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-rw-r--r--arch/ia64/include/asm/cputime.h2
-rw-r--r--arch/ia64/kernel/time.c22
-rw-r--r--arch/powerpc/include/asm/cputime.h2
-rw-r--r--arch/powerpc/kernel/time.c20
-rw-r--r--arch/s390/include/asm/cputime.h1
-rw-r--r--arch/s390/kernel/vtime.c13
-rw-r--r--arch/s390/kvm/kvm-s390.c4
-rw-r--r--fs/proc/array.c4
-rw-r--r--include/linux/hardirq.h15
-rw-r--r--include/linux/kernel_stat.h17
-rw-r--r--include/linux/kvm_host.h12
-rw-r--r--include/linux/sched.h49
-rw-r--r--include/linux/vtime.h48
-rw-r--r--kernel/exit.c4
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/posix-cpu-timers.c24
-rw-r--r--kernel/sched/auto_group.c4
-rw-r--r--kernel/sched/auto_group.h5
-rw-r--r--kernel/sched/core.c11
-rw-r--r--kernel/sched/cputime.c131
-rw-r--r--kernel/sched/debug.c36
-rw-r--r--kernel/sched/fair.c914
-rw-r--r--kernel/sched/features.h5
-rw-r--r--kernel/sched/sched.h60
-rw-r--r--kernel/softirq.c6
-rw-r--r--kernel/sys.c6
26 files changed, 1082 insertions, 335 deletions
diff --git a/arch/ia64/include/asm/cputime.h b/arch/ia64/include/asm/cputime.h
index 3deac956d325..7fcf7f08ab06 100644
--- a/arch/ia64/include/asm/cputime.h
+++ b/arch/ia64/include/asm/cputime.h
@@ -103,5 +103,7 @@ static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
#define cputime64_to_clock_t(__ct) \
cputime_to_clock_t((__force cputime_t)__ct)
+extern void arch_vtime_task_switch(struct task_struct *tsk);
+
#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
#endif /* __IA64_CPUTIME_H */
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index f6388216080d..b1995efbfd21 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -83,7 +83,7 @@ static struct clocksource *itc_clocksource;
extern cputime_t cycle_to_cputime(u64 cyc);
-static void vtime_account_user(struct task_struct *tsk)
+void vtime_account_user(struct task_struct *tsk)
{
cputime_t delta_utime;
struct thread_info *ti = task_thread_info(tsk);
@@ -100,18 +100,11 @@ static void vtime_account_user(struct task_struct *tsk)
* accumulated times to the current process, and to prepare accounting on
* the next process.
*/
-void vtime_task_switch(struct task_struct *prev)
+void arch_vtime_task_switch(struct task_struct *prev)
{
struct thread_info *pi = task_thread_info(prev);
struct thread_info *ni = task_thread_info(current);
- if (idle_task(smp_processor_id()) != prev)
- vtime_account_system(prev);
- else
- vtime_account_idle(prev);
-
- vtime_account_user(prev);
-
pi->ac_stamp = ni->ac_stamp;
ni->ac_stime = ni->ac_utime = 0;
}
@@ -126,6 +119,8 @@ static cputime_t vtime_delta(struct task_struct *tsk)
cputime_t delta_stime;
__u64 now;
+ WARN_ON_ONCE(!irqs_disabled());
+
now = ia64_get_itc();
delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
@@ -147,15 +142,6 @@ void vtime_account_idle(struct task_struct *tsk)
account_idle_time(vtime_delta(tsk));
}
-/*
- * Called from the timer interrupt handler to charge accumulated user time
- * to the current process. Must be called with interrupts disabled.
- */
-void account_process_tick(struct task_struct *p, int user_tick)
-{
- vtime_account_user(p);
-}
-
#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
static irqreturn_t
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 487d46ff68a1..483733bd06d4 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -228,6 +228,8 @@ static inline cputime_t clock_t_to_cputime(const unsigned long clk)
#define cputime64_to_clock_t(ct) cputime_to_clock_t((cputime_t)(ct))
+static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+
#endif /* __KERNEL__ */
#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
#endif /* __POWERPC_CPUTIME_H */
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index ce4cb772dc78..b3b14352b05e 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -297,6 +297,8 @@ static u64 vtime_delta(struct task_struct *tsk,
u64 now, nowscaled, deltascaled;
u64 udelta, delta, user_scaled;
+ WARN_ON_ONCE(!irqs_disabled());
+
now = mftb();
nowscaled = read_spurr(now);
get_paca()->system_time += now - get_paca()->starttime;
@@ -355,15 +357,15 @@ void vtime_account_idle(struct task_struct *tsk)
}
/*
- * Transfer the user and system times accumulated in the paca
- * by the exception entry and exit code to the generic process
- * user and system time records.
+ * Transfer the user time accumulated in the paca
+ * by the exception entry and exit code to the generic
+ * process user time records.
* Must be called with interrupts disabled.
- * Assumes that vtime_account() has been called recently
- * (i.e. since the last entry from usermode) so that
+ * Assumes that vtime_account_system/idle() has been called
+ * recently (i.e. since the last entry from usermode) so that
* get_paca()->user_time_scaled is up to date.
*/
-void account_process_tick(struct task_struct *tsk, int user_tick)
+void vtime_account_user(struct task_struct *tsk)
{
cputime_t utime, utimescaled;
@@ -375,12 +377,6 @@ void account_process_tick(struct task_struct *tsk, int user_tick)
account_user_time(tsk, utime, utimescaled);
}
-void vtime_task_switch(struct task_struct *prev)
-{
- vtime_account(prev);
- account_process_tick(prev, 0);
-}
-
#else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
#define calc_cputime_factors()
#endif
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 023d5ae24482..d2ff41370c0c 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -14,6 +14,7 @@
#define __ARCH_HAS_VTIME_ACCOUNT
+#define __ARCH_HAS_VTIME_TASK_SWITCH
/* We want to use full resolution of the CPU timer: 2**-12 micro-seconds. */
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 790334427895..e84b8b68444a 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -112,7 +112,12 @@ void vtime_task_switch(struct task_struct *prev)
S390_lowcore.system_timer = ti->system_timer;
}
-void account_process_tick(struct task_struct *tsk, int user_tick)
+/*
+ * In s390, accounting pending user time also implies
+ * accounting system time in order to correctly compute
+ * the stolen time accounting.
+ */
+void vtime_account_user(struct task_struct *tsk)
{
if (do_account_vtime(tsk, HARDIRQ_OFFSET))
virt_timer_expire();
@@ -127,6 +132,8 @@ void vtime_account(struct task_struct *tsk)
struct thread_info *ti = task_thread_info(tsk);
u64 timer, system;
+ WARN_ON_ONCE(!irqs_disabled());
+
timer = S390_lowcore.last_update_timer;
S390_lowcore.last_update_timer = get_vtimer();
S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
@@ -140,6 +147,10 @@ void vtime_account(struct task_struct *tsk)
}
EXPORT_SYMBOL_GPL(vtime_account);
+void vtime_account_system(struct task_struct *tsk)
+__attribute__((alias("vtime_account")));
+EXPORT_SYMBOL_GPL(vtime_account_system);
+
void __kprobes vtime_stop_cpu(void)
{
struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index ecced9d18986..d91a95568002 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -608,9 +608,7 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
kvm_s390_deliver_pending_interrupts(vcpu);
vcpu->arch.sie_block->icptcode = 0;
- local_irq_disable();
kvm_guest_enter();
- local_irq_enable();
VCPU_EVENT(vcpu, 6, "entering sie flags %x",
atomic_read(&vcpu->arch.sie_block->cpuflags));
trace_kvm_s390_sie_enter(vcpu,
@@ -629,9 +627,7 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",
vcpu->arch.sie_block->icptcode);
trace_kvm_s390_sie_exit(vcpu, vcpu->arch.sie_block->icptcode);
- local_irq_disable();
kvm_guest_exit();
- local_irq_enable();
memcpy(&vcpu->run->s.regs.gprs[14], &vcpu->arch.sie_block->gg14, 16);
return rc;
diff --git a/fs/proc/array.c b/fs/proc/array.c
index c1c207c36cae..d3696708fc1a 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -438,7 +438,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
min_flt += sig->min_flt;
maj_flt += sig->maj_flt;
- thread_group_times(task, &utime, &stime);
+ thread_group_cputime_adjusted(task, &utime, &stime);
gtime += sig->gtime;
}
@@ -454,7 +454,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
if (!whole) {
min_flt = task->min_flt;
maj_flt = task->maj_flt;
- task_times(task, &utime, &stime);
+ task_cputime_adjusted(task, &utime, &stime);
gtime = task->gtime;
}
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index cab3da3d0949..624ef3f45c8e 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -4,6 +4,7 @@
#include <linux/preempt.h>
#include <linux/lockdep.h>
#include <linux/ftrace_irq.h>
+#include <linux/vtime.h>
#include <asm/hardirq.h>
/*
@@ -129,16 +130,6 @@ extern void synchronize_irq(unsigned int irq);
# define synchronize_irq(irq) barrier()
#endif
-struct task_struct;
-
-#if !defined(CONFIG_VIRT_CPU_ACCOUNTING) && !defined(CONFIG_IRQ_TIME_ACCOUNTING)
-static inline void vtime_account(struct task_struct *tsk)
-{
-}
-#else
-extern void vtime_account(struct task_struct *tsk);
-#endif
-
#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
static inline void rcu_nmi_enter(void)
@@ -162,7 +153,7 @@ extern void rcu_nmi_exit(void);
*/
#define __irq_enter() \
do { \
- vtime_account(current); \
+ vtime_account_irq_enter(current); \
add_preempt_count(HARDIRQ_OFFSET); \
trace_hardirq_enter(); \
} while (0)
@@ -178,7 +169,7 @@ extern void irq_enter(void);
#define __irq_exit() \
do { \
trace_hardirq_exit(); \
- vtime_account(current); \
+ vtime_account_irq_exit(current); \
sub_preempt_count(HARDIRQ_OFFSET); \
} while (0)
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 36d12f0884c3..66b70780e910 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -7,6 +7,7 @@
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
+#include <linux/vtime.h>
#include <asm/irq.h>
#include <asm/cputime.h>
@@ -126,16 +127,16 @@ extern void account_system_time(struct task_struct *, int, cputime_t, cputime_t)
extern void account_steal_time(cputime_t);
extern void account_idle_time(cputime_t);
-extern void account_process_tick(struct task_struct *, int user);
-extern void account_steal_ticks(unsigned long ticks);
-extern void account_idle_ticks(unsigned long ticks);
-
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
-extern void vtime_task_switch(struct task_struct *prev);
-extern void vtime_account_system(struct task_struct *tsk);
-extern void vtime_account_idle(struct task_struct *tsk);
+static inline void account_process_tick(struct task_struct *tsk, int user)
+{
+ vtime_account_user(tsk);
+}
#else
-static inline void vtime_task_switch(struct task_struct *prev) { }
+extern void account_process_tick(struct task_struct *, int user);
#endif
+extern void account_steal_ticks(unsigned long ticks);
+extern void account_idle_ticks(unsigned long ticks);
+
#endif /* _LINUX_KERNEL_STAT_H */
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ecc554374e44..d5cddd8dcc5c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -726,7 +726,11 @@ static inline int kvm_deassign_device(struct kvm *kvm,
static inline void kvm_guest_enter(void)
{
BUG_ON(preemptible());
- vtime_account(current);
+ /*
+ * This is running in ioctl context so we can avoid
+ * the call to vtime_account() with its unnecessary idle check.
