= \ - STARVATION_LIMIT * ((rq)->nr_running) + 1))) || \ - ((rq)->curr->static_prio > (rq)->best_expired_prio)) - -/* * Account user cpu time to a process. * @p: the process that the cpu time gets accounted to * @hardirq_offset: the offset to subtract from hardirq_count() @@ -2524,6 +2347,7 @@ void account_system_time(struct task_str cpustat->iowait = cputime64_add(cpustat->iowait, tmp); else cpustat->idle = cputime64_add(cpustat->idle, tmp); + /* Account for system time used */ acct_update_integrals(p); } @@ -2549,18 +2373,25 @@ void account_steal_time(struct task_stru cpustat->steal = cputime64_add(cpustat->steal, tmp); } +static void time_slice_expired(task_t *p, runqueue_t *rq) +{ + set_tsk_need_resched(p); + dequeue_task(p, rq); + p->prio = effective_prio(p); + p->time_slice = rr_interval(p); + enqueue_task(p, rq); +} + /* * This function gets called by the timer code, with HZ frequency. * We call it with interrupts disabled. - * - * It also gets called by the fork code, when changing the parent's - * timeslices. */ void scheduler_tick(void) { int cpu = smp_processor_id(); runqueue_t *rq = this_rq(); task_t *p = current; + unsigned long debit, expired_balance = rq->nr_running; unsigned long long now = sched_clock(); update_cpu_clock(p, rq, now); @@ -2575,78 +2406,48 @@ void scheduler_tick(void) } /* Task might have expired already, but not scheduled off yet */ - if (p->array != rq->active) { + if (unlikely(!task_queued(p))) { set_tsk_need_resched(p); goto out; } - spin_lock(&rq->lock); /* - * The task was running during this tick - update the - * time slice counter. Note: we do not update a thread's - * priority until it either goes to sleep or uses up its - * timeslice. This makes it possible for interactive tasks - * to use up their timeslices at their highest priority levels. + * SCHED_FIFO tasks never run out of timeslice. */ - if (rt_task(p)) { - /* - * RR tasks need a special form of timeslice management. - * FIFO tasks have no timeslices. - */ - if ((p->policy == SCHED_RR) && !--p->time_slice) { - p->time_slice = task_timeslice(p); - p->first_time_slice = 0; - set_tsk_need_resched(p); + if (unlikely(p->policy == SCHED_FIFO)) { + expired_balance = 0; + goto out; + } - /* put it at the end of the queue: */ - requeue_task(p, rq->active); - } + spin_lock(&rq->lock); + debit = ns_diff(rq->timestamp_last_tick, p->timestamp); + p->ns_debit += debit; + if (p->ns_debit < NSJIFFY) + goto out_unlock; + p->ns_debit %= NSJIFFY; + /* + * Tasks lose bonus each time they use up a full slice(). + */ + if (!--p->slice) { + dec_bonus(p); + p->slice = slice(p); + time_slice_expired(p, rq); + p->totalrun = 0; goto out_unlock; } + /* + * Tasks that run out of time_slice but still have slice left get + * requeued with a lower priority && RR_INTERVAL time_slice. + */ if (!--p->time_slice) { - dequeue_task(p, rq->active); - set_tsk_need_resched(p); - p->prio = effective_prio(p); - p->time_slice = task_timeslice(p); - p->first_time_slice = 0; - - if (!rq->expired_timestamp) - rq->expired_timestamp = jiffies; - if (!TASK_INTERACTIVE(p) || EXPIRED_STARVING(rq)) { - enqueue_task(p, rq->expired); - if (p->static_prio < rq->best_expired_prio) - rq->best_expired_prio = p->static_prio; - } else - enqueue_task(p, rq->active); - } else { - /* - * Prevent a too long timeslice allowing a task to monopolize - * the CPU. We do this by splitting up the timeslice into - * smaller pieces. - * - * Note: this does not mean the task's timeslices expire or - * get lost in any way, they just might be preempted by - * another task of equal priority. (one with higher - * priority would have preempted this task already.) We - * requeue this task to the end of the list on this priority - * level, which is in essence a round-robin of tasks with - * equal priority. - * - * This only applies to tasks in the interactive - * delta range with at least TIMESLICE_GRANULARITY to requeue. - */ - if (TASK_INTERACTIVE(p) && !