Implement the "staircase" hybrid foreground-background single priority
array cpu scheduler policy.
Signed-off-by: Con Kolivas <[email protected]>
fs/proc/array.c | 4
include/linux/sched.h | 21 -
kernel/exit.c | 1
kernel/sched.c | 1015 ++++++++++++++++++--------------------------------
4 files changed, 378 insertions(+), 663 deletions(-)
Index: linux-ck-dev/fs/proc/array.c
===================================================================
--- linux-ck-dev.orig/fs/proc/array.c 2006-06-18 15:20:15.000000000 +1000
+++ linux-ck-dev/fs/proc/array.c 2006-06-18 15:21:50.000000000 +1000
@@ -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-ck-dev/include/linux/sched.h
===================================================================
--- linux-ck-dev.orig/include/linux/sched.h 2006-06-18 15:21:31.000000000 +1000
+++ linux-ck-dev/include/linux/sched.h 2006-06-18 15:21:50.000000000 +1000
@@ -483,6 +483,7 @@ struct signal_struct {
#define MAX_RT_PRIO MAX_USER_RT_PRIO
#define MAX_PRIO (MAX_RT_PRIO + 40)
+#define MIN_USER_PRIO (MAX_PRIO - 1)
#define rt_task(p) (unlikely((p)->prio < MAX_RT_PRIO))
#define batch_task(p) (unlikely((p)->policy == SCHED_BATCH))
@@ -518,7 +519,6 @@ 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;
@@ -687,13 +687,6 @@ struct audit_context; /* See audit.c */
struct mempolicy;
struct pipe_inode_info;
-enum sleep_type {
- SLEEP_NORMAL,
- SLEEP_NONINTERACTIVE,
- SLEEP_INTERACTIVE,
- SLEEP_INTERRUPTED,
-};
-
struct task_struct {
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */
struct thread_info *thread_info;
@@ -711,19 +704,18 @@ struct task_struct {
int load_weight; /* for niceness load balancing purposes */
int prio, static_prio;
struct list_head run_list;
- prio_array_t *array;
unsigned short ioprio;
unsigned int btrace_seq;
- unsigned long sleep_avg;
- unsigned long long timestamp, last_ran;
+ unsigned long long timestamp;
+ unsigned long runtime, totalrun, ns_debit, systime;
+ unsigned int bonus;
+ unsigned int slice, time_slice;
unsigned long long sched_time; /* sched_clock time spent running */
- enum sleep_type sleep_type;
unsigned long policy;
cpumask_t cpus_allowed;
- unsigned int time_slice, first_time_slice;
#ifdef CONFIG_SCHEDSTATS
struct sched_info sched_info;
@@ -952,6 +944,8 @@ static inline void put_task_struct(struc
#define PF_SPREAD_PAGE 0x04000000 /* Spread page cache over cpuset */
#define PF_SPREAD_SLAB 0x08000000 /* Spread some slab caches over cpuset */
#define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */
+#define PF_NONSLEEP 0x20000000 /* Waiting on in kernel activity */
+#define PF_FORKED 0x40000000 /* Task just forked another process */
/*
* Only the _current_ task can read/write to tsk->flags, but other
@@ -1073,7 +1067,6 @@ 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-ck-dev/kernel/exit.c
===================================================================
--- linux-ck-dev.orig/kernel/exit.c 2006-06-18 15:21:00.000000000 +1000
+++ linux-ck-dev/kernel/exit.c 2006-06-18 15:21:50.000000000 +1000
@@ -170,7 +170,6 @@ 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-ck-dev/kernel/sched.c
===================================================================
--- linux-ck-dev.orig/kernel/sched.c 2006-06-18 15:21:45.000000000 +1000
+++ linux-ck-dev/kernel/sched.c 2006-06-18 15:22:27.000000000 +1000
@@ -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
+ * 2006-06-18 Staircase scheduling policy by Con Kolivas with help
+ * from William Lee Irwin III, Zwane Mwaikambo & Peter Williams.
+ * Staircase v16
*/
#include <linux/mm.h>
@@ -75,131 +78,27 @@
/*
* Some helpers for converting nanosecond timing to jiffy resolution
*/
-#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) + 20, 40, MAX_BONUS) - 20 * MAX_BONUS / 40 + \
- 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 NS_TO_JIFFIES(TIME) ((TIME) / NSJIFFY)
+#define JIFFIES_TO_NS(TIME) ((TIME) * NSJIFFY)
#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 static_prio_timeslice(int static_prio)
-{
- if (static_prio < NICE_TO_PRIO(0))
- return SCALE_PRIO(DEF_TIMESLICE * 4, static_prio);
- else
- return SCALE_PRIO(DEF_TIMESLICE, static_prio);
-}
-
-static inline unsigned int task_timeslice(task_t *p)
-{
- return static_prio_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.
