Define __KERN_ORG__ inserted to differenciate between original scheduler and our...
[projects/modsched/linux.git] / kernel / sched / cputime.c
index 6b41146..e93cca9 100644 (file)
+#include <linux/export.h>
 #include <linux/sched.h>
+#include <linux/tsacct_kern.h>
 #include <linux/kernel_stat.h>
-
+#include <linux/static_key.h>
+#include <linux/context_tracking.h>
 #include "sched.h"
 
 
-struct kernel_cpustat *kcpustat;
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 
-void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+/*
+ * There are no locks covering percpu hardirq/softirq time.
+ * They are only modified in vtime_account, on corresponding CPU
+ * with interrupts disabled. So, writes are safe.
+ * They are read and saved off onto struct rq in update_rq_clock().
+ * This may result in other CPU reading this CPU's irq time and can
+ * race with irq/vtime_account on this CPU. We would either get old
+ * or new value with a side effect of accounting a slice of irq time to wrong
+ * task when irq is in progress while we read rq->clock. That is a worthy
+ * compromise in place of having locks on each irq in account_system_time.
+ */
+DEFINE_PER_CPU(u64, cpu_hardirq_time);
+DEFINE_PER_CPU(u64, cpu_softirq_time);
+
+static DEFINE_PER_CPU(u64, irq_start_time);
+static int sched_clock_irqtime;
+
+void enable_sched_clock_irqtime(void)
+{
+       sched_clock_irqtime = 1;
+}
+
+void disable_sched_clock_irqtime(void)
 {
-       return;
+       sched_clock_irqtime = 0;
+}
+
+#ifndef CONFIG_64BIT
+DEFINE_PER_CPU(seqcount_t, irq_time_seq);
+#endif /* CONFIG_64BIT */
+
+/*
+ * Called before incrementing preempt_count on {soft,}irq_enter
+ * and before decrementing preempt_count on {soft,}irq_exit.
+ */
+void irqtime_account_irq(struct task_struct *curr)
+{
+       unsigned long flags;
+       s64 delta;
+       int cpu;
+
+       if (!sched_clock_irqtime)
+               return;
+
+       local_irq_save(flags);
+
+       cpu = smp_processor_id();
+       delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
+       __this_cpu_add(irq_start_time, delta);
+
+       irq_time_write_begin();
+       /*
+        * We do not account for softirq time from ksoftirqd here.
+        * We want to continue accounting softirq time to ksoftirqd thread
+        * in that case, so as not to confuse scheduler with a special task
+        * that do not consume any time, but still wants to run.
+        */
+       if (hardirq_count())
+               __this_cpu_add(cpu_hardirq_time, delta);
+       else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
+               __this_cpu_add(cpu_softirq_time, delta);
+
+       irq_time_write_end();
+       local_irq_restore(flags);
+}
+EXPORT_SYMBOL_GPL(irqtime_account_irq);
+
+static int irqtime_account_hi_update(void)
+{
+       u64 *cpustat = kcpustat_this_cpu->cpustat;
+       unsigned long flags;
+       u64 latest_ns;
+       int ret = 0;
+
+       local_irq_save(flags);
+       latest_ns = this_cpu_read(cpu_hardirq_time);
+       if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
+               ret = 1;
+       local_irq_restore(flags);
+       return ret;
+}
+
+static int irqtime_account_si_update(void)
+{
+       u64 *cpustat = kcpustat_this_cpu->cpustat;
+       unsigned long flags;
+       u64 latest_ns;
+       int ret = 0;
+
+       local_irq_save(flags);
+       latest_ns = this_cpu_read(cpu_softirq_time);
+       if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
+               ret = 1;
+       local_irq_restore(flags);
+       return ret;
+}
+
+#else /* CONFIG_IRQ_TIME_ACCOUNTING */
+
+#define sched_clock_irqtime    (0)
+
+#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
+
+static inline void task_group_account_field(struct task_struct *p, int index,
+                                           u64 tmp)
+{
+#ifdef CONFIG_CGROUP_CPUACCT
+       struct kernel_cpustat *kcpustat;
+       struct cpuacct *ca;
+#endif
+       /*
+        * Since all updates are sure to touch the root cgroup, we
+        * get ourselves ahead and touch it first. If the root cgroup
+        * is the only cgroup, then nothing else should be necessary.
