swh:1:snp:77163734605b0ec556b01d897b7bb4a7e30d46b6
Tip revision: 1001354ca34179f3db924eb66672442a173147dc authored by Linus Torvalds on 15 October 2016, 19:17:50 UTC
Linux 4.9-rc1
Linux 4.9-rc1
Tip revision: 1001354
cputime.c
#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"
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#endif
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
/*
* 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(struct irqtime, cpu_irqtime);
static int sched_clock_irqtime;
void enable_sched_clock_irqtime(void)
{
sched_clock_irqtime = 1;
}
void disable_sched_clock_irqtime(void)
{
sched_clock_irqtime = 0;
}
/*
* 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)
{
struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
s64 delta;
int cpu;
if (!sched_clock_irqtime)
return;
cpu = smp_processor_id();
delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
irqtime->irq_start_time += delta;
u64_stats_update_begin(&irqtime->sync);
/*
* 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())
irqtime->hardirq_time += delta;
else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
irqtime->softirq_time += delta;
u64_stats_update_end(&irqtime->sync);
}
EXPORT_SYMBOL_GPL(irqtime_account_irq);
static cputime_t irqtime_account_update(u64 irqtime, int idx, cputime_t maxtime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
cputime_t irq_cputime;
irq_cputime = nsecs_to_cputime64(irqtime) - cpustat[idx];
irq_cputime = min(irq_cputime, maxtime);
cpustat[idx] += irq_cputime;
return irq_cputime;
}
static cputime_t irqtime_account_hi_update(cputime_t maxtime)
{
return irqtime_account_update(__this_cpu_read(cpu_irqtime.hardirq_time),
CPUTIME_IRQ, maxtime);
}
static cputime_t irqtime_account_si_update(cputime_t maxtime)
{
return irqtime_account_update(__this_cpu_read(cpu_irqtime.softirq_time),
CPUTIME_SOFTIRQ, maxtime);
}
#else /* CONFIG_IRQ_TIME_ACCOUNTING */
#define sched_clock_irqtime (0)
static cputime_t irqtime_account_hi_update(cputime_t dummy)
{
return 0;
}
static cputime_t irqtime_account_si_update(cputime_t dummy)
{
return 0;
}
#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
static inline void task_group_account_field(struct task_struct *p, int index,
u64 tmp)
{
/*
* 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.
*
*/
__this_cpu_add(kernel_cpustat.cpustat[index], tmp);
cpuacct_account_field(p, index, tmp);
}
/*
* 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;
}
/*
* When a guest is interrupted for a longer amount of time, missed clock
* ticks are not redelivered later. Due to that, this function may on
* occasion account more time than the calling functions think elapsed.
*/
static __always_inline cputime_t steal_account_process_time(cputime_t maxtime)
{
#ifdef CONFIG_PARAVIRT
if (static_key_false(¶virt_steal_enabled)) {
cputime_t steal_cputime;
u64 steal;
steal = paravirt_steal_clock(smp_processor_id());
steal -= this_rq()->prev_steal_time;
steal_cputime = min(nsecs_to_cputime(steal), maxtime);
account_steal_time(steal_cputime);
this_rq()->prev_steal_time += cputime_to_nsecs(steal_cputime);
return steal_cputime;
}
#endif
return 0;
}
/*
* Account how much elapsed time was spent in steal, irq, or softirq time.
*/
static inline cputime_t account_other_time(cputime_t max)
{
cputime_t accounted;
/* Shall be converted to a lockdep-enabled lightweight check */
WARN_ON_ONCE(!irqs_disabled());
accounted = steal_account_process_time(max);
if (accounted < max)
accounted += irqtime_account_hi_update(max - accounted);
if (accounted < max)
accounted += irqtime_account_si_update(max - accounted);
return accounted;
}
#ifdef CONFIG_64BIT
static inline u64 read_sum_exec_runtime(struct task_struct *t)
{
return t->se.sum_exec_runtime;
}
#else
static u64 read_sum_exec_runtime(struct task_struct *t)
{
u64 ns;
struct rq_flags rf;
struct rq *rq;
rq = task_rq_lock(t, &rf);
ns = t->se.sum_exec_runtime;
task_rq_unlock(rq, t, &rf);
return ns;
}
#endif
/*
* 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;
cputime_t utime, stime;
struct task_struct *t;
unsigned int seq, nextseq;
unsigned long flags;
/*
* Update current task runtime to account pending time since last
* scheduler action or thread_group_cputime() call. This thread group
* might have other running tasks on different CPUs, but updating
* their runtime can affect syscall performance, so we skip account
* those pending times and rely only on values updated on tick or
* other scheduler action.