+ */
+ vtime_account_system_irqsafe(current);
current->flags |= PF_VCPU;
/* KVM does not hold any references to rcu protected data when it
* switches CPU into a guest mode. In fact switching to a guest mode
@@ -740,7 +744,11 @@ static inline void kvm_guest_enter(void)
static inline void kvm_guest_exit(void)
{
- vtime_account(current);
+ /*
+ * This is running in ioctl context so we can avoid
+ * the call to vtime_account() with its unnecessary idle check.
+ */
+ vtime_account_system_irqsafe(current);
current->flags &= ~PF_VCPU;
}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 29116b853ece..b96ff1e43ada 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -436,13 +436,28 @@ struct cpu_itimer {
};
/**
+ * struct cputime - snaphsot of system and user cputime
+ * @utime: time spent in user mode
+ * @stime: time spent in system mode
+ *
+ * Gathers a generic snapshot of user and system time.
+ */
+struct cputime {
+ cputime_t utime;
+ cputime_t stime;
+};
+
+/**
* struct task_cputime - collected CPU time counts
* @utime: time spent in user mode, in &cputime_t units
* @stime: time spent in kernel mode, in &cputime_t units
* @sum_exec_runtime: total time spent on the CPU, in nanoseconds
*
- * This structure groups together three kinds of CPU time that are
- * tracked for threads and thread groups. Most things considering
+ * This is an extension of struct cputime that includes the total runtime
+ * spent by the task from the scheduler point of view.
+ *
+ * As a result, this structure groups together three kinds of CPU time
+ * that are tracked for threads and thread groups. Most things considering
* CPU time want to group these counts together and treat all three
* of them in parallel.
*/
@@ -583,7 +598,7 @@ struct signal_struct {
cputime_t gtime;
cputime_t cgtime;
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
- cputime_t prev_utime, prev_stime;
+ struct cputime prev_cputime;
#endif
unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
@@ -1064,6 +1079,7 @@ struct sched_class {
#ifdef CONFIG_SMP
int (*select_task_rq)(struct task_struct *p, int sd_flag, int flags);
+ void (*migrate_task_rq)(struct task_struct *p, int next_cpu);
void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);
void (*post_schedule) (struct rq *this_rq);
@@ -1098,6 +1114,18 @@ struct load_weight {
unsigned long weight, inv_weight;
};
+struct sched_avg {
+ /*
+ * These sums represent an infinite geometric series and so are bound
+ * above by 1024/(1-y). Thus we only need a u32 to store them for for all
+ * choices of y < 1-2^(-32)*1024.
+ */
+ u32 runnable_avg_sum, runnable_avg_period;
+ u64 last_runnable_update;
+ s64 decay_count;
+ unsigned long load_avg_contrib;
+};
+
#ifdef CONFIG_SCHEDSTATS
struct sched_statistics {
u64 wait_start;
@@ -1158,6 +1186,15 @@ struct sched_entity {
/* rq "owned" by this entity/group: */
struct cfs_rq *my_q;
#endif
+/*
+ * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
+ * removed when useful for applications beyond shares distribution (e.g.
+ * load-balance).
+ */
+#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
+ /* Per-entity load-tracking */
+ struct sched_avg avg;
+#endif
};
struct sched_rt_entity {
@@ -1321,7 +1358,7 @@ struct task_struct {
cputime_t utime, stime, utimescaled, stimescaled;
cputime_t gtime;
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
- cputime_t prev_utime, prev_stime;
+ struct cputime prev_cputime;
#endif
unsigned long nvcsw, nivcsw; /* context switch counts */
struct timespec start_time; /* monotonic time */
@@ -1732,8 +1769,8 @@ static inline void put_task_struct(struct task_struct *t)
__put_task_struct(t);
}
-extern void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st);
-extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st);
+extern void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st);
+extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st);
/*
* Per process flags
diff --git a/include/linux/vtime.h b/include/linux/vtime.h
new file mode 100644
index 000000000000..ae30ab58431a
--- /dev/null
+++ b/include/linux/vtime.h
@@ -0,0 +1,48 @@
+#ifndef _LINUX_KERNEL_VTIME_H
+#define _LINUX_KERNEL_VTIME_H
+
+struct task_struct;
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING
+extern void vtime_task_switch(struct task_struct *prev);
+extern void vtime_account_system(struct task_struct *tsk);
+extern void vtime_account_system_irqsafe(struct task_struct *tsk);
+extern void vtime_account_idle(struct task_struct *tsk);
+extern void vtime_account_user(struct task_struct *tsk);
+extern void vtime_account(struct task_struct *tsk);
+#else
+static inline void vtime_task_switch(struct task_struct *prev) { }
+static inline void vtime_account_system(struct task_struct *tsk) { }
+static inline void vtime_account_system_irqsafe(struct task_struct *tsk) { }
+static inline void vtime_account(struct task_struct *tsk) { }
+#endif
+
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+extern void irqtime_account_irq(struct task_struct *tsk);
+#else
+static inline void irqtime_account_irq(struct task_struct *tsk) { }
+#endif
+
+static inline void vtime_account_irq_enter(struct task_struct *tsk)
+{
+ /*
+ * Hardirq can interrupt idle task anytime. So we need vtime_account()
+ * that performs the idle check in CONFIG_VIRT_CPU_ACCOUNTING.
+ * Softirq can also interrupt idle task directly if it calls
+ * local_bh_enable(). Such case probably don't exist but we never know.
+ * Ksoftirqd is not concerned because idle time is flushed on context
+ * switch. Softirqs in the end of hardirqs are also not a problem because
+ * the idle time is flushed on hardirq time already.
+ */
+ vtime_account(tsk);
+ irqtime_account_irq(tsk);
+}
+
+static inline void vtime_account_irq_exit(struct task_struct *tsk)
+{
+ /* On hard|softirq exit we always account to hard|softirq cputime */
+ vtime_account_system(tsk);
+ irqtime_account_irq(tsk);
+}
+
+#endif /* _LINUX_KERNEL_VTIME_H */
diff --git a/kernel/exit.c b/kernel/exit.c
index 346616c0092c..618f7ee56003 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1186,11 +1186,11 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
* as other threads in the parent group can be right
* here reaping other children at the same time.
*
- * We use thread_group_times() to get times for the thread
+ * We use thread_group_cputime_adjusted() to get times for the thread
* group, which consolidates times for all threads in the
* group including the group leader.