*
@@ -229,12 +128,11 @@ 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
@@ -499,13 +397,7 @@ 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
@@ -543,13 +435,11 @@ 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.
*
@@ -603,74 +493,81 @@ static inline void sched_info_switch(tas
#define sched_info_switch(t, next) do { } while (0)
#endif /* CONFIG_SCHEDSTATS */
-/*
- * Adding/removing a task to/from a priority array:
- */
-static void dequeue_task(struct task_struct *p, prio_array_t *array)
+#if BITS_PER_LONG < 64
+static inline void longlimit(unsigned long long *longlong)
+{
+ if (*longlong > (1 << 31))
+ *longlong = 1 << 31;
+}
+#else
+static inline void longlimit(unsigned long long *__unused)
{
- array->nr_active--;
- list_del(&p->run_list);
- if (list_empty(array->queue + p->prio))
- __clear_bit(p->prio, array->bitmap);
+}
+#endif
+
+/* Get nanosecond clock difference without overflowing unsigned long. */
+static unsigned long ns_diff(unsigned long long v1, unsigned long long v2)
+{
+ unsigned long long vdiff;
+ if (likely(v1 >= v2)) {
+ vdiff = v1 - v2;
+ longlimit(&vdiff);
+ } 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 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 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, const int prio)
{
- 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 + prio);
+ if (p->prio != prio) {
+ if (list_empty(rq->queue + p->prio))
+ __clear_bit(p->prio, rq->bitmap);
+ p->prio = prio;
+ __set_bit(prio, rq->bitmap);
+ }
+ p->ns_debit = 0;
+}
- 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);
}
+static unsigned int slice(const task_t *p);
+
/*
* To aid in avoiding the subversion of "niceness" due to uneven distribution
* of tasks with abnormal "nice" values across CPUs the contribution that
@@ -688,10 +585,9 @@ static int effective_prio(task_t *p)
#define TIME_SLICE_NICE_ZERO DEF_TIMESLICE
#define LOAD_WEIGHT(lp) \
(((lp) * SCHED_LOAD_SCALE) / TIME_SLICE_NICE_ZERO)
-#define PRIO_TO_LOAD_WEIGHT(prio) \
- LOAD_WEIGHT(static_prio_timeslice(prio))
-#define RTPRIO_TO_LOAD_WEIGHT(rp) \
- (PRIO_TO_LOAD_WEIGHT(MAX_RT_PRIO) + LOAD_WEIGHT(rp))
+#define TASK_LOAD_WEIGHT(p) LOAD_WEIGHT(slice(p))
+#define RTPRIO_TO_LOAD_WEIGHT(rp) \
+ (LOAD_WEIGHT((RR_INTERVAL + 20 + (rp))))
static void set_load_weight(task_t *p)
{
@@ -708,7 +604,7 @@ static void set_load_weight(task_t *p)
#endif
p->load_weight = RTPRIO_TO_LOAD_WEIGHT(p->rt_priority);
} else
- p->load_weight = PRIO_TO_LOAD_WEIGHT(p->static_prio);
+ p->load_weight = TASK_LOAD_WEIGHT(p);
}
static inline void inc_raw_weighted_load(runqueue_t *rq, const task_t *p)
@@ -736,13 +632,9 @@ static inline void dec_nr_running(task_t
/*
* __activate_task - move a task to the runqueue.
*/
-static void __activate_task(task_t *p, runqueue_t *rq)
+static inline void __activate_task(task_t *p, runqueue_t *rq)
{
- prio_array_t *target = rq->active;
-
- if (batch_task(p))
- target = rq->expired;
- enqueue_task(p, target);
+ enqueue_task(p, rq);
inc_nr_running(p, rq);
}
@@ -751,85 +643,181 @@ static void __activate_task(task_t *p, r
*/
static inline void __activate_idle_task(task_t *p, runqueue_t *rq)
{
- enqueue_task_head(p, rq->active);
+ enqueue_task_head(p, rq);
inc_nr_running(p, rq);
}
-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;
+ return TASK_USER_PRIO(p);
+}
- if (batch_task(p))
- sleep_time = 0;
+static unsigned int rr_interval(const task_t *p)
+{
+ int nice = TASK_NICE(p);
+
+ if (nice < 0 && !rt_task(p))
+ return RR_INTERVAL * (20 - nice) / 20;
+ return RR_INTERVAL;
+}
+
+/*
+ * slice - the duration a task runs before getting requeued at its best
+ * priority and has its bonus decremented.