*/
if (same_thread_group(current, tsk))
(void) task_sched_runtime(current);
rcu_read_lock();
/* Attempt a lockless read on the first round. */
nextseq = 0;
do {
seq = nextseq;
flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
times->utime = sig->utime;
times->stime = sig->stime;
times->sum_exec_runtime = sig->sum_sched_runtime;
for_each_thread(tsk, t) {
task_cputime(t, &utime, &stime);
times->utime += utime;
times->stime += stime;
times->sum_exec_runtime += read_sum_exec_runtime(t);
}
/* If lockless access failed, take the lock. */
nextseq = 1;
} while (need_seqretry(&sig->stats_lock, seq));
done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
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, int ticks)
{
u64 cputime = (__force u64) cputime_one_jiffy * ticks;
cputime_t scaled, other;
/*
* When returning from idle, many ticks can get accounted at
* once, including some ticks of steal, irq, and softirq time.
* Subtract those ticks from the amount of time accounted to
* idle, or potentially user or system time. Due to rounding,
* other time can exceed ticks occasionally.
*/
other = account_other_time(ULONG_MAX);
if (other >= cputime)
return;
cputime -= other;
scaled = cputime_to_scaled(cputime);
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, scaled, CPUTIME_SOFTIRQ);
} else if (user_tick) {
account_user_time(p, cputime, scaled);
} else if (p == rq->idle) {
account_idle_time(cputime);
} else if (p->flags & PF_VCPU) { /* System time or guest time */
account_guest_time(p, cputime, scaled);
} else {
__account_system_time(p, cputime, scaled, CPUTIME_SYSTEM);
}
}
static void irqtime_account_idle_ticks(int ticks)
{
struct rq *rq = this_rq();
irqtime_account_process_tick(current, 0, rq, ticks);
}
#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, int nr_ticks) {}
#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
/*
* Use precise platform statistics if available:
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
void vtime_common_task_switch(struct task_struct *prev)
{
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
#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
/*
* 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 (!in_interrupt() && is_idle_task(tsk))
vtime_account_idle(tsk);
else
vtime_account_system(tsk);
}
EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
#endif /* __ARCH_HAS_VTIME_ACCOUNT */
void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
*ut = p->utime;
*st = p->stime;
}
EXPORT_SYMBOL_GPL(task_cputime_adjusted);
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;
}
#else /* !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 cputime, scaled, steal;
struct rq *rq = this_rq();
if (vtime_accounting_cpu_enabled())
return;
if (sched_clock_irqtime) {
irqtime_account_process_tick(p, user_tick, rq, 1);
return;
}
cputime = cputime_one_jiffy;
steal = steal_account_process_time(ULONG_MAX);
if (steal >= cputime)
return;
cputime -= steal;
scaled = cputime_to_scaled(cputime);
if (user_tick)
account_user_time(p, cputime, scaled);
else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
account_system_time(p, HARDIRQ_OFFSET, cputime, scaled);
else
account_idle_time(cputime);
}
/*
* Account multiple ticks of idle time.
* @ticks: number of stolen ticks
*/
void account_idle_ticks(unsigned long ticks)
{
cputime_t cputime, steal;
if (sched_clock_irqtime) {
irqtime_account_idle_ticks(ticks);
return;
}
cputime = jiffies_to_cputime(ticks);
steal = steal_account_process_time(ULONG_MAX);
if (steal >= cputime)
return;
cputime -= steal;
account_idle_time(cputime);
}
/*
* Perform (stime * rtime) / total, but avoid multiplication overflow by
* loosing precision when the numbers are big.