*/
- thread_group_times(p, &tgutime, &tgstime);
+ thread_group_cputime_adjusted(p, &tgutime, &tgstime);
spin_lock_irq(&p->real_parent->sighand->siglock);
psig = p->real_parent->signal;
sig = p->signal;
diff --git a/kernel/fork.c b/kernel/fork.c
index c497e57aa654..850dde1e0c84 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1224,7 +1224,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->utime = p->stime = p->gtime = 0;
p->utimescaled = p->stimescaled = 0;
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
- p->prev_utime = p->prev_stime = 0;
+ p->prev_cputime.utime = p->prev_cputime.stime = 0;
#endif
#if defined(SPLIT_RSS_COUNTING)
memset(&p->rss_stat, 0, sizeof(p->rss_stat));
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 125cb67daa21..d73840271dce 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -217,30 +217,6 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
return 0;
}
-void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
-{
- struct signal_struct *sig = tsk->signal;
- struct task_struct *t;
-
- times->utime = sig->utime;
- times->stime = sig->stime;
- times->sum_exec_runtime = sig->sum_sched_runtime;
-
- rcu_read_lock();
- /* make sure we can trust tsk->thread_group list */
- if (!likely(pid_alive(tsk)))
- goto out;
-
- t = tsk;
- do {
- times->utime += t->utime;
- times->stime += t->stime;
- times->sum_exec_runtime += task_sched_runtime(t);
- } while_each_thread(tsk, t);
-out:
- rcu_read_unlock();
-}
-
static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
{
if (b->utime > a->utime)
diff --git a/kernel/sched/auto_group.c b/kernel/sched/auto_group.c
index 15f60d01198b..0984a21076a3 100644
--- a/kernel/sched/auto_group.c
+++ b/kernel/sched/auto_group.c
@@ -143,11 +143,15 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag)
p->signal->autogroup = autogroup_kref_get(ag);
+ if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled))
+ goto out;
+
t = p;
do {
sched_move_task(t);
} while_each_thread(p, t);
+out:
unlock_task_sighand(p, &flags);
autogroup_kref_put(prev);
}
diff --git a/kernel/sched/auto_group.h b/kernel/sched/auto_group.h
index 443232ebbb53..8bd047142816 100644
--- a/kernel/sched/auto_group.h
+++ b/kernel/sched/auto_group.h
@@ -4,6 +4,11 @@
#include <linux/rwsem.h>
struct autogroup {
+ /*
+ * reference doesn't mean how many thread attach to this
+ * autogroup now. It just stands for the number of task
+ * could use this autogroup.
+ */
struct kref kref;
struct task_group *tg;
struct rw_semaphore lock;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 80f80dfca70e..f5066a61f971 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -953,6 +953,8 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
trace_sched_migrate_task(p, new_cpu);
if (task_cpu(p) != new_cpu) {
+ if (p->sched_class->migrate_task_rq)
+ p->sched_class->migrate_task_rq(p, new_cpu);
p->se.nr_migrations++;
perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
}
@@ -1525,6 +1527,15 @@ static void __sched_fork(struct task_struct *p)
p->se.vruntime = 0;
INIT_LIST_HEAD(&p->se.group_node);
+/*
+ * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
+ * removed when useful for applications beyond shares distribution (e.g.
+ * load-balance).
+ */
+#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
+ p->se.avg.runnable_avg_period = 0;
+ p->se.avg.runnable_avg_sum = 0;
+#endif
#ifdef CONFIG_SCHEDSTATS
memset(&p->se.statistics, 0, sizeof(p->se.statistics));
#endif
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 81b763ba58a6..293b202fcf79 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -43,7 +43,7 @@ DEFINE_PER_CPU(seqcount_t, irq_time_seq);
* Called before incrementing preempt_count on {soft,}irq_enter
* and before decrementing preempt_count on {soft,}irq_exit.
*/
-void vtime_account(struct task_struct *curr)
+void irqtime_account_irq(struct task_struct *curr)
{
unsigned long flags;
s64 delta;
@@ -73,7 +73,7 @@ void vtime_account(struct task_struct *curr)
irq_time_write_end();
local_irq_restore(flags);
}
-EXPORT_SYMBOL_GPL(vtime_account);
+EXPORT_SYMBOL_GPL(irqtime_account_irq);
static int irqtime_account_hi_update(void)
{
@@ -288,6 +288,34 @@ static __always_inline bool steal_account_process_tick(void)
return false;
}
+/*
+ * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
+ * tasks (sum on group iteration) belonging to @tsk's group.
+ */
+void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
+{
+ struct signal_struct *sig = tsk->signal;
+ struct task_struct *t;
+
+ times->utime = sig->utime;
+ times->stime = sig->stime;
+ times->sum_exec_runtime = sig->sum_sched_runtime;
+
+ rcu_read_lock();
+ /* make sure we can trust tsk->thread_group list */
+ if (!likely(pid_alive(tsk)))
+ goto out;
+
+ t = tsk;
+ do {
+ times->utime += t->utime;
+ times->stime += t->stime;
+ times->sum_exec_runtime += task_sched_runtime(t);
+ } while_each_thread(tsk, t);
+out:
+ rcu_read_unlock();
+}
+
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
@@ -417,13 +445,13 @@ void account_idle_ticks(unsigned long ticks)
* Use precise platform statistics if available:
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
-void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
*ut = p->utime;
*st = p->stime;
}
-void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
struct task_cputime cputime;
@@ -433,6 +461,29 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
*st = cputime.stime;
}
+void vtime_account_system_irqsafe(struct task_struct *tsk)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ vtime_account_system(tsk);
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(vtime_account_system_irqsafe);
+
+#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
+void vtime_task_switch(struct task_struct *prev)
+{
+ if (is_idle_task(prev))
+ vtime_account_idle(prev);
+ else
+ vtime_account_system(prev);
+
+ vtime_account_user(prev);
+ arch_vtime_task_switch(prev);
+}
+#endif
+
/*
* Archs that account the whole time spent in the idle task
* (outside irq) as idle time can rely on this and just implement
@@ -444,16 +495,10 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
#ifndef __ARCH_HAS_VTIME_ACCOUNT
void vtime_account(struct task_struct *tsk)
{
- unsigned long flags;
-
- local_irq_save(flags);
-
if (in_interrupt() || !is_idle_task(tsk))
vtime_account_system(tsk);
else
vtime_account_idle(tsk);
-
- local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(vtime_account);
#endif /* __ARCH_HAS_VTIME_ACCOUNT */
@@ -478,14 +523,30 @@ static cputime_t scale_utime(cputime_t utime, cputime_t rtime, cputime_t total)
return (__force cputime_t) temp;
}
-void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+/*
+ * Adjust tick based cputime random precision against scheduler
+ * runtime accounting.
+ */
+static void cputime_adjust(struct task_cputime *curr,
+ struct cputime *prev,
+ cputime_t *ut, cputime_t *st)
{
- cputime_t rtime, utime = p->utime, total = utime + p->stime;
+ cputime_t rtime, utime, total;
+
+ utime = curr->utime;
+ total = utime + curr->stime;
/*
- * Use CFS's precise accounting:
+ * Tick based cputime accounting depend on random scheduling
+ * timeslices of a task to be interrupted or not by the timer.
+ * Depending on these circumstances, the number of these interrupts
+ * may be over or under-optimistic, matching the real user and system
+ * cputime with a variable precision.
+ *
+ * Fix this by scaling these tick based values against the total
+ * runtime accounted by the CFS scheduler.
*/
- rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
+ rtime = nsecs_to_cputime(curr->sum_exec_runtime);
if (total)
utime = scale_utime(utime, rtime, total);
@@ -493,38 +554,36 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
utime = rtime;
/*
- * Compare with previous values, to keep monotonicity:
+ * If the tick based count grows faster than the scheduler one,
+ * the result of the scaling may go backward.
+ * Let's enforce monotonicity.
*/
- p->prev_utime = max(p->prev_utime, utime);
- p->prev_stime = max(p->prev_stime, rtime - p->prev_utime);
+ prev->utime = max(prev->utime, utime);
+ prev->stime = max(prev->stime, rtime - prev->utime);
- *ut = p->prev_utime;
- *st = p->prev_stime;
+ *ut = prev->utime;
+ *st = prev->stime;
+}
+
+void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+{
+ struct task_cputime cputime = {
+ .utime = p->utime,
+ .stime = p->stime,
+ .sum_exec_runtime = p->se.sum_exec_runtime,
+ };
+
+ cputime_adjust(&cputime, &p->prev_cputime, ut, st);
}
/*
* Must be called with siglock held.