((task_timeslice(p) - - p->time_slice) % TIMESLICE_GRANULARITY(p)) && - (p->time_slice >= TIMESLICE_GRANULARITY(p)) && - (p->array == rq->active)) { - - requeue_task(p, rq->active); - set_tsk_need_resched(p); - } + time_slice_expired(p, rq); + goto out_unlock; } + expired_balance = 0; out_unlock: spin_unlock(&rq->lock); out: - rebalance_tick(cpu, rq, NOT_IDLE); + if (expired_balance > 1) + rebalance_tick(cpu, rq, NOT_IDLE); } #ifdef CONFIG_SCHED_SMT @@ -2703,19 +2504,19 @@ static void wake_sleeping_dependent(int /* * number of 'lost' timeslices this task wont be able to fully - * utilize, if another task runs on a sibling. This models the + * utilise, if another task runs on a sibling. This models the * slowdown effect of other tasks running on siblings: */ -static inline unsigned long smt_slice(task_t *p, struct sched_domain *sd) +static inline unsigned long smt_slice(const task_t *p, + const struct sched_domain *sd) { - return p->time_slice * (100 - sd->per_cpu_gain) / 100; + return p->slice * (100 - sd->per_cpu_gain) / 100; } static int dependent_sleeper(int this_cpu, runqueue_t *this_rq) { struct sched_domain *tmp, *sd = NULL; cpumask_t sibling_map; - prio_array_t *array; int ret = 0, i; task_t *p; @@ -2742,12 +2543,8 @@ static int dependent_sleeper(int this_cp */ if (!this_rq->nr_running) goto out_unlock; - array = this_rq->active; - if (!array->nr_active) - array = this_rq->expired; - BUG_ON(!array->nr_active); - p = list_entry(array->queue[sched_find_first_bit(array->bitmap)].next, + p = list_entry(this_rq->queue[sched_find_first_bit(this_rq->bitmap)].next, task_t, run_list); for_each_cpu_mask(i, sibling_map) { @@ -2777,7 +2574,7 @@ static int dependent_sleeper(int this_cp } else if (smt_curr->static_prio < p->static_prio && !TASK_PREEMPTS_CURR(p, smt_rq) && - smt_slice(smt_curr, sd) > task_timeslice(p)) + smt_slice(smt_curr, sd) > slice(p)) ret = 1; check_smt_task: @@ -2800,7 +2597,7 @@ check_smt_task: resched_task(smt_curr); } else { if (TASK_PREEMPTS_CURR(p, smt_rq) && - smt_slice(p, sd) > task_timeslice(smt_curr)) + smt_slice(p, sd) > slice(smt_curr)) resched_task(smt_curr); else wakeup_busy_runqueue(smt_rq); @@ -2862,11 +2659,10 @@ asmlinkage void __sched schedule(void) long *switch_count; task_t *prev, *next; runqueue_t *rq; - prio_array_t *array; struct list_head *queue; unsigned long long now; - unsigned long run_time; - int cpu, idx, new_prio; + unsigned long debit; + int cpu, idx; /* * Test if we are atomic. Since do_exit() needs to call into @@ -2901,20 +2697,11 @@ need_resched_nonpreemptible: schedstat_inc(rq, sched_cnt); now = sched_clock(); - if (likely((long long)(now - prev->timestamp) < NS_MAX_SLEEP_AVG)) { - run_time = now - prev->timestamp; - if (unlikely((long long)(now - prev->timestamp) < 0)) - run_time = 0; - } else - run_time = NS_MAX_SLEEP_AVG; - - /* - * Tasks charged proportionately less run_time at high sleep_avg to - * delay them losing their interactive status - */ - run_time /= (CURRENT_BONUS(prev) ? : 1); spin_lock_irq(&rq->lock); + prev->runtime = ns_diff(now, prev->timestamp); + debit = ns_diff(now, rq->timestamp_last_tick) % NSJIFFY; + prev->ns_debit += debit; if (unlikely(prev->flags & PF_DEAD)) prev->state = EXIT_DEAD; @@ -2926,8 +2713,10 @@ need_resched_nonpreemptible: unlikely(signal_pending(prev)))) prev->state = TASK_RUNNING; else { - if (prev->state == TASK_UNINTERRUPTIBLE) + if (prev->state == TASK_UNINTERRUPTIBLE) { + prev->flags |= PF_NONSLEEP; rq->nr_uninterruptible++; + } deactivate_task(prev, rq); } } @@ -2938,7 +2727,6 @@ go_idle: idle_balance(cpu, rq); if (!rq->nr_running) { next = rq->idle; - rq->expired_timestamp = 0; wake_sleeping_dependent(cpu, rq); /* * wake_sleeping_dependent() might have released @@ -2962,45 +2750,15 @@ go_idle: goto go_idle; } - array = rq->active; - if (unlikely(!array->nr_active)) { - /* - * Switch the active and expired arrays. - */ - schedstat_inc(rq, sched_switch); - rq->active = rq->expired; - rq->expired = array; - array = rq->active; - rq->expired_timestamp = 