*/
static cputime_t scale_stime(u64 stime, u64 rtime, u64 total)
{
u64 scaled;
for (;;) {
/* Make sure "rtime" is the bigger of stime/rtime */
if (stime > rtime)
swap(rtime, stime);
/* Make sure 'total' fits in 32 bits */
if (total >> 32)
goto drop_precision;
/* Does rtime (and thus stime) fit in 32 bits? */
if (!(rtime >> 32))
break;
/* Can we just balance rtime/stime rather than dropping bits? */
if (stime >> 31)
goto drop_precision;
/* We can grow stime and shrink rtime and try to make them both fit */
stime <<= 1;
rtime >>= 1;
continue;
drop_precision:
/* We drop from rtime, it has more bits than stime */
rtime >>= 1;
total >>= 1;
}
/*
* Make sure gcc understands that this is a 32x32->64 multiply,
* followed by a 64/32->64 divide.
*/
scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
return (__force cputime_t) scaled;
}
/*
* Adjust tick based cputime random precision against scheduler runtime
* 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.
*
* This code provides the following guarantees:
*
* stime + utime == rtime
* stime_i+1 >= stime_i, utime_i+1 >= utime_i
*
* Assuming that rtime_i+1 >= rtime_i.
*/
static void cputime_adjust(struct task_cputime *curr,
struct prev_cputime *prev,
cputime_t *ut, cputime_t *st)
{
cputime_t rtime, stime, utime;
unsigned long flags;
/* Serialize concurrent callers such that we can honour our guarantees */
raw_spin_lock_irqsave(&prev->lock, flags);
rtime = nsecs_to_cputime(curr->sum_exec_runtime);
/*
* This is possible under two circumstances:
* - rtime isn't monotonic after all (a bug);
* - we got reordered by the lock.
*
* In both cases this acts as a filter such that the rest of the code
* can assume it is monotonic regardless of anything else.
*/
if (prev->stime + prev->utime >= rtime)
goto out;
stime = curr->stime;
utime = curr->utime;
/*
* If either stime or both stime and utime are 0, assume all runtime is
* userspace. Once a task gets some ticks, the monotonicy code at
* 'update' will ensure things converge to the observed ratio.
*/
if (stime == 0) {
utime = rtime;
goto update;
}
if (utime == 0) {
stime = rtime;
goto update;
}
stime = scale_stime((__force u64)stime, (__force u64)rtime,
(__force u64)(stime + utime));
update:
/*
* Make sure stime doesn't go backwards; this preserves monotonicity
* for utime because rtime is monotonic.
*
* utime_i+1 = rtime_i+1 - stime_i
* = rtime_i+1 - (rtime_i - utime_i)
* = (rtime_i+1 - rtime_i) + utime_i
* >= utime_i
*/
if (stime < prev->stime)
stime = prev->stime;
utime = rtime - stime;
/*
* Make sure utime doesn't go backwards; this still preserves
* monotonicity for stime, analogous argument to above.
*/
if (utime < prev->utime) {
utime = prev->utime;
stime = rtime - utime;
}
prev->stime = stime;
prev->utime = utime;
out:
*ut = prev->utime;
*st = prev->stime;
raw_spin_unlock_irqrestore(&prev->lock, flags);
}
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);
}
EXPORT_SYMBOL_GPL(task_cputime_adjusted);
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_NATIVE */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
static cputime_t vtime_delta(struct task_struct *tsk)
{
unsigned long now = READ_ONCE(jiffies);
if (time_before(now, (unsigned long)tsk->vtime_snap))
return 0;
return jiffies_to_cputime(now - tsk->vtime_snap);
}
static cputime_t get_vtime_delta(struct task_struct *tsk)
{
unsigned long now = READ_ONCE(jiffies);
cputime_t delta, other;
/*
* Unlike tick based timing, vtime based timing never has lost
* ticks, and no need for steal time accounting to make up for
* lost ticks. Vtime accounts a rounded version of actual
* elapsed time. Limit account_other_time to prevent rounding
* errors from causing elapsed vtime to go negative.