+        *
+        */
+       __get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
+
+#ifdef CONFIG_CGROUP_CPUACCT
+       if (unlikely(!cpuacct_subsys.active))
+               return;
+
+       rcu_read_lock();
+       ca = task_ca(p);
+       while (ca && (ca != &root_cpuacct)) {
+               kcpustat = this_cpu_ptr(ca->cpustat);
+               kcpustat->cpustat[index] += tmp;
+               ca = parent_ca(ca);
+       }
+       rcu_read_unlock();
+#endif
+}
+
+/*
+ * Account user cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in user space since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
+ */
+void account_user_time(struct task_struct *p, cputime_t cputime,
+                      cputime_t cputime_scaled)
+{
+       int index;
+
+       /* Add user time to process. */
+       p->utime += cputime;
+       p->utimescaled += cputime_scaled;
+       account_group_user_time(p, cputime);
+
+       index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
+
+       /* Add user time to cpustat. */
+       task_group_account_field(p, index, (__force u64) cputime);
+
+       /* Account for user time used */
+       acct_account_cputime(p);
+}
+
+/*
+ * Account guest cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in virtual machine since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
+ */
+static void account_guest_time(struct task_struct *p, cputime_t cputime,
+                              cputime_t cputime_scaled)
+{
+       u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+       /* Add guest time to process. */
+       p->utime += cputime;
+       p->utimescaled += cputime_scaled;
+       account_group_user_time(p, cputime);
+       p->gtime += cputime;
+
+       /* Add guest time to cpustat. */
+       if (TASK_NICE(p) > 0) {
+               cpustat[CPUTIME_NICE] += (__force u64) cputime;
+               cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
+       } else {
+               cpustat[CPUTIME_USER] += (__force u64) cputime;
+               cpustat[CPUTIME_GUEST] += (__force u64) cputime;
+       }
+}
+
+/*
+ * Account system cpu time to a process and desired cpustat field
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in kernel space since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
+ * @target_cputime64: pointer to cpustat field that has to be updated
+ */
+static inline
+void __account_system_time(struct task_struct *p, cputime_t cputime,
+                       cputime_t cputime_scaled, int index)
+{
+       /* Add system time to process. */
+       p->stime += cputime;
+       p->stimescaled += cputime_scaled;
+       account_group_system_time(p, cputime);
+
+       /* Add system time to cpustat. */
+       task_group_account_field(p, index, (__force u64) cputime);
+
+       /* Account for system time used */
+       acct_account_cputime(p);
+}
+
+/*
+ * Account system cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @hardirq_offset: the offset to subtract from hardirq_count()
+ * @cputime: the cpu time spent in kernel space since the last update
+ * @cputime_scaled: cputime scaled by cpu frequency
+ */
+void account_system_time(struct task_struct *p, int hardirq_offset,
+                        cputime_t cputime, cputime_t cputime_scaled)
+{
+       int index;
+
+       if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
+               account_guest_time(p, cputime, cputime_scaled);
+               return;
+       }
+
+       if (hardirq_count() - hardirq_offset)
+               index = CPUTIME_IRQ;
+       else if (in_serving_softirq())
+               index = CPUTIME_SOFTIRQ;
+       else
+               index = CPUTIME_SYSTEM;
+
+       __account_system_time(p, cputime, cputime_scaled, index);
+}
+
+/*
+ * Account for involuntary wait time.
+ * @cputime: the cpu time spent in involuntary wait
+ */
+void account_steal_time(cputime_t cputime)
+{
+       u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+       cpustat[CPUTIME_STEAL] += (__force u64) cputime;
+}
+
+/*
+ * Account for idle time.
+ * @cputime: the cpu time spent in idle wait
+ */
+void account_idle_time(cputime_t cputime)
+{
+       u64 *cpustat = kcpustat_this_cpu->cpustat;
+       struct rq *rq = this_rq();
+
+       if (atomic_read(&rq->nr_iowait) > 0)
+               cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
+       else
+               cpustat[CPUTIME_IDLE] += (__force u64) cputime;
+}
+
+static __always_inline bool steal_account_process_tick(void)
+{
+#ifdef CONFIG_PARAVIRT
+       if (static_key_false(&paravirt_steal_enabled)) {
+               u64 steal, st = 0;
+
+               steal = paravirt_steal_clock(smp_processor_id());
+               steal -= this_rq()->prev_steal_time;
+
+               st = steal_ticks(steal);
+               this_rq()->prev_steal_time += st * TICK_NSEC;
+
+               account_steal_time(st);
+               return st;
+       }
+#endif
+       return false;
 }
 
 /*
@@ -17,10 +295,523 @@ void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime
  */
 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 {
-       return;
+       struct signal_struct *sig = tsk->signal;
+       cputime_t utime, stime;
+       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 {
+               task_cputime(t, &utime, &stime);
+               times->utime += utime;
+               times->stime += stime;
+               times->sum_exec_runtime += task_sched_runtime(t);
+       } while_each_thread(tsk, t);
+out:
+       rcu_read_unlock();
+}
+
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+/*
+ * Account a tick to a process and cpustat
+ * @p: the process that the cpu time gets accounted to
+ * @user_tick: is the tick from userspace
+ * @rq: the pointer to rq
+ *
+ * Tick demultiplexing follows the order
+ * - pending hardirq update
+ * - pending softirq update
+ * - user_time
+ * - idle_time
+ * - system time
+ *   - check for guest_time
+ *   - else account as system_time
+ *
+ * Check for hardirq is done both for system and user time as there is
+ * no timer going off while we are on hardirq and hence we may never get an
+ * opportunity to update it solely in system time.