*/
-void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
- struct signal_struct *sig = p->signal;
struct task_cputime cputime;
- cputime_t rtime, utime, total;
thread_group_cputime(p, &cputime);
-
- total = cputime.utime + cputime.stime;
- rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
-
- if (total)
- utime = scale_utime(cputime.utime, rtime, total);
- else
- utime = rtime;
-
- sig->prev_utime = max(sig->prev_utime, utime);
- sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime);
-
- *ut = sig->prev_utime;
- *st = sig->prev_stime;
+ cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
}
#endif
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 6f79596e0ea9..2cd3c1b4e582 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -61,14 +61,20 @@ static unsigned long nsec_low(unsigned long long nsec)
static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg)
{
struct sched_entity *se = tg->se[cpu];
- if (!se)
- return;
#define P(F) \
SEQ_printf(m, " .%-30s: %lld\n", #F, (long long)F)
#define PN(F) \
SEQ_printf(m, " .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
+ if (!se) {
+ struct sched_avg *avg = &cpu_rq(cpu)->avg;
+ P(avg->runnable_avg_sum);
+ P(avg->runnable_avg_period);
+ return;
+ }
+
+
PN(se->exec_start);
PN(se->vruntime);
PN(se->sum_exec_runtime);
@@ -85,6 +91,12 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
P(se->statistics.wait_count);
#endif
P(se->load.weight);
+#ifdef CONFIG_SMP
+ P(se->avg.runnable_avg_sum);
+ P(se->avg.runnable_avg_period);
+ P(se->avg.load_avg_contrib);
+ P(se->avg.decay_count);
+#endif
#undef PN
#undef P
}
@@ -206,14 +218,18 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
SEQ_printf(m, " .%-30s: %ld\n", "load", cfs_rq->load.weight);
#ifdef CONFIG_FAIR_GROUP_SCHED
#ifdef CONFIG_SMP
- SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "load_avg",
- SPLIT_NS(cfs_rq->load_avg));
- SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "load_period",
- SPLIT_NS(cfs_rq->load_period));
- SEQ_printf(m, " .%-30s: %ld\n", "load_contrib",
- cfs_rq->load_contribution);
- SEQ_printf(m, " .%-30s: %d\n", "load_tg",
- atomic_read(&cfs_rq->tg->load_weight));
+ SEQ_printf(m, " .%-30s: %lld\n", "runnable_load_avg",
+ cfs_rq->runnable_load_avg);
+ SEQ_printf(m, " .%-30s: %lld\n", "blocked_load_avg",
+ cfs_rq->blocked_load_avg);
+ SEQ_printf(m, " .%-30s: %ld\n", "tg_load_avg",
+ atomic64_read(&cfs_rq->tg->load_avg));
+ SEQ_printf(m, " .%-30s: %lld\n", "tg_load_contrib",
+ cfs_rq->tg_load_contrib);
+ SEQ_printf(m, " .%-30s: %d\n", "tg_runnable_contrib",
+ cfs_rq->tg_runnable_contrib);
+ SEQ_printf(m, " .%-30s: %d\n", "tg->runnable_avg",
+ atomic_read(&cfs_rq->tg->runnable_avg));
#endif
print_cfs_group_stats(m, cpu, cfs_rq->tg);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6b800a14b990..59e072b2db97 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -259,6 +259,9 @@ static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
return grp->my_q;
}
+static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
+ int force_update);
+
static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
if (!cfs_rq->on_list) {
@@ -278,6 +281,8 @@ static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
}
cfs_rq->on_list = 1;
+ /* We should have no load, but we need to update last_decay. */
+ update_cfs_rq_blocked_load(cfs_rq, 0);
}
}
@@ -653,9 +658,6 @@ static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
return calc_delta_fair(sched_slice(cfs_rq, se), se);
}
-static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update);
-static void update_cfs_shares(struct cfs_rq *cfs_rq);
-
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
@@ -675,10 +677,6 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
curr->vruntime += delta_exec_weighted;
update_min_vruntime(cfs_rq);
-
-#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
- cfs_rq->load_unacc_exec_time += delta_exec;
-#endif
}
static void update_curr(struct cfs_rq *cfs_rq)
@@ -801,72 +799,7 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
}
#ifdef CONFIG_FAIR_GROUP_SCHED
-/* we need this in update_cfs_load and load-balance functions below */
-static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
# ifdef CONFIG_SMP
-static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq,
- int global_update)
-{
- struct task_group *tg = cfs_rq->tg;
- long load_avg;
-
- load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1);
- load_avg -= cfs_rq->load_contribution;
-
- if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) {
- atomic_add(load_avg, &tg->load_weight);
- cfs_rq->load_contribution += load_avg;
- }
-}
-
-static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
-{
- u64 period = sysctl_sched_shares_window;
- u64 now, delta;
- unsigned long load = cfs_rq->load.weight;
-
- if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq))
- return;
-
- now = rq_of(cfs_rq)->clock_task;
- delta = now - cfs_rq->load_stamp;
-
- /* truncate load history at 4 idle periods */
- if (cfs_rq->load_stamp > cfs_rq->load_last &&
- now - cfs_rq->load_last > 4 * period) {
- cfs_rq->load_period = 0;
- cfs_rq->load_avg = 0;
- delta = period - 1;
- }
-
- cfs_rq->load_stamp = now;
- cfs_rq->load_unacc_exec_time = 0;
- cfs_rq->load_period += delta;
- if (load) {
- cfs_rq->load_last = now;
- cfs_rq->load_avg += delta * load;
- }
-
- /* consider updating load contribution on each fold or truncate */
- if (global_update || cfs_rq->load_period > period
- || !cfs_rq->load_period)
- update_cfs_rq_load_contribution(cfs_rq, global_update);
-
- while (cfs_rq->load_period > period) {
- /*
- * Inline assembly required to prevent the compiler
- * optimising this loop into a divmod call.
- * See __iter_div_u64_rem() for another example of this.
- */
- asm("" : "+rm" (cfs_rq->load_period));
- cfs_rq->load_period /= 2;
- cfs_rq->load_avg /= 2;
- }
-
- if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg)
- list_del_leaf_cfs_rq(cfs_rq);
-}
-
static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
{
long tg_weight;
@@ -876,8 +809,8 @@ static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
* to gain a more accurate current total weight. See
* update_cfs_rq_load_contribution().
*/
- tg_weight = atomic_read(&tg->load_weight);
- tg_weight -= cfs_rq->load_contribution;
+ tg_weight = atomic64_read(&tg->load_avg);
+ tg_weight -= cfs_rq->tg_load_contrib;
tg_weight += cfs_rq->load.weight;
return tg_weight;
@@ -901,27 +834,11 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
return shares;
}
-
-static void update_entity_shares_tick(struct cfs_rq *cfs_rq)
-{
- if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) {
- update_cfs_load(cfs_rq, 0);
- update_cfs_shares(cfs_rq);
- }
-}
# else /* CONFIG_SMP */
-static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
-{
-}
-
static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
{
return tg->shares;
}
-
-static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
-{
-}
# endif /* CONFIG_SMP */
static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
unsigned long weight)
@@ -939,6 +856,8 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
account_entity_enqueue(cfs_rq, se);
}
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
+
static void update_cfs_shares(struct cfs_rq *cfs_rq)
{
struct task_group *tg;
@@ -958,18 +877,478 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq)
reweight_entity(cfs_rq_of(se), se, shares);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
-static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update)
+static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
{
}
+#endif /* CONFIG_FAIR_GROUP_SCHED */
-static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
+/* Only depends on SMP, FAIR_GROUP_SCHED may be removed when useful in lb */
+#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
+/*
+ * We choose a half-life close to 1 scheduling period.
+ * Note: The tables below are dependent on this value.
+ */
+#define LOAD_AVG_PERIOD 32
+#define LOAD_AVG_MAX 47742 /* maximum possible load avg */
+#define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */
+
+/* Precomputed fixed inverse multiplies for multiplication by y^n */
+static const u32 runnable_avg_yN_inv[] = {
+ 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
+ 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
+ 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
+ 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9,
+ 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80,
+ 0x85aac367, 0x82cd8698,
+};
+
+/*
+ * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent
+ * over-estimates when re-combining.
+ */
+static const u32 runnable_avg_yN_sum[] = {
+ 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103,
+ 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082,
+ 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371,
+};
+
+/*
+ * Approximate:
+ * val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
+ */
+static __always_inline u64 decay_load(u64 val, u64 n)
{
+ unsigned int local_n;
+
+ if (!n)
+ return val;
+ else if (unlikely(n > LOAD_AVG_PERIOD * 63))
+ return 0;
+
+ /* after bounds checking we can collapse to 32-bit */
+ local_n = n;
+
+ /*
+ * As y^PERIOD = 1/2, we can combine
+ * y^n = 1/2^(n/PERIOD) * k^(n%PERIOD)
+ * With a look-up table which covers k^n (n<PERIOD)
+ *
+ * To achieve constant time decay_load.