+ */
+static unsigned int slice(const task_t *p)
+{
+ unsigned int slice, rr;
+
+ 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 inc_bonus(task_t *p, unsigned long totalrun, unsigned long sleep)
+{
+ unsigned int best_bonus = sleep / (totalrun + 1);
+
+ if (p->bonus >= best_bonus)
+ return;
+ best_bonus = bonus(p);
+ if (p->bonus < best_bonus)
+ p->bonus++;
+}
+
+static inline void dec_bonus(task_t *p)
+{
+ if (p->bonus)
+ p->bonus--;
+}
+
+static inline void slice_overrun(struct task_struct *p)
+{
+ unsigned long ns_slice = JIFFIES_TO_NS(p->slice);
+
+ do {
+ p->totalrun -= ns_slice;
+ dec_bonus(p);
+ } while (unlikely(p->totalrun > ns_slice));
+}
+
+/*
+ * 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 (!batch_task(p))
+ prio -= p->bonus;
+
+ rr = rr_interval(p);
+ prio += used_slice / rr;
+ if (prio > MIN_USER_PRIO)
+ prio = MIN_USER_PRIO;
+ return prio;
+}
+
+static inline void continue_slice(task_t *p)
+{
+ unsigned long total_run = NS_TO_JIFFIES(p->totalrun);
+
+ if (unlikely(total_run >= p->slice))
+ slice_overrun(p);
else {
- if (__sleep_time > NS_MAX_SLEEP_AVG)
- sleep_time = NS_MAX_SLEEP_AVG;
- else
- sleep_time = (unsigned long)__sleep_time;
+ unsigned long remainder;
+
+ p->slice -= total_run;
+ remainder = p->slice % rr_interval(p);
+ if (remainder)
+ p->time_slice = remainder;
}
+}
- if (likely(sleep_time > 0)) {
- /*
- * User tasks that sleep a long time are categorised as
- * idle. They will only have their sleep_avg increased to a
- * level that makes them just interactive priority to stay
- * active yet prevent them suddenly becoming cpu hogs and
- * starving other processes.
- */
- if (p->mm && sleep_time > INTERACTIVE_SLEEP(p)) {
- unsigned long ceiling;
+/*
+ * recalc_task_prio - this checks for tasks that have run less than a full
+ * slice and have woken up again soon after, 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;
- ceiling = JIFFIES_TO_NS(MAX_SLEEP_AVG -
- DEF_TIMESLICE);
- if (p->sleep_avg < ceiling)
- p->sleep_avg = ceiling;
- } else {
- /*
- * Tasks waking from uninterruptible sleep are
- * limited in their sleep_avg rise as they
- * are likely to be waiting on I/O
- */
- if (p->sleep_type == SLEEP_NONINTERACTIVE && 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 this task has managed to run to its lowest priority then
+ * decrease its bonus and requeue it now at best priority instead
+ * of possibly flagging around lowest priority. Save up any systime
+ * that may affect priority on the next reschedule.
+ */
+ if (p->slice > p->time_slice &&
+ p->slice - NS_TO_JIFFIES(p->totalrun) < p->time_slice) {
+ dec_bonus(p);
+ p->totalrun = 0;
+ return;
+ }
- /*
- * 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;
+ /*
+ * Add the total for this last scheduled run (p->runtime) and system
+ * time (p->systime) done on behalf of p to the running total so far
+ * used (p->totalrun).
+ */
+ p->totalrun += p->runtime + p->systime;
+ sleep_time = ns_diff(now, p->timestamp);
- if (p->sleep_avg > NS_MAX_SLEEP_AVG)
- p->sleep_avg = NS_MAX_SLEEP_AVG;
+ if (p->systime > sleep_time || p->flags & PF_FORKED)
+ sleep_time = 0;
+ else {
+ sleep_time -= p->systime;
+ /*
+ * We elevate priority by the amount of time we slept. 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) {
+ if (!(p->flags & PF_NONSLEEP))
+ inc_bonus(p, p->totalrun, sleep_time);
+ p->totalrun = 0;
+ return;
}
+ p->totalrun -= sleep_time;
}
-
- return effective_prio(p);
+ 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.)
+ * Update all the scheduling statistics stuff. (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 */
@@ -838,45 +826,25 @@ 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->sleep_type == SLEEP_NORMAL) {
- /*
- * 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->sleep_type = SLEEP_INTERRUPTED;
- else {
- /*
- * Normal first-time wakeups get a credit too for
- * on-runqueue time, but it will be weighted down:
- */
- p->sleep_type = SLEEP_INTERACTIVE;
- }
+ p->slice = slice(p);
+ p->time_slice = p->slice % rr ? : rr;
+ if (!rt_task(p)) {
+ recalc_task_prio(p, now);
+ p->prio = effective_prio(p);
+ p->systime = 0;
+ p->flags &= ~(PF_FORKED | PF_NONSLEEP);
}
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 deactivate_task(task_t *p, runqueue_t *rq)
{
dec_nr_running(p, rq);
- dequeue_task(p, p->array);
- p->array = NULL;
+ dequeue_task(p, rq);
}
/*
@@ -952,7 +920,7 @@ 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;
}
@@ -982,7 +950,7 @@ 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);
@@ -1234,6 +1202,15 @@ 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 (TASK_PREEMPTS_CURR(p, rq))
+ resched_task(rq->curr);
+}
+
/***
* try_to_wake_up - wake up a thread
* @p: the to-be-woken-up thread
@@ -1265,7 +1242,7 @@ 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);
@@ -1356,7 +1333,7 @@ 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();
@@ -1365,25 +1342,9 @@ 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->sleep_type = SLEEP_NONINTERACTIVE;
- } else
-
- /*
- * Tasks that have marked their sleep as noninteractive get
- * woken up with their sleep average not weighted in an
- * interactive way.
- */
- if (old_state & TASK_NONINTERACTIVE)
- p->sleep_type = SLEEP_NONINTERACTIVE;
-
- 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)
@@ -1392,10 +1353,9 @@ 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:
@@ -1440,7 +1400,6 @@ 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
@@ -1451,30 +1410,6 @@ 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();
}
@@ -1496,37 +1431,20 @@ void fastcall wake_up_new_task(task_t *p
this_cpu = smp_processor_id();
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.
- */
- p->sleep_avg = JIFFIES_TO_NS(CURRENT_BONUS(p) *
- CHILD_PENALTY / 100 * MAX_SLEEP_AVG / MAX_BONUS);
-
- p->prio = effective_prio(p);
+ /* Forked process gets no bonus to prevent fork bombs. */
+ p->bonus = 0;
+ current->flags |= PF_FORKED;
if (likely(cpu == this_cpu)) {
+ 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++;
- inc_nr_running(p, rq);
- }
set_need_resched();
- } else
- /* Run child last */
- __activate_task(p, rq);
+ }
/*
* We skip the following code due to cpu == this_cpu
*
@@ -1543,53 +1461,19 @@ 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->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
@@ -1885,23 +1769,21 @@ 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);
dec_nr_running(p, src_rq);
set_task_cpu(p, this_cpu);
inc_nr_running(p, this_rq);
- 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);
}
/*
@@ -1939,7 +1821,6 @@ int can_migrate_task(task_t *p, runqueue
return 1;
}
-#define rq_best_prio(rq) min((rq)->curr->prio, (rq)->best_expired_prio)
/*
* move_tasks tries to move up to max_nr_move tasks and max_load_move weighted
* load from busiest to this_rq, as part of a balancing operation within
@@ -1952,7 +1833,6 @@ static int move_tasks(runqueue_t *this_r
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, this_best_prio, busiest_best_prio;
int busiest_best_prio_seen;
@@ -1965,8 +1845,8 @@ static int move_tasks(runqueue_t *this_r
rem_load_move = max_load_move;
pinned = 1;
- this_best_prio = rq_best_prio(this_rq);
- busiest_best_prio = rq_best_prio(busiest);
+ this_best_prio = this_rq->curr->prio;
+ busiest_best_prio = busiest->curr->prio;
/*
* Enable handling of the case where there is more than one task
* with the best priority. If the current running task is one
@@ -1976,38 +1856,17 @@ static int move_tasks(runqueue_t *this_r
*/
busiest_best_prio_seen = busiest_best_prio == busiest->curr->prio;
- /*
- * 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);
@@ -2036,7 +1895,7 @@ 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++;
rem_load_move -= tmp->load_weight;
@@ -2585,15 +2444,13 @@ 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
@@ -2667,22 +2524,6 @@ 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()
@@ -2730,6 +2571,8 @@ void account_system_time(struct task_str
cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
else
cpustat->idle = cputime64_add(cpustat->idle, tmp);
+
+ p->systime += NSJIFFY;
/* Account for system time used */
acct_update_integrals(p);
}
@@ -2755,18 +2598,23 @@ 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);
+ p->time_slice = rr_interval(p);
+ requeue_task(p, rq, effective_prio(p));
+}
+
/*
* 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;
unsigned long long now = sched_clock();
update_cpu_clock(p, rq, now);
@@ -2781,73 +2629,37 @@ 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;
}
+ /* SCHED_FIFO tasks never run out of timeslice. */
+ if (unlikely(p->policy == SCHED_FIFO))
+ goto out;
+
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;
/*
- * 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.