+ * p->stime and friends are only updated on system time and not on irq
+ * softirq as those do not count in task exec_runtime any more.
+ */
+static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
+                                               struct rq *rq)
+{
+       cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
+       u64 *cpustat = kcpustat_this_cpu->cpustat;
+
+       if (steal_account_process_tick())
+               return;
+
+       if (irqtime_account_hi_update()) {
+               cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy;
+       } else if (irqtime_account_si_update()) {
+               cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy;
+       } else if (this_cpu_ksoftirqd() == p) {
+               /*
+                * ksoftirqd time do not get accounted in cpu_softirq_time.
+                * So, we have to handle it separately here.
+                * Also, p->stime needs to be updated for ksoftirqd.
+                */
+               __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
+                                       CPUTIME_SOFTIRQ);
+       } else if (user_tick) {
+               account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
+       } else if (p == rq->idle) {
+               account_idle_time(cputime_one_jiffy);
+       } else if (p->flags & PF_VCPU) { /* System time or guest time */
+               account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
+       } else {
+               __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
+                                       CPUTIME_SYSTEM);
+       }
+}
+
+static void irqtime_account_idle_ticks(int ticks)
+{
+       int i;
+       struct rq *rq = this_rq();
+
+       for (i = 0; i < ticks; i++)
+               irqtime_account_process_tick(current, 0, rq);
+}
+#else /* CONFIG_IRQ_TIME_ACCOUNTING */
+static inline void irqtime_account_idle_ticks(int ticks) {}
+static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
+                                               struct rq *rq) {}
+#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
+
+#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+/*
+ * Account a single tick of cpu time.
+ * @p: the process that the cpu time gets accounted to
+ * @user_tick: indicates if the tick is a user or a system tick
+ */
+void account_process_tick(struct task_struct *p, int user_tick)
+{
+       cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
+       struct rq *rq = this_rq();
+
+       if (vtime_accounting_enabled())
+               return;
+
+       if (sched_clock_irqtime) {
+               irqtime_account_process_tick(p, user_tick, rq);
+               return;
+       }
+
+       if (steal_account_process_tick())
+               return;
+
+       if (user_tick)
+               account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
+       else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
+               account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
+                                   one_jiffy_scaled);
+       else
+               account_idle_time(cputime_one_jiffy);
 }
 
+/*
+ * Account multiple ticks of steal time.
+ * @p: the process from which the cpu time has been stolen
+ * @ticks: number of stolen ticks
+ */
+void account_steal_ticks(unsigned long ticks)
+{
+       account_steal_time(jiffies_to_cputime(ticks));
+}
+
+/*
+ * Account multiple ticks of idle time.
+ * @ticks: number of stolen ticks
+ */
+void account_idle_ticks(unsigned long ticks)
+{
+
+       if (sched_clock_irqtime) {
+               irqtime_account_idle_ticks(ticks);
+               return;
+       }
+
+       account_idle_time(jiffies_to_cputime(ticks));
+}
+#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
+
+/*
+ * Use precise platform statistics if available:
+ */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING
 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 {
-       return;
+       *ut = p->utime;
+       *st = p->stime;
+}
+
+void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+{
+       struct task_cputime cputime;
+
+       thread_group_cputime(p, &cputime);
+
+       *ut = cputime.utime;
+       *st = cputime.stime;
+}
+
+#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
+void vtime_task_switch(struct task_struct *prev)
+{
+       if (!vtime_accounting_enabled())
+               return;
+
+       if (is_idle_task(prev))
+               vtime_account_idle(prev);
+       else
+               vtime_account_system(prev);
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+       vtime_account_user(prev);
+#endif
+       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
+ * vtime_account_system() and vtime_account_idle(). Archs that
+ * have other meaning of the idle time (s390 only includes the
+ * time spent by the CPU when it's in low power mode) must override
+ * vtime_account().