+ */
+ if (unlikely(local_n >= LOAD_AVG_PERIOD)) {
+ val >>= local_n / LOAD_AVG_PERIOD;
+ local_n %= LOAD_AVG_PERIOD;
+ }
+
+ val *= runnable_avg_yN_inv[local_n];
+ /* We don't use SRR here since we always want to round down. */
+ return val >> 32;
}
-static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq)
+/*
+ * For updates fully spanning n periods, the contribution to runnable
+ * average will be: \Sum 1024*y^n
+ *
+ * We can compute this reasonably efficiently by combining:
+ * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD}
+ */
+static u32 __compute_runnable_contrib(u64 n)
{
+ u32 contrib = 0;
+
+ if (likely(n <= LOAD_AVG_PERIOD))
+ return runnable_avg_yN_sum[n];
+ else if (unlikely(n >= LOAD_AVG_MAX_N))
+ return LOAD_AVG_MAX;
+
+ /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */
+ do {
+ contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */
+ contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD];
+
+ n -= LOAD_AVG_PERIOD;
+ } while (n > LOAD_AVG_PERIOD);
+
+ contrib = decay_load(contrib, n);
+ return contrib + runnable_avg_yN_sum[n];
}
-#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+/*
+ * We can represent the historical contribution to runnable average as the
+ * coefficients of a geometric series. To do this we sub-divide our runnable
+ * history into segments of approximately 1ms (1024us); label the segment that
+ * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
+ *
+ * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
+ * p0 p1 p2
+ * (now) (~1ms ago) (~2ms ago)
+ *
+ * Let u_i denote the fraction of p_i that the entity was runnable.
+ *
+ * We then designate the fractions u_i as our co-efficients, yielding the
+ * following representation of historical load:
+ * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
+ *
+ * We choose y based on the with of a reasonably scheduling period, fixing:
+ * y^32 = 0.5
+ *
+ * This means that the contribution to load ~32ms ago (u_32) will be weighted
+ * approximately half as much as the contribution to load within the last ms
+ * (u_0).
+ *
+ * When a period "rolls over" and we have new u_0`, multiplying the previous
+ * sum again by y is sufficient to update:
+ * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
+ * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
+ */
+static __always_inline int __update_entity_runnable_avg(u64 now,
+ struct sched_avg *sa,
+ int runnable)
+{
+ u64 delta, periods;
+ u32 runnable_contrib;
+ int delta_w, decayed = 0;
+
+ delta = now - sa->last_runnable_update;
+ /*
+ * This should only happen when time goes backwards, which it
+ * unfortunately does during sched clock init when we swap over to TSC.
+ */
+ if ((s64)delta < 0) {
+ sa->last_runnable_update = now;
+ return 0;
+ }
+
+ /*
+ * Use 1024ns as the unit of measurement since it's a reasonable
+ * approximation of 1us and fast to compute.
+ */
+ delta >>= 10;
+ if (!delta)
+ return 0;
+ sa->last_runnable_update = now;
+
+ /* delta_w is the amount already accumulated against our next period */
+ delta_w = sa->runnable_avg_period % 1024;
+ if (delta + delta_w >= 1024) {
+ /* period roll-over */
+ decayed = 1;
+
+ /*
+ * Now that we know we're crossing a period boundary, figure
+ * out how much from delta we need to complete the current
+ * period and accrue it.
+ */
+ delta_w = 1024 - delta_w;
+ if (runnable)
+ sa->runnable_avg_sum += delta_w;
+ sa->runnable_avg_period += delta_w;
+
+ delta -= delta_w;
+
+ /* Figure out how many additional periods this update spans */
+ periods = delta / 1024;
+ delta %= 1024;
+
+ sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
+ periods + 1);
+ sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
+ periods + 1);
+
+ /* Efficiently calculate \sum (1..n_period) 1024*y^i */
+ runnable_contrib = __compute_runnable_contrib(periods);
+ if (runnable)
+ sa->runnable_avg_sum += runnable_contrib;
+ sa->runnable_avg_period += runnable_contrib;
+ }
+
+ /* Remainder of delta accrued against u_0` */
+ if (runnable)
+ sa->runnable_avg_sum += delta;
+ sa->runnable_avg_period += delta;
+
+ return decayed;
+}
+
+/* Synchronize an entity's decay with its parenting cfs_rq.*/
+static inline u64 __synchronize_entity_decay(struct sched_entity *se)
+{
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ u64 decays = atomic64_read(&cfs_rq->decay_counter);
+
+ decays -= se->avg.decay_count;
+ if (!decays)
+ return 0;
+
+ se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
+ se->avg.decay_count = 0;
+
+ return decays;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
+ int force_update)
+{
+ struct task_group *tg = cfs_rq->tg;
+ s64 tg_contrib;
+
+ tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg;
+ tg_contrib -= cfs_rq->tg_load_contrib;
+
+ if (force_update || abs64(tg_contrib) > cfs_rq->tg_load_contrib / 8) {
+ atomic64_add(tg_contrib, &tg->load_avg);
+ cfs_rq->tg_load_contrib += tg_contrib;
+ }
+}
+
+/*
+ * Aggregate cfs_rq runnable averages into an equivalent task_group
+ * representation for computing load contributions.
+ */
+static inline void __update_tg_runnable_avg(struct sched_avg *sa,
+ struct cfs_rq *cfs_rq)
+{
+ struct task_group *tg = cfs_rq->tg;
+ long contrib;
+
+ /* The fraction of a cpu used by this cfs_rq */
+ contrib = div_u64(sa->runnable_avg_sum << NICE_0_SHIFT,
+ sa->runnable_avg_period + 1);
+ contrib -= cfs_rq->tg_runnable_contrib;
+
+ if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) {
+ atomic_add(contrib, &tg->runnable_avg);
+ cfs_rq->tg_runnable_contrib += contrib;
+ }
+}
+
+static inline void __update_group_entity_contrib(struct sched_entity *se)
+{
+ struct cfs_rq *cfs_rq = group_cfs_rq(se);
+ struct task_group *tg = cfs_rq->tg;
+ int runnable_avg;
+
+ u64 contrib;
+
+ contrib = cfs_rq->tg_load_contrib * tg->shares;
+ se->avg.load_avg_contrib = div64_u64(contrib,
+ atomic64_read(&tg->load_avg) + 1);
+
+ /*
+ * For group entities we need to compute a correction term in the case
+ * that they are consuming <1 cpu so that we would contribute the same
+ * load as a task of equal weight.
+ *
+ * Explicitly co-ordinating this measurement would be expensive, but
+ * fortunately the sum of each cpus contribution forms a usable
+ * lower-bound on the true value.
+ *
+ * Consider the aggregate of 2 contributions. Either they are disjoint
+ * (and the sum represents true value) or they are disjoint and we are
+ * understating by the aggregate of their overlap.
+ *
+ * Extending this to N cpus, for a given overlap, the maximum amount we
+ * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of
+ * cpus that overlap for this interval and w_i is the interval width.
+ *
+ * On a small machine; the first term is well-bounded which bounds the
+ * total error since w_i is a subset of the period. Whereas on a
+ * larger machine, while this first term can be larger, if w_i is the
+ * of consequential size guaranteed to see n_i*w_i quickly converge to
+ * our upper bound of 1-cpu.
+ */
+ runnable_avg = atomic_read(&tg->runnable_avg);
+ if (runnable_avg < NICE_0_LOAD) {
+ se->avg.load_avg_contrib *= runnable_avg;
+ se->avg.load_avg_contrib >>= NICE_0_SHIFT;
+ }
+}
+#else
+static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
+ int force_update) {}
+static inline void __update_tg_runnable_avg(struct sched_avg *sa,
+ struct cfs_rq *cfs_rq) {}
+static inline void __update_group_entity_contrib(struct sched_entity *se) {}
+#endif
+
+static inline void __update_task_entity_contrib(struct sched_entity *se)
+{
+ u32 contrib;
+
+ /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
+ contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
+ contrib /= (se->avg.runnable_avg_period + 1);
+ se->avg.load_avg_contrib = scale_load(contrib);
+}
+
+/* Compute the current contribution to load_avg by se, return any delta */
+static long __update_entity_load_avg_contrib(struct sched_entity *se)
+{
+ long old_contrib = se->avg.load_avg_contrib;
+
+ if (entity_is_task(se)) {
+ __update_task_entity_contrib(se);
+ } else {
+ __update_tg_runnable_avg(&se->avg, group_cfs_rq(se));
+ __update_group_entity_contrib(se);
+ }
+
+ return se->avg.load_avg_contrib - old_contrib;
+}
+
+static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
+ long load_contrib)
+{
+ if (likely(load_contrib < cfs_rq->blocked_load_avg))
+ cfs_rq->blocked_load_avg -= load_contrib;
+ else
+ cfs_rq->blocked_load_avg = 0;
+}
+
+static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
+
+/* Update a sched_entity's runnable average */
+static inline void update_entity_load_avg(struct sched_entity *se,
+ int update_cfs_rq)
+{
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ long contrib_delta;
+ u64 now;
+
+ /*
+ * For a group entity we need to use their owned cfs_rq_clock_task() in
+ * case they are the parent of a throttled hierarchy.
+ */
+ if (entity_is_task(se))
+ now = cfs_rq_clock_task(cfs_rq);
+ else
+ now = cfs_rq_clock_task(group_cfs_rq(se));
+
+ if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq))
+ return;
+
+ contrib_delta = __update_entity_load_avg_contrib(se);
+
+ if (!update_cfs_rq)
+ return;
+
+ if (se->on_rq)
+ cfs_rq->runnable_load_avg += contrib_delta;
+ else
+ subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
+}
+
+/*
+ * Decay the load contributed by all blocked children and account this so that
+ * their contribution may appropriately discounted when they wake up.