0; - rq->best_expired_prio = MAX_PRIO; - } - - idx = sched_find_first_bit(array->bitmap); - queue = array->queue + idx; + idx = sched_find_first_bit(rq->bitmap); + queue = rq->queue + idx; next = list_entry(queue->next, task_t, run_list); - if (!rt_task(next) && next->activated > 0) { - unsigned long long delta = now - next->timestamp; - if (unlikely((long long)(now - next->timestamp) < 0)) - delta = 0; - - if (next->activated == 1) - delta = delta * (ON_RUNQUEUE_WEIGHT * 128 / 100) / 128; - - array = next->array; - new_prio = recalc_task_prio(next, next->timestamp + delta); - - if (unlikely(next->prio != new_prio)) { - dequeue_task(next, array); - next->prio = new_prio; - enqueue_task(next, array); - } else - requeue_task(next, array); - } - next->activated = 0; switch_tasks: if (next == rq->idle) schedstat_inc(rq, sched_goidle); + prev->timestamp = now; + prefetch(next); prefetch_stack(next); clear_tsk_need_resched(prev); @@ -3008,11 +2766,6 @@ switch_tasks: update_cpu_clock(prev, rq, now); - prev->sleep_avg -= run_time; - if ((long)prev->sleep_avg <= 0) - prev->sleep_avg = 0; - prev->timestamp = prev->last_ran = now; - sched_info_switch(prev, next); if (likely(prev != next)) { next->timestamp = now; @@ -3444,9 +3197,8 @@ EXPORT_SYMBOL(sleep_on_timeout); void set_user_nice(task_t *p, long nice) { unsigned long flags; - prio_array_t *array; runqueue_t *rq; - int old_prio, new_prio, delta; + int queued, old_prio, new_prio, delta; if (TASK_NICE(p) == nice || nice < -20 || nice > 19) return; @@ -3465,18 +3217,19 @@ void set_user_nice(task_t *p, long nice) p->static_prio = NICE_TO_PRIO(nice); goto out_unlock; } - array = p->array; - if (array) - dequeue_task(p, array); + if ((queued = task_queued(p))) + dequeue_task(p, rq); old_prio = p->prio; new_prio = NICE_TO_PRIO(nice); delta = new_prio - old_prio; p->static_prio = NICE_TO_PRIO(nice); p->prio += delta; + if (p->bonus > bonus(p)) + p->bonus= bonus(p); - if (array) { - enqueue_task(p, array); + if (queued) { + enqueue_task(p, rq); /* * If the task increased its priority or is running and * lowered its priority, then reschedule its CPU: @@ -3599,19 +3352,13 @@ static inline task_t *find_process_by_pi /* Actually do priority change: must hold rq lock. */ static void __setscheduler(struct task_struct *p, int policy, int prio) { - BUG_ON(p->array); + BUG_ON(task_queued(p)); p->policy = policy; p->rt_priority = prio; if (policy != SCHED_NORMAL && policy != SCHED_BATCH) { p->prio = MAX_RT_PRIO-1 - p->rt_priority; - } else { + } else p->prio = p->static_prio; - /* - * SCHED_BATCH tasks are treated as perpetual CPU hogs: - */ - if (policy == SCHED_BATCH) - p->sleep_avg = 0; - } } /** @@ -3625,8 +3372,7 @@ int sched_setscheduler(struct task_struc struct sched_param *param) { int retval; - int oldprio, oldpolicy = -1; - prio_array_t *array; + int queued, oldprio, oldpolicy = -1; unsigned long flags; runqueue_t *rq; @@ -3688,12 +3434,11 @@ recheck: task_rq_unlock(rq, &flags); goto recheck; } - array = p->array; - if (array) + if ((queued = task_queued(p))) deactivate_task(p, rq); oldprio = p->prio; __setscheduler(p, policy, param->sched_priority); - if (array) { + if (queued) { __activate_task(p, rq); /* * Reschedule if we are currently running on this runqueue and @@ -3703,8 +3448,8 @@ recheck: if (task_running(rq, p)) { if (p->prio > oldprio) resched_task(rq->curr); - } else if (TASK_PREEMPTS_CURR(p, rq)) - resched_task(rq->curr); + } else + preempt(p, rq); } task_rq_unlock(rq, &flags); return 0; @@ -3961,43 +3706,27 @@ asmlinkage long sys_sched_getaffinity(pi /** * sys_sched_yield - yield the current processor to other threads. - * - * this function yields the current CPU by moving the calling thread - * to the expired array. If there are no other threads running on this - * CPU then this function will return. + * This function yields the current CPU by dropping the priority of current + * to the lowest priority. */ asmlinkage long sys_sched_yield(void) { + int newprio; runqueue_t *rq = this_rq_lock(); - prio_array_t *array = current->array; - prio_array_t *target = rq->expired; + newprio = current->prio; schedstat_inc(rq, yld_cnt); - /* - * We implement yielding by moving the task into the expired - * queue. - * - * (special rule: RT tasks will just roundrobin in the active - * array.) - */ - if (rt_task(current)) - target = rq->active; - - if (array->nr_active == 1) { - schedstat_inc(rq, yld_act_empty); - if (!rq->expired->nr_active) - schedstat_inc(rq, yld_both_empty); - } else if (!rq->expired->nr_active) - schedstat_inc(rq, yld_exp_empty); - - if (array != target) { - dequeue_task(current, array); - enqueue_task(current, target); + current->slice = slice(current); + current->time_slice = rr_interval(current); + if (likely(!rt_task(current))) + newprio = MAX_PRIO - 1; + + if (newprio != current->prio) { + dequeue_task(current, rq); + current->prio = newprio; + enqueue_task(current, rq); } else - /* - * requeue_task is cheaper so perform that if possible. - */ - requeue_task(current, array); + requeue_task(current, rq); /* * Since we are going to call schedule() anyway, there's @@ -4206,7 +3935,7 @@ long sys_sched_rr_get_interval(pid_t pid goto out_unlock; jiffies_to_timespec(p->policy & SCHED_FIFO ? - 0 : task_timeslice(p), &t); + 0 : slice(p), &t); read_unlock(&tasklist_lock); retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0; out_nounlock: @@ -4329,8 +4058,6 @@ void __devinit init_idle(task_t *idle, i unsigned long flags; idle->timestamp = sched_clock(); - idle->sleep_avg = 0; - idle->array = NULL; idle->prio = MAX_PRIO; idle->state = TASK_RUNNING; idle->cpus_allowed = cpumask_of_cpu(cpu); @@ -4447,7 +4174,7 @@ static void __migrate_task(struct task_s goto out; set_task_cpu(p, dest_cpu); - if (p->array) { + if (task_queued(p)) { /* * Sync timestamp with rq_dest's before activating. * The same thing could be achieved by doing this step @@ -4458,8 +4185,7 @@ static void __migrate_task(struct task_s + rq_dest->timestamp_last_tick; deactivate_task(p, rq_src); activate_task(p, rq_dest, 0); - if (TASK_PREEMPTS_CURR(p, rq_dest)) - resched_task(rq_dest->curr); + preempt(p, rq_dest); } out: @@ -4673,7 +4399,7 @@ static void migrate_dead_tasks(unsigned for (arr = 0; arr < 2; arr++) { for (i = 0; i < MAX_PRIO; i++) { - struct list_head *list = &rq->arrays[arr].queue[i]; + struct list_head *list = &rq->queue[i]; while (!list_empty(list)) migrate_dead(dead_cpu, list_entry(list->next, task_t, @@ -6015,17 +5741,13 @@ int in_sched_functions(unsigned long add void __init sched_init(void) { runqueue_t *rq; - int i, j, k; + int i, j; for_each_cpu(i) { - prio_array_t *array; rq = cpu_rq(i); spin_lock_init(&rq->lock); rq->nr_running = 0; - rq->active = rq->arrays; - rq->expired = rq->arrays + 1; - rq->best_expired_prio = MAX_PRIO; #ifdef CONFIG_SMP rq->sd = NULL; @@ -6037,16 +5759,13 @@ void __init sched_init(void) INIT_LIST_HEAD(&rq->migration_queue); #endif atomic_set(&rq->nr_iowait, 0); - - for (j = 0; j < 2; j++) { - array = rq->arrays + j; - for (k = 0; k < MAX_PRIO; k++) { - INIT_LIST_HEAD(array->queue + k); - __clear_bit(k, array->bitmap); - } - // delimiter for bitsearch - __set_bit(MAX_PRIO, array->bitmap); - } + for (j = 0; j < MAX_PRIO; j++) + INIT_LIST_HEAD(&rq->queue[j]); + memset(rq->bitmap, 0, BITS_TO_LONGS(MAX_PRIO)*sizeof(long)); + /* + * delimiter for bitsearch + */ + __set_bit(MAX_PRIO, rq->bitmap); } /* @@ -6090,9 +5809,9 @@ EXPORT_SYMBOL(__might_sleep); void normalize_rt_tasks(void) { struct task_struct *p; - prio_array_t *array; unsigned long flags; runqueue_t *rq; + int queued; read_lock_irq(&tasklist_lock); for_each_process (p) { @@ -6101,11 +5820,10 @@ void normalize_rt_tasks(void) rq = task_rq_lock(p, &flags); - array = p->array; - if (array) + if ((queued = task_queued(p))) deactivate_task(p, task_rq(p)); __setscheduler(p, SCHED_NORMAL, 0); - if (array) { + if (queued) { __activate_task(p, task_rq(p)); resched_task(rq->curr); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/