*/
delta = jiffies_to_cputime(now - tsk->vtime_snap);
other = account_other_time(delta);
WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
tsk->vtime_snap = now;
return delta - other;
}
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_delta(tsk))
return;
write_seqcount_begin(&tsk->vtime_seqcount);
__vtime_account_system(tsk);
write_seqcount_end(&tsk->vtime_seqcount);
}
void vtime_account_user(struct task_struct *tsk)
{
cputime_t delta_cpu;
write_seqcount_begin(&tsk->vtime_seqcount);
tsk->vtime_snap_whence = VTIME_SYS;
if (vtime_delta(tsk)) {
delta_cpu = get_vtime_delta(tsk);
account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
}
write_seqcount_end(&tsk->vtime_seqcount);
}
void vtime_user_enter(struct task_struct *tsk)
{
write_seqcount_begin(&tsk->vtime_seqcount);
if (vtime_delta(tsk))
__vtime_account_system(tsk);
tsk->vtime_snap_whence = VTIME_USER;
write_seqcount_end(&tsk->vtime_seqcount);
}
void vtime_guest_enter(struct task_struct *tsk)
{
/*
* The flags must be updated under the lock with
* the vtime_snap flush and update.
* That enforces a right ordering and update sequence
* synchronization against the reader (task_gtime())
* that can thus safely catch up with a tickless delta.
*/
write_seqcount_begin(&tsk->vtime_seqcount);
if (vtime_delta(tsk))
__vtime_account_system(tsk);
current->flags |= PF_VCPU;
write_seqcount_end(&tsk->vtime_seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_enter);
void vtime_guest_exit(struct task_struct *tsk)
{
write_seqcount_begin(&tsk->vtime_seqcount);
__vtime_account_system(tsk);
current->flags &= ~PF_VCPU;
write_seqcount_end(&tsk->vtime_seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_exit);
void vtime_account_idle(struct task_struct *tsk)
{
cputime_t delta_cpu = get_vtime_delta(tsk);
account_idle_time(delta_cpu);
}
void arch_vtime_task_switch(struct task_struct *prev)
{
write_seqcount_begin(&prev->vtime_seqcount);
prev->vtime_snap_whence = VTIME_INACTIVE;
write_seqcount_end(&prev->vtime_seqcount);
write_seqcount_begin(¤t->vtime_seqcount);
current->vtime_snap_whence = VTIME_SYS;
current->vtime_snap = jiffies;
write_seqcount_end(¤t->vtime_seqcount);
}
void vtime_init_idle(struct task_struct *t, int cpu)
{
unsigned long flags;
local_irq_save(flags);
write_seqcount_begin(&t->vtime_seqcount);
t->vtime_snap_whence = VTIME_SYS;
t->vtime_snap = jiffies;
write_seqcount_end(&t->vtime_seqcount);
local_irq_restore(flags);
}
cputime_t task_gtime(struct task_struct *t)
{
unsigned int seq;
cputime_t gtime;
if (!vtime_accounting_enabled())
return t->gtime;
do {
seq = read_seqcount_begin(&t->vtime_seqcount);
gtime = t->gtime;
if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU)
gtime += vtime_delta(t);
} while (read_seqcount_retry(&t->vtime_seqcount, 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_seqcount_begin(&t->vtime_seqcount);
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_INACTIVE ||
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_seqcount_retry(&t->vtime_seqcount, seq));
}
void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
{
cputime_t udelta, sdelta;
if (!vtime_accounting_enabled()) {
if (utime)
*utime = t->utime;
if (stime)
*stime = t->stime;
return;
}
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;
if (!vtime_accounting_enabled()) {
if (utimescaled)
*utimescaled = t->utimescaled;
if (stimescaled)
*stimescaled = t->stimescaled;
return;
}
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 */