+ */
+#ifndef __ARCH_HAS_VTIME_ACCOUNT
+void vtime_account_irq_enter(struct task_struct *tsk)
+{
+       if (!vtime_accounting_enabled())
+               return;
+
+       if (!in_interrupt()) {
+               /*
+                * If we interrupted user, context_tracking_in_user()
+                * is 1 because the context tracking don't hook
+                * on irq entry/exit. This way we know if
+                * we need to flush user time on kernel entry.
+                */
+               if (context_tracking_in_user()) {
+                       vtime_account_user(tsk);
+                       return;
+               }
+
+               if (is_idle_task(tsk)) {
+                       vtime_account_idle(tsk);
+                       return;
+               }
+       }
+       vtime_account_system(tsk);
+}
+EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
+#endif /* __ARCH_HAS_VTIME_ACCOUNT */
+
+#else /* !CONFIG_VIRT_CPU_ACCOUNTING */
+
+static cputime_t scale_stime(cputime_t stime, cputime_t rtime, cputime_t total)
+{
+       u64 temp = (__force u64) rtime;
+
+       temp *= (__force u64) stime;
+
+       if (sizeof(cputime_t) == 4)
+               temp = div_u64(temp, (__force u32) total);
+       else
+               temp = div64_u64(temp, (__force u64) total);
+
+       return (__force cputime_t) temp;
+}
+
+/*
+ * 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, stime, total;
+
+       stime = curr->stime;
+       total = stime + curr->utime;
+
+       /*
+        * 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(curr->sum_exec_runtime);
+
+       if (total)
+               stime = scale_stime(stime, rtime, total);
+       else
+               stime = rtime;
+
+       /*
+        * If the tick based count grows faster than the scheduler one,
+        * the result of the scaling may go backward.
+        * Let's enforce monotonicity.
+        */
+       prev->stime = max(prev->stime, stime);
+       prev->utime = max(prev->utime, rtime - 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 = {
+               .sum_exec_runtime = p->se.sum_exec_runtime,
+       };
+
+       task_cputime(p, &cputime.utime, &cputime.stime);
+       cputime_adjust(&cputime, &p->prev_cputime, ut, st);
+}
+
+/*
+ * Must be called with siglock held.
+ */
+void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+{
+       struct task_cputime cputime;
+
+       thread_group_cputime(p, &cputime);
+       cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
+}
+#endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
+static unsigned long long vtime_delta(struct task_struct *tsk)
+{
+       unsigned long long clock;
+
+       clock = local_clock();
+       if (clock < tsk->vtime_snap)
+               return 0;
+
+       return clock - tsk->vtime_snap;
+}
+
+static cputime_t get_vtime_delta(struct task_struct *tsk)
+{
+       unsigned long long delta = vtime_delta(tsk);
+
+       WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
+       tsk->vtime_snap += delta;
+
+       /* CHECKME: always safe to convert nsecs to cputime? */
+       return nsecs_to_cputime(delta);
+}
+
+static void __vtime_account_system(struct task_struct *tsk)
+{
+       cputime_t delta_cpu = get_vtime_delta(tsk);
+
+       account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
+}
+
+void vtime_account_system(struct task_struct *tsk)
+{
+       if (!vtime_accounting_enabled())
+               return;
+
+       write_seqlock(&tsk->vtime_seqlock);
+       __vtime_account_system(tsk);
+       write_sequnlock(&tsk->vtime_seqlock);
+}
+
+void vtime_account_irq_exit(struct task_struct *tsk)
+{
+       if (!vtime_accounting_enabled())
+               return;
+
+       write_seqlock(&tsk->vtime_seqlock);
+       if (context_tracking_in_user())
+               tsk->vtime_snap_whence = VTIME_USER;
+       __vtime_account_system(tsk);
+       write_sequnlock(&tsk->vtime_seqlock);
+}
+
+void vtime_account_user(struct task_struct *tsk)
+{
+       cputime_t delta_cpu;
+
+       if (!vtime_accounting_enabled())
+               return;
+
+       delta_cpu = get_vtime_delta(tsk);
+
+       write_seqlock(&tsk->vtime_seqlock);
+       tsk->vtime_snap_whence = VTIME_SYS;
+       account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
+       write_sequnlock(&tsk->vtime_seqlock);