+ * Tasks lose bonus each time they use up a full slice().
*/
- 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);
-
- /* put it at the end of the queue: */
- requeue_task(p, rq->active);
- }
+ if (!--p->slice) {
+ dec_bonus(p);
+ p->totalrun = 0;
+ p->slice = slice(p);
+ time_slice_expired(p, rq);
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;
}
out_unlock:
spin_unlock(&rq->lock);
@@ -2896,12 +2708,13 @@ 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;
}
/*
@@ -2964,7 +2777,7 @@ 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;
unlock:
@@ -3015,12 +2828,6 @@ EXPORT_SYMBOL(sub_preempt_count);
#endif
-static inline int interactive_sleep(enum sleep_type sleep_type)
-{
- return (sleep_type == SLEEP_INTERACTIVE ||
- sleep_type == SLEEP_INTERRUPTED);
-}
-
/*
* schedule() is the main scheduler function.
*/
@@ -3029,11 +2836,10 @@ 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
@@ -3066,20 +2872,11 @@ 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;
@@ -3091,8 +2888,10 @@ 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);
}
}
@@ -3102,64 +2901,30 @@ need_resched_nonpreemptible:
idle_balance(cpu, rq);
if (!rq->nr_running) {
next = rq->idle;
- rq->expired_timestamp = 0;
wake_sleeping_dependent(cpu);
goto switch_tasks;
}
}
- 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) && interactive_sleep(next->sleep_type)) {
- unsigned long long delta = now - next->timestamp;
- if (unlikely((long long)(now - next->timestamp) < 0))
- delta = 0;
-
- if (next->sleep_type == SLEEP_INTERACTIVE)
- 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);
- }
- }
- next->sleep_type = SLEEP_NORMAL;
if (dependent_sleeper(cpu, rq, next))
next = rq->idle;
+ else {
+ prefetch(next);
+ prefetch_stack(next);
+ }
switch_tasks:
if (next == rq->idle)
schedstat_inc(rq, sched_goidle);
- prefetch(next);
- prefetch_stack(next);
+ prev->timestamp = now;
clear_tsk_need_resched(prev);
rcu_qsctr_inc(task_cpu(prev));
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;
@@ -3591,9 +3356,8 @@ 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;
@@ -3612,9 +3376,8 @@ 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);
dec_raw_weighted_load(rq, p);
}
@@ -3624,9 +3387,11 @@ void set_user_nice(task_t *p, long nice)
p->static_prio = NICE_TO_PRIO(nice);
set_load_weight(p);
p->prio += delta;
+ if (p->bonus > bonus(p))
+ p->bonus= bonus(p);
- if (array) {
- enqueue_task(p, array);
+ if (queued) {
+ enqueue_task(p, rq);
inc_raw_weighted_load(rq, p);
/*
* If the task increased its priority or is running and
@@ -3750,19 +3515,13 @@ 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;
- }
set_load_weight(p);
}
@@ -3777,8 +3536,7 @@ 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;
@@ -3840,12 +3598,11 @@ 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
@@ -3855,8 +3612,8 @@ 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;
@@ -4113,43 +3870,22 @@ 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;
+ current->slice = slice(current);
+ current->time_slice = rr_interval(current);
+ if (likely(!rt_task(current)))
+ newprio = MIN_USER_PRIO;
- 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);
- } else
- /*
- * requeue_task is cheaper so perform that if possible.
- */
- requeue_task(current, array);
+ requeue_task(current, rq, newprio);
/*
* Since we are going to call schedule() anyway, there's
@@ -4358,7 +4094,7 @@ 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:
@@ -4481,8 +4217,6 @@ 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);
@@ -4599,7 +4333,7 @@ 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
@@ -4610,8 +4344,7 @@ 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:
@@ -4825,7 +4558,7 @@ 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,
@@ -6226,17 +5959,13 @@ int in_sched_functions(unsigned long add
void __init sched_init(void)
{
runqueue_t *rq;
- int i, j, k;
+ int i, j;
for_each_possible_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;
@@ -6248,16 +5977,11 @@ 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);
}
set_load_weight(&init_task);
@@ -6302,9 +6026,9 @@ 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) {
@@ -6313,11 +6037,10 @@ 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);
}
--
-ck
-
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