+ */
+static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
+{
+ u64 now = cfs_rq_clock_task(cfs_rq) >> 20;
+ u64 decays;
+
+ decays = now - cfs_rq->last_decay;
+ if (!decays && !force_update)
+ return;
+
+ if (atomic64_read(&cfs_rq->removed_load)) {
+ u64 removed_load = atomic64_xchg(&cfs_rq->removed_load, 0);
+ subtract_blocked_load_contrib(cfs_rq, removed_load);
+ }
+
+ if (decays) {
+ cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg,
+ decays);
+ atomic64_add(decays, &cfs_rq->decay_counter);
+ cfs_rq->last_decay = now;
+ }
+
+ __update_cfs_rq_tg_load_contrib(cfs_rq, force_update);
+ update_cfs_shares(cfs_rq);
+}
+
+static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
+{
+ __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable);
+ __update_tg_runnable_avg(&rq->avg, &rq->cfs);
+}
+
+/* Add the load generated by se into cfs_rq's child load-average */
+static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
+ struct sched_entity *se,
+ int wakeup)
+{
+ /*
+ * We track migrations using entity decay_count <= 0, on a wake-up
+ * migration we use a negative decay count to track the remote decays
+ * accumulated while sleeping.
+ */
+ if (unlikely(se->avg.decay_count <= 0)) {
+ se->avg.last_runnable_update = rq_of(cfs_rq)->clock_task;
+ if (se->avg.decay_count) {
+ /*
+ * In a wake-up migration we have to approximate the
+ * time sleeping. This is because we can't synchronize
+ * clock_task between the two cpus, and it is not
+ * guaranteed to be read-safe. Instead, we can
+ * approximate this using our carried decays, which are
+ * explicitly atomically readable.
+ */
+ se->avg.last_runnable_update -= (-se->avg.decay_count)
+ << 20;
+ update_entity_load_avg(se, 0);
+ /* Indicate that we're now synchronized and on-rq */
+ se->avg.decay_count = 0;
+ }
+ wakeup = 0;
+ } else {
+ __synchronize_entity_decay(se);
+ }
+
+ /* migrated tasks did not contribute to our blocked load */
+ if (wakeup) {
+ subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
+ update_entity_load_avg(se, 0);
+ }
+
+ cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
+ /* we force update consideration on load-balancer moves */
+ update_cfs_rq_blocked_load(cfs_rq, !wakeup);
+}
+
+/*
+ * Remove se's load from this cfs_rq child load-average, if the entity is
+ * transitioning to a blocked state we track its projected decay using
+ * blocked_load_avg.
+ */
+static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
+ struct sched_entity *se,
+ int sleep)
+{
+ update_entity_load_avg(se, 1);
+ /* we force update consideration on load-balancer moves */
+ update_cfs_rq_blocked_load(cfs_rq, !sleep);
+
+ cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
+ if (sleep) {
+ cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
+ se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
+ } /* migrations, e.g. sleep=0 leave decay_count == 0 */
+}
+#else
+static inline void update_entity_load_avg(struct sched_entity *se,
+ int update_cfs_rq) {}
+static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
+static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
+ struct sched_entity *se,
+ int wakeup) {}
+static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
+ struct sched_entity *se,
+ int sleep) {}
+static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
+ int force_update) {}
+#endif
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
@@ -1096,9 +1475,8 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
- update_cfs_load(cfs_rq, 0);
account_entity_enqueue(cfs_rq, se);
- update_cfs_shares(cfs_rq);
+ enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP);
if (flags & ENQUEUE_WAKEUP) {
place_entity(cfs_rq, se, 0);
@@ -1190,9 +1568,8 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
if (se != cfs_rq->curr)
__dequeue_entity(cfs_rq, se);
- se->on_rq = 0;
- update_cfs_load(cfs_rq, 0);
account_entity_dequeue(cfs_rq, se);
+ dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP);
/*
* Normalize the entity after updating the min_vruntime because the
@@ -1206,7 +1583,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
return_cfs_rq_runtime(cfs_rq);
update_min_vruntime(cfs_rq);
- update_cfs_shares(cfs_rq);
+ se->on_rq = 0;
}
/*
@@ -1340,6 +1717,8 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
update_stats_wait_start(cfs_rq, prev);
/* Put 'current' back into the tree. */
__enqueue_entity(cfs_rq, prev);
+ /* in !on_rq case, update occurred at dequeue */
+ update_entity_load_avg(prev, 1);
}
cfs_rq->curr = NULL;
}
@@ -1353,9 +1732,10 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
update_curr(cfs_rq);
/*
- * Update share accounting for long-running entities.
+ * Ensure that runnable average is periodically updated.
*/
- update_entity_shares_tick(cfs_rq);
+ update_entity_load_avg(curr, 1);
+ update_cfs_rq_blocked_load(cfs_rq, 1);
#ifdef CONFIG_SCHED_HRTICK
/*
@@ -1448,6 +1828,15 @@ static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
return &tg->cfs_bandwidth;
}
+/* rq->task_clock normalized against any time this cfs_rq has spent throttled */
+static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
+{
+ if (unlikely(cfs_rq->throttle_count))
+ return cfs_rq->throttled_clock_task;
+
+ return rq_of(cfs_rq)->clock_task - cfs_rq->throttled_clock_task_time;
+}
+
/* returns 0 on failure to allocate runtime */
static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
{
@@ -1592,14 +1981,9 @@ static int tg_unthrottle_up(struct task_group *tg, void *data)
cfs_rq->throttle_count--;
#ifdef CONFIG_SMP
if (!cfs_rq->throttle_count) {
- u64 delta = rq->clock_task - cfs_rq->load_stamp;
-
- /* leaving throttled state, advance shares averaging windows */
- cfs_rq->load_stamp += delta;
- cfs_rq->load_last += delta;
-
- /* update entity weight now that we are on_rq again */
- update_cfs_shares(cfs_rq);
+ /* adjust cfs_rq_clock_task() */
+ cfs_rq->throttled_clock_task_time += rq->clock_task -
+ cfs_rq->throttled_clock_task;
}
#endif
@@ -1611,9 +1995,9 @@ static int tg_throttle_down(struct task_group *tg, void *data)
struct rq *rq = data;
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
- /* group is entering throttled state, record last load */
+ /* group is entering throttled state, stop time */
if (!cfs_rq->throttle_count)
- update_cfs_load(cfs_rq, 0);
+ cfs_rq->throttled_clock_task = rq->clock_task;
cfs_rq->throttle_count++;
return 0;
@@ -1628,7 +2012,7 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
- /* account load preceding throttle */
+ /* freeze hierarchy runnable averages while throttled */
rcu_read_lock();
walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
rcu_read_unlock();
@@ -1652,7 +2036,7 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
rq->nr_running -= task_delta;
cfs_rq->throttled = 1;
- cfs_rq->throttled_timestamp = rq->clock;
+ cfs_rq->throttled_clock = rq->clock;
raw_spin_lock(&cfs_b->lock);
list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
raw_spin_unlock(&cfs_b->lock);
@@ -1670,10 +2054,9 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
cfs_rq->throttled = 0;
raw_spin_lock(&cfs_b->lock);
- cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp;
+ cfs_b->throttled_time += rq->clock - cfs_rq->throttled_clock;
list_del_rcu(&cfs_rq->throttled_list);
raw_spin_unlock(&cfs_b->lock);
- cfs_rq->throttled_timestamp = 0;
update_rq_clock(rq);
/* update hierarchical throttle state */
@@ -2073,8 +2456,13 @@ static void unthrottle_offline_cfs_rqs(struct rq *rq)
}
#else /* CONFIG_CFS_BANDWIDTH */
-static __always_inline
-void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec) {}
+static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
+{
+ return rq_of(cfs_rq)->clock_task;
+}
+
+static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec) {}
static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
@@ -2207,12 +2595,14 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;
- update_cfs_load(cfs_rq, 0);
- update_cfs_shares(cfs_rq);
+ update_entity_load_avg(se, 1);
+ update_cfs_rq_blocked_load(cfs_rq, 0);
}
- if (!se)
+ if (!se) {
+ update_rq_runnable_avg(rq, rq->nr_running);
inc_nr_running(rq);
+ }
hrtick_update(rq);
}
@@ -2266,12 +2656,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;
- update_cfs_load(cfs_rq, 0);
- update_cfs_shares(cfs_rq);
+ update_entity_load_avg(se, 1);
+ update_cfs_rq_blocked_load(cfs_rq, 0);
}
- if (!se)
+ if (!se) {
dec_nr_running(rq);
+ update_rq_runnable_avg(rq, 1);
+ }
hrtick_update(rq);
}
@@ -2781,6 +3173,37 @@ unlock:
return new_cpu;
}
+
+/*
+ * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
+ * removed when useful for applications beyond shares distribution (e.g.
+ * load-balance).
+ */
+#ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * Called immediately before a task is migrated to a new cpu; task_cpu(p) and
+ * cfs_rq_of(p) references at time of call are still valid and identify the
+ * previous cpu. However, the caller only guarantees p->pi_lock is held; no
+ * other assumptions, including the state of rq->lock, should be made.
+ */
+static void
+migrate_task_rq_fair(struct task_struct *p, int next_cpu)
+{
+ struct sched_entity *se = &p->se;
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
+ /*
+ * Load tracking: accumulate removed load so that it can be processed
+ * when we next update owning cfs_rq under rq->lock. Tasks contribute
+ * to blocked load iff they have a positive decay-count. It can never
+ * be negative here since on-rq tasks have decay-count == 0.
+ */
+ if (se->avg.decay_count) {
+ se->avg.decay_count = -__synchronize_entity_decay(se);
+ atomic64_add(se->avg.load_avg_contrib, &cfs_rq->removed_load);
+ }
+}
+#endif
#endif /* CONFIG_SMP */
static unsigned long
@@ -2907,7 +3330,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
* Batch and idle tasks do not preempt non-idle tasks (their preemption
* is driven by the tick):
*/
- if (unlikely(p->policy != SCHED_NORMAL))
+ if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
return;
find_matching_se(&se, &pse);
@@ -3033,8 +3456,122 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp
#ifdef CONFIG_SMP
/**************************************************
- * Fair scheduling class load-balancing methods:
- */
+ * Fair scheduling class load-balancing methods.
+ *
+ * BASICS
+ *
+ * The purpose of load-balancing is to achieve the same basic fairness the
+ * per-cpu scheduler provides, namely provide a proportional amount of compute
+ * time to each task. This is expressed in the following equation:
+ *
+ * W_i,n/P_i == W_j,n/P_j for all i,j (1)
+ *
+ * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight
+ * W_i,0 is defined as:
+ *
+ * W_i,0 = \Sum_j w_i,j (2)
+ *
+ * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight
+ * is derived from the nice value as per prio_to_weight[].
+ *
+ * The weight average is an exponential decay average of the instantaneous
+ * weight:
+ *
+ * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
+ *
+ * P_i is the cpu power (or compute capacity) of cpu i, typically it is the
+ * fraction of 'recent' time available for SCHED_OTHER task execution. But it
+ * can also include other factors [XXX].
+ *
+ * To achieve this balance we define a measure of imbalance which follows
+ * directly from (1):
+ *
+ * imb_i,j = max{ avg(W/P), W_i/P_i } - min{ avg(W/P), W_j/P_j } (4)
+ *
+ * We them move tasks around to minimize the imbalance. In the continuous
+ * function space it is obvious this converges, in the discrete case we get
+ * a few fun cases generally called infeasible weight scenarios.
+ *
+ * [XXX expand on:
+ * - infeasible weights;
+ * - local vs global optima in the discrete case. ]
+ *
+ *
+ * SCHED DOMAINS
+ *
+ * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
+ * for all i,j solution, we create a tree of cpus that follows the hardware
+ * topology where each level pairs two lower groups (or better). This results
+ * in O(log n) layers. Furthermore we reduce the number of cpus going up the
+ * tree to only the first of the previous level and we decrease the frequency
+ * of load-balance at each level inv. proportional to the number of cpus in
+ * the groups.
+ *
+ * This yields:
+ *
+ * log_2 n 1 n
+ * \Sum { --- * --- * 2^i } = O(n) (5)
+ * i = 0 2^i 2^i
+ * `- size of each group
+ * | | `- number of cpus doing load-balance
+ * | `- freq
+ * `- sum over all levels
+ *
+ * Coupled with a limit on how many tasks we can migrate every balance pass,
+ * this makes (5) the runtime complexity of the balancer.
+ *
+ * An important property here is that each CPU is still (indirectly) connected
+ * to every other cpu in at most O(log n) steps:
+ *
+ * The adjacency matrix of the resulting graph is given by:
+ *
+ * log_2 n
+ * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6)
+ * k = 0
+ *
+ * And you'll find that:
+ *
+ * A^(log_2 n)_i,j != 0 for all i,j (7)
+ *
+ * Showing there's indeed a path between every cpu in at most O(log n) steps.
+ * The task movement gives a factor of O(m), giving a convergence complexity
+ * of:
+ *
+ * O(nm log n), n := nr_cpus, m := nr_tasks (8)
+ *
+ *
+ * WORK CONSERVING
+ *
+ * In order to avoid CPUs going idle while there's still work to do, new idle
+ * balancing is more aggressive and has the newly idle cpu iterate up the domain
+ * tree itself instead of relying on other CPUs to bring it work.
+ *
+ * This adds some complexity to both (5) and (8) but it reduces the total idle
+ * time.
+ *
+ * [XXX more?]
+ *
+ *
+ * CGROUPS
+ *
+ * Cgroups make a horror show out of (2), instead of a simple sum we get:
+ *
+ * s_k,i
+ * W_i,0 = \Sum_j \Prod_k w_k * ----- (9)
+ * S_k
+ *
+ * Where
+ *
+ * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
+ *
+ * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i.
+ *
+ * The big problem is S_k, its a global sum needed to compute a local (W_i)
+ * property.
+ *
+ * [XXX write more on how we solve this.. _after_ merging pjt's patches that
+ * rewrite all of this once again.]
+ */
static unsigned long __read_mostly max_load_balance_interval = HZ/10;
@@ -3300,52 +3837,58 @@ next:
/*
* update tg->load_weight by folding this cpu's load_avg
*/
-static int update_shares_cpu(struct task_group *tg, int cpu)
+static void __update_blocked_averages_cpu(struct task_group *tg, int cpu)
{
- struct cfs_rq *cfs_rq;
- unsigned long flags;
- struct rq *rq;
-
- if (!tg->se[cpu])
- return 0;
-
- rq = cpu_rq(cpu);
- cfs_rq = tg->cfs_rq[cpu];
-
- raw_spin_lock_irqsave(&rq->lock, flags);
+ struct sched_entity *se = tg->se[cpu];
+ struct cfs_rq *cfs_rq = tg->cfs_rq[cpu];
- update_rq_clock(rq);
- update_cfs_load(cfs_rq, 1);
+ /* throttled entities do not contribute to load */
+ if (throttled_hierarchy(cfs_rq))
+ return;
- /*
- * We need to update shares after updating tg->load_weight in
- * order to adjust the weight of groups with long running tasks.
- */
- update_cfs_shares(cfs_rq);
+ update_cfs_rq_blocked_load(cfs_rq, 1);
- raw_spin_unlock_irqrestore(&rq->lock, flags);
-
- return 0;
+ if (se) {
+ update_entity_load_avg(se, 1);
+ /*
+ * We pivot on our runnable average having decayed to zero for
+ * list removal. This generally implies that all our children
+ * have also been removed (modulo rounding error or bandwidth
+ * control); however, such cases are rare and we can fix these
+ * at enqueue.
+ *
+ * TODO: fix up out-of-order children on enqueue.
+ */
+ if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running)
+ list_del_leaf_cfs_rq(cfs_rq);
+ } else {
+ struct rq *rq = rq_of(cfs_rq);
+ update_rq_runnable_avg(rq, rq->nr_running);
+ }
}
-static void update_shares(int cpu)
+static void update_blocked_averages(int cpu)
{
- struct cfs_rq *cfs_rq;
struct rq *rq = cpu_rq(cpu);
+ struct cfs_rq *cfs_rq;
+ unsigned long flags;
- rcu_read_lock();
+ raw_spin_lock_irqsave(&rq->lock, flags);
+ update_rq_clock(rq);
/*
* Iterates the task_group tree in a bottom up fashion, see
* list_add_leaf_cfs_rq() for details.
*/
for_each_leaf_cfs_rq(rq, cfs_rq) {
- /* throttled entities do not contribute to load */
- if (throttled_hierarchy(cfs_rq))
- continue;
-
- update_shares_cpu(cfs_rq->tg, cpu);
+ /*
+ * Note: We may want to consider periodically releasing
+ * rq->lock about these updates so that creating many task
+ * groups does not result in continually extending hold time.
+ */
+ __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu);
}
- rcu_read_unlock();
+
+ raw_spin_unlock_irqrestore(&rq->lock, flags);
}
/*
@@ -3397,7 +3940,7 @@ static unsigned long task_h_load(struct task_struct *p)
return load;
}
#else
-static inline void update_shares(int cpu)
+static inline void update_blocked_averages(int cpu)
{
}
@@ -4457,12 +5000,14 @@ void idle_balance(int this_cpu, struct rq *this_rq)
if (this_rq->avg_idle < sysctl_sched_migration_cost)
return;
+ update_rq_runnable_avg(this_rq, 1);
+
/*
* Drop the rq->lock, but keep IRQ/preempt disabled.
*/
raw_spin_unlock(&this_rq->lock);
- update_shares(this_cpu);
+ update_blocked_averages(this_cpu);
rcu_read_lock();
for_each_domain(this_cpu, sd) {
unsigned long interval;
@@ -4717,7 +5262,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
int update_next_balance = 0;
int need_serialize;
- update_shares(cpu);
+ update_blocked_averages(cpu);
rcu_read_lock();
for_each_domain(cpu, sd) {
@@ -4954,6 +5499,8 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
cfs_rq = cfs_rq_of(se);
entity_tick(cfs_rq, se, queued);
}
+
+ update_rq_runnable_avg(rq, 1);
}
/*
@@ -5046,6 +5593,20 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
place_entity(cfs_rq, se, 0);
se->vruntime -= cfs_rq->min_vruntime;
}
+
+#if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
+ /*
+ * Remove our load from contribution when we leave sched_fair
+ * and ensure we don't carry in an old decay_count if we
+ * switch back.
+ */
+ if (p->se.avg.decay_count) {
+ struct cfs_rq *cfs_rq = cfs_rq_of(&p->se);
+ __synchronize_entity_decay(&p->se);
+ subtract_blocked_load_contrib(cfs_rq,
+ p->se.avg.load_avg_contrib);
+ }
+#endif
}
/*
@@ -5092,11 +5653,16 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
#ifndef CONFIG_64BIT
cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
#endif
+#if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
+ atomic64_set(&cfs_rq->decay_counter, 1);
+ atomic64_set(&cfs_rq->removed_load, 0);
+#endif
}
#ifdef CONFIG_FAIR_GROUP_SCHED
static void task_move_group_fair(struct task_struct *p, int on_rq)
{
+ struct cfs_rq *cfs_rq;
/*
* If the task was not on the rq at the time of this cgroup movement
* it must have been asleep, sleeping tasks keep their ->vruntime
@@ -5128,8 +5694,19 @@ static void task_move_group_fair(struct task_struct *p, int on_rq)
if (!on_rq)
p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
set_task_rq(p, task_cpu(p));
- if (!on_rq)
- p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;
+ if (!on_rq) {
+ cfs_rq = cfs_rq_of(&p->se);
+ p->se.vruntime += cfs_rq->min_vruntime;
+#ifdef CONFIG_SMP
+ /*
+ * migrate_task_rq_fair() will have removed our previous
+ * contribution, but we must synchronize for ongoing future
+ * decay.
+ */
+ p->se.avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
+ cfs_rq->blocked_load_avg += p->se.avg.load_avg_contrib;
+#endif
+ }
}
void free_fair_sched_group(struct task_group *tg)
@@ -5214,10 +5791,6 @@ void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
cfs_rq->tg = tg;
cfs_rq->rq = rq;
-#ifdef CONFIG_SMP
- /* allow initial update_cfs_load() to truncate */
- cfs_rq->load_stamp = 1;
-#endif
init_cfs_rq_runtime(cfs_rq);
tg->cfs_rq[cpu] = cfs_rq;
@@ -5264,8 +5837,11 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
se = tg->se[i];
/* Propagate contribution to hierarchy */
raw_spin_lock_irqsave(&rq->lock, flags);
- for_each_sched_entity(se)
+ for_each_sched_entity(se) {
update_cfs_shares(group_cfs_rq(se));
+ /* update contribution to parent */
+ update_entity_load_avg(se, 1);
+ }
raw_spin_unlock_irqrestore(&rq->lock, flags);
}
@@ -5319,7 +5895,9 @@ const struct sched_class fair_sched_class = {
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_fair,
-
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ .migrate_task_rq = migrate_task_rq_fair,
+#endif
.rq_online = rq_online_fair,
.rq_offline = rq_offline_fair,
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index eebefcad7027..e68e69ab917d 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -32,6 +32,11 @@ SCHED_FEAT(LAST_BUDDY, true)
SCHED_FEAT(CACHE_HOT_BUDDY, true)
/*
+ * Allow wakeup-time preemption of the current task:
+ */
+SCHED_FEAT(WAKEUP_PREEMPTION, true)
+
+/*
* Use arch dependent cpu power functions
*/
SCHED_FEAT(ARCH_POWER, true)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 7a7db09cfabc..5eca173b563f 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -112,6 +112,8 @@ struct task_group {
unsigned long shares;
atomic_t load_weight;
+ atomic64_t load_avg;
+ atomic_t runnable_avg;
#endif
#ifdef CONFIG_RT_GROUP_SCHED
@@ -222,22 +224,29 @@ struct cfs_rq {
unsigned int nr_spread_over;
#endif
+#ifdef CONFIG_SMP
+/*
+ * Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
+ * removed when useful for applications beyond shares distribution (e.g.
+ * load-balance).
+ */
#ifdef CONFIG_FAIR_GROUP_SCHED
- struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
-
/*
- * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
- * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
- * (like users, containers etc.)
- *
- * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
- * list is used during load balance.
+ * CFS Load tracking
+ * Under CFS, load is tracked on a per-entity basis and aggregated up.
+ * This allows for the description of both thread and group usage (in
+ * the FAIR_GROUP_SCHED case).
*/
- int on_list;
- struct list_head leaf_cfs_rq_list;
- struct task_group *tg; /* group that "owns" this runqueue */
+ u64 runnable_load_avg, blocked_load_avg;
+ atomic64_t decay_counter, removed_load;
+ u64 last_decay;
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+/* These always depend on CONFIG_FAIR_GROUP_SCHED */
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ u32 tg_runnable_contrib;
+ u64 tg_load_contrib;
+#endif /* CONFIG_FAIR_GROUP_SCHED */
-#ifdef CONFIG_SMP
/*
* h_load = weight * f(tg)
*
@@ -245,26 +254,30 @@ struct cfs_rq {
* this group.
*/
unsigned long h_load;
+#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+ struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
/*
- * Maintaining per-cpu shares distribution for group scheduling
+ * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
+ * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
+ * (like users, containers etc.)
*
- * load_stamp is the last time we updated the load average
- * load_last is the last time we updated the load average and saw load
- * load_unacc_exec_time is currently unaccounted execution time
+ * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
+ * list is used during load balance.
*/
- u64 load_avg;
- u64 load_period;
- u64 load_stamp, load_last, load_unacc_exec_time;
+ int on_list;
+ struct list_head leaf_cfs_rq_list;
+ struct task_group *tg; /* group that "owns" this runqueue */
- unsigned long load_contribution;
-#endif /* CONFIG_SMP */
#ifdef CONFIG_CFS_BANDWIDTH
int runtime_enabled;
u64 runtime_expires;
s64 runtime_remaining;
- u64 throttled_timestamp;
+ u64 throttled_clock, throttled_clock_task;
+ u64 throttled_clock_task_time;
int throttled, throttle_count;
struct list_head throttled_list;
#endif /* CONFIG_CFS_BANDWIDTH */
@@ -467,6 +480,8 @@ struct rq {
#ifdef CONFIG_SMP
struct llist_head wake_list;
#endif
+
+ struct sched_avg avg;
};
static inline int cpu_of(struct rq *rq)
@@ -1212,4 +1227,3 @@ static inline u64 irq_time_read(int cpu)
}
#endif /* CONFIG_64BIT */
#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
-
diff --git a/kernel/softirq.c b/kernel/softirq.c
index cc96bdc0c2c9..ed567babe789 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -221,7 +221,7 @@ asmlinkage void __do_softirq(void)
current->flags &= ~PF_MEMALLOC;
pending = local_softirq_pending();
- vtime_account(current);
+ vtime_account_irq_enter(current);
__local_bh_disable((unsigned long)__builtin_return_address(0),
SOFTIRQ_OFFSET);
@@ -272,7 +272,7 @@ restart:
lockdep_softirq_exit();
- vtime_account(current);
+ vtime_account_irq_exit(current);
__local_bh_enable(SOFTIRQ_OFFSET);
tsk_restore_flags(current, old_flags, PF_MEMALLOC);
}
@@ -341,7 +341,7 @@ static inline void invoke_softirq(void)
*/
void irq_exit(void)
{
- vtime_account(current);
+ vtime_account_irq_exit(current);
trace_hardirq_exit();
sub_preempt_count(IRQ_EXIT_OFFSET);
if (!in_interrupt() && local_softirq_pending())
diff --git a/kernel/sys.c b/kernel/sys.c
index e6e0ece5f6a0..265b37690421 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1046,7 +1046,7 @@ void do_sys_times(struct tms *tms)
cputime_t tgutime, tgstime, cutime, cstime;
spin_lock_irq(&current->sighand->siglock);
- thread_group_times(current, &tgutime, &tgstime);
+ thread_group_cputime_adjusted(current, &tgutime, &tgstime);
cutime = current->signal->cutime;
cstime = current->signal->cstime;
spin_unlock_irq(&current->sighand->siglock);
@@ -1704,7 +1704,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
utime = stime = 0;
if (who == RUSAGE_THREAD) {
- task_times(current, &utime, &stime);
+ task_cputime_adjusted(current, &utime, &stime);
accumulate_thread_rusage(p, r);
maxrss = p->signal->maxrss;
goto out;
@@ -1730,7 +1730,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
break;
case RUSAGE_SELF:
- thread_group_times(p, &tgutime, &tgstime);
+ thread_group_cputime_adjusted(p, &tgutime, &tgstime);
utime += tgutime;
stime += tgstime;
r->ru_nvcsw += p->signal->nvcsw;
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-19 09:24:10 +0100