+}
+
+void vtime_user_enter(struct task_struct *tsk)
+{
+       if (!vtime_accounting_enabled())
+               return;
+
+       write_seqlock(&tsk->vtime_seqlock);
+       tsk->vtime_snap_whence = VTIME_USER;
+       __vtime_account_system(tsk);
+       write_sequnlock(&tsk->vtime_seqlock);
+}
+
+void vtime_guest_enter(struct task_struct *tsk)
+{
+       write_seqlock(&tsk->vtime_seqlock);
+       __vtime_account_system(tsk);
+       current->flags |= PF_VCPU;
+       write_sequnlock(&tsk->vtime_seqlock);
+}
+
+void vtime_guest_exit(struct task_struct *tsk)
+{
+       write_seqlock(&tsk->vtime_seqlock);
+       __vtime_account_system(tsk);
+       current->flags &= ~PF_VCPU;
+       write_sequnlock(&tsk->vtime_seqlock);
+}
+
+void vtime_account_idle(struct task_struct *tsk)
+{
+       cputime_t delta_cpu = get_vtime_delta(tsk);
+
+       account_idle_time(delta_cpu);
+}
+
+bool vtime_accounting_enabled(void)
+{
+       return context_tracking_active();
+}
+
+void arch_vtime_task_switch(struct task_struct *prev)
+{
+       write_seqlock(&prev->vtime_seqlock);
+       prev->vtime_snap_whence = VTIME_SLEEPING;
+       write_sequnlock(&prev->vtime_seqlock);
+
+       write_seqlock(&current->vtime_seqlock);
+       current->vtime_snap_whence = VTIME_SYS;
+       current->vtime_snap = sched_clock();
+       write_sequnlock(&current->vtime_seqlock);
+}
+
+void vtime_init_idle(struct task_struct *t)
+{
+       unsigned long flags;
+
+       write_seqlock_irqsave(&t->vtime_seqlock, flags);
+       t->vtime_snap_whence = VTIME_SYS;
+       t->vtime_snap = sched_clock();
+       write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
+}
+
+cputime_t task_gtime(struct task_struct *t)
+{
+       unsigned int seq;
+       cputime_t gtime;
+
+       do {
+               seq = read_seqbegin(&t->vtime_seqlock);
+
+               gtime = t->gtime;
+               if (t->flags & PF_VCPU)
+                       gtime += vtime_delta(t);
+
+       } while (read_seqretry(&t->vtime_seqlock, seq));
+
+       return gtime;
+}
+
+/*
+ * Fetch cputime raw values from fields of task_struct and
+ * add up the pending nohz execution time since the last
+ * cputime snapshot.
+ */
+static void
+fetch_task_cputime(struct task_struct *t,
+                  cputime_t *u_dst, cputime_t *s_dst,
+                  cputime_t *u_src, cputime_t *s_src,
+                  cputime_t *udelta, cputime_t *sdelta)
+{
+       unsigned int seq;
+       unsigned long long delta;
+
+       do {
+               *udelta = 0;
+               *sdelta = 0;
+
+               seq = read_seqbegin(&t->vtime_seqlock);
+
+               if (u_dst)
+                       *u_dst = *u_src;
+               if (s_dst)
+                       *s_dst = *s_src;
+
+               /* Task is sleeping, nothing to add */
+               if (t->vtime_snap_whence == VTIME_SLEEPING ||
+                   is_idle_task(t))
+                       continue;
+
+               delta = vtime_delta(t);
+
+               /*
+                * Task runs either in user or kernel space, add pending nohz time to
+                * the right place.
+                */
+               if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
+                       *udelta = delta;
+               } else {
+                       if (t->vtime_snap_whence == VTIME_SYS)
+                               *sdelta = delta;
+               }
+       } while (read_seqretry(&t->vtime_seqlock, seq));
+}
+
+
+void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
+{
+       cputime_t udelta, sdelta;
+
+       fetch_task_cputime(t, utime, stime, &t->utime,
+                          &t->stime, &udelta, &sdelta);
+       if (utime)
+               *utime += udelta;
+       if (stime)
+               *stime += sdelta;
+}
+
+void task_cputime_scaled(struct task_struct *t,
+                        cputime_t *utimescaled, cputime_t *stimescaled)
+{
+       cputime_t udelta, sdelta;
+
+       fetch_task_cputime(t, utimescaled, stimescaled,
+                          &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
+       if (utimescaled)
+               *utimescaled += cputime_to_scaled(udelta);
+       if (stimescaled)
+               *stimescaled += cputime_to_scaled(sdelta);
 }
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */