// SPDX-License-Identifier: GPL-2.0-only
/*
* Simple CPU accounting cgroup controller
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
#include <asm/cputime.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;
}
static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
enum cpu_usage_stat idx)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
u64_stats_update_begin(&irqtime->sync);
cpustat[idx] += delta;
irqtime->total += delta;
irqtime->tick_delta += delta;
u64_stats_update_end(&irqtime->sync);
}
/*
* Called after 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 int offset)
{
struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
unsigned int pc;
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;
pc = irq_count() - offset;
/*
* 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 (pc & HARDIRQ_MASK)
irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
else if ((pc & SOFTIRQ_OFFSET) && curr != this_cpu_ksoftirqd())
irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
}
static u64 irqtime_tick_accounted(u64 maxtime)
{
struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
u64 delta;
delta = min(irqtime->tick_delta, maxtime);
irqtime->tick_delta -= delta;
return delta;
}
#else /* CONFIG_IRQ_TIME_ACCOUNTING */
#define sched_clock_irqtime (0)
static u64 irqtime_tick_accounted(u64 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);
cgroup_account_cputime_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
*/
void account_user_time(struct task_struct *p, u64 cputime)
{
int index;
/* Add user time to process. */
p->utime += cputime;
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, 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
*/
void account_guest_time(struct task_struct *p, u64 cputime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
/* Add guest time to process. */
p->utime += cputime;
account_group_user_time(p, cputime);
p->gtime += cputime;
/* Add guest time to cpustat. */
if (task_nice(p) > 0) {
task_group_account_field(p, CPUTIME_NICE, cputime);
cpustat[CPUTIME_GUEST_NICE] += cputime;
} else {
task_group_account_field(p, CPUTIME_USER, cputime);
cpustat[CPUTIME_GUEST] += 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
* @index: pointer to cpustat field that has to be updated
*/
void account_system_index_time(struct task_struct *p,
u64 cputime, enum cpu_usage_stat index)
{
/* Add system time to process. */
p->stime += cputime;
account_group_system_time(p, cputime);
/* Add system time to cpustat. */
task_group_account_field(p, index, 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
*/
void account_system_time(struct task_struct *p, int hardirq_offset, u64 cputime)
{
int index;
if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
account_guest_time(p, cputime);
return;
}
if (hardirq_count() - hardirq_offset)
index = CPUTIME_IRQ;
else if (in_serving_softirq())
index = CPUTIME_SOFTIRQ;
else
index = CPUTIME_SYSTEM;
account_system_index_time(p, cputime, index);
}
/*
* Account for involuntary wait time.
* @cputime: the CPU time spent in involuntary wait
*/
void account_steal_time(u64 cputime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
cpustat[CPUTIME_STEAL] += cputime;
}
/*
* Account for idle time.
* @cputime: the CPU time spent in idle wait
*/
void account_idle_time(u64 cputime)
{
u64 *cpustat = kcpustat_this_cpu->cpustat;
struct rq *rq = this_rq();
if (atomic_read(&rq->nr_iowait) > 0)
cpustat[CPUTIME_IOWAIT] += cputime;
else
cpustat[CPUTIME_IDLE] += cputime;
}
#ifdef CONFIG_SCHED_CORE
/*
* Account for forceidle time due to core scheduling.
*
* REQUIRES: schedstat is enabled.
*/
void __account_forceidle_time(struct task_struct *p, u64 delta)
{
__schedstat_add(p->stats.core_forceidle_sum, delta);
task_group_account_field(p, CPUTIME_FORCEIDLE, delta);
}
#endif
/*
* 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 u64 steal_account_process_time(u64 maxtime)
{
#ifdef CONFIG_PARAVIRT
if (static_key_false(¶virt_steal_enabled)) {
u64 steal;
steal = paravirt_steal_clock(smp_processor_id());
steal -= this_rq()->prev_steal_time;
steal = min(steal, maxtime);
account_steal_time(steal);
this_rq()->prev_steal_time += steal;
return steal;
}
#endif
return 0;
}
/*
* Account how much elapsed time was spent in steal, IRQ, or softirq time.
*/
static inline u64 account_other_time(u64 max)
{
u64 accounted;
lockdep_assert_irqs_disabled();
accounted = steal_account_process_time(max);
if (accounted < max)
accounted += irqtime_tick_accounted(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;
u64 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,
int ticks)
{
u64 other, cputime = TICK_NSEC * ticks;
/*
* 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;
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_index_time(p, cputime, CPUTIME_SOFTIRQ);
} else if (user_tick) {
account_user_time(p, cputime);
} else if (p == this_rq()->idle) {
account_idle_time(cputime);
} else if (p->flags & PF_VCPU) { /* System time or guest time */
account_guest_time(p, cputime);
} else {
account_system_index_time(p, cputime, CPUTIME_SYSTEM);
}
}
static void irqtime_account_idle_ticks(int ticks)
{
irqtime_account_process_tick(current, 0, 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,
int nr_ticks) { }
#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
/*
* Use precise platform statistics if available:
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
void vtime_account_irq(struct task_struct *tsk, unsigned int offset)
{
unsigned int pc = irq_count() - offset;
if (pc & HARDIRQ_OFFSET) {
vtime_account_hardirq(tsk);
} else if (pc & SOFTIRQ_OFFSET) {
vtime_account_softirq(tsk);
} else if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) &&
is_idle_task(tsk)) {
vtime_account_idle(tsk);
} else {
vtime_account_kernel(tsk);
}
}
void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
u64 *ut, u64 *st)
{
*ut = curr->utime;
*st = curr->stime;
}
void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
{
*ut = p->utime;
*st = p->stime;
}
EXPORT_SYMBOL_GPL(task_cputime_adjusted);
void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *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)
{
u64 cputime, steal;
if (vtime_accounting_enabled_this_cpu())
return;
if (sched_clock_irqtime) {
irqtime_account_process_tick(p, user_tick, 1);
return;
}
cputime = TICK_NSEC;
steal = steal_account_process_time(ULONG_MAX);
if (steal >= cputime)
return;
cputime -= steal;
if (user_tick)
account_user_time(p, cputime);
else if ((p != this_rq()->idle) || (irq_count() != HARDIRQ_OFFSET))
account_system_time(p, HARDIRQ_OFFSET, cputime);
else
account_idle_time(cputime);
}
/*
* Account multiple ticks of idle time.
* @ticks: number of stolen ticks
*/
void account_idle_ticks(unsigned long ticks)
{
u64 cputime, steal;
if (sched_clock_irqtime) {
irqtime_account_idle_ticks(ticks);
return;
}
cputime = ticks * TICK_NSEC;
steal = steal_account_process_time(ULONG_MAX);
if (steal >= cputime)
return;
cputime -= steal;
account_idle_time(cputime);
}
/*
* 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.
*/
void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
u64 *ut, u64 *st)
{
u64 rtime, stime, utime;
unsigned long flags;
/* Serialize concurrent callers such that we can honour our guarantees */
raw_spin_lock_irqsave(&prev->lock, flags);
rtime = 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 utime are 0, assume all runtime is userspace.
* Once a task gets some ticks, the monotonicity 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 = mul_u64_u64_div_u64(stime, rtime, stime + utime);
/*
* Because mul_u64_u64_div_u64() can approximate on some
* achitectures; enforce the constraint that: a*b/(b+c) <= a.
*/
if (unlikely(stime > rtime))
stime = rtime;
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, u64 *ut, u64 *st)
{
struct task_cputime cputime = {
.sum_exec_runtime = p->se.sum_exec_runtime,
};
if (task_cputime(p, &cputime.utime, &cputime.stime))
cputime.sum_exec_runtime = task_sched_runtime(p);
cputime_adjust(&cputime, &p->prev_cputime, ut, st);
}
EXPORT_SYMBOL_GPL(task_cputime_adjusted);
void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *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 u64 vtime_delta(struct vtime *vtime)
{
unsigned long long clock;
clock = sched_clock();
if (clock < vtime->starttime)
return 0;
return clock - vtime->starttime;
}
static u64 get_vtime_delta(struct vtime *vtime)
{
u64 delta = vtime_delta(vtime);
u64 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.
*/
other = account_other_time(delta);
WARN_ON_ONCE(vtime->state == VTIME_INACTIVE);
vtime->starttime += delta;
return delta - other;
}
static void vtime_account_system(struct task_struct *tsk,
struct vtime *vtime)
{
vtime->stime += get_vtime_delta(vtime);
if (vtime->stime >= TICK_NSEC) {
account_system_time(tsk, irq_count(), vtime->stime);
vtime->stime = 0;
}
}
static void vtime_account_guest(struct task_struct *tsk,
struct vtime *vtime)
{
vtime->gtime += get_vtime_delta(vtime);
if (vtime->gtime >= TICK_NSEC) {
account_guest_time(tsk, vtime->gtime);
vtime->gtime = 0;
}
}
static void __vtime_account_kernel(struct task_struct *tsk,
struct vtime *vtime)
{
/* We might have scheduled out from guest path */
if (vtime->state == VTIME_GUEST)
vtime_account_guest(tsk, vtime);
else
vtime_account_system(tsk, vtime);
}
void vtime_account_kernel(struct task_struct *tsk)
{
struct vtime *vtime = &tsk->vtime;
if (!vtime_delta(vtime))
return;
write_seqcount_begin(&vtime->seqcount);
__vtime_account_kernel(tsk, vtime);
write_seqcount_end(&vtime->seqcount);
}
void vtime_user_enter(struct task_struct *tsk)
{
struct vtime *vtime = &tsk->vtime;
write_seqcount_begin(&vtime->seqcount);
vtime_account_system(tsk, vtime);
vtime->state = VTIME_USER;
write_seqcount_end(&vtime->seqcount);
}
void vtime_user_exit(struct task_struct *tsk)
{
struct vtime *vtime = &tsk->vtime;
write_seqcount_begin(&vtime->seqcount);
vtime->utime += get_vtime_delta(vtime);
if (vtime->utime >= TICK_NSEC) {
account_user_time(tsk, vtime->utime);
vtime->utime = 0;
}
vtime->state = VTIME_SYS;
write_seqcount_end(&vtime->seqcount);
}
void vtime_guest_enter(struct task_struct *tsk)
{
struct vtime *vtime = &tsk->vtime;
/*
* The flags must be updated under the lock with
* the vtime_starttime 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(&vtime->seqcount);
vtime_account_system(tsk, vtime);
tsk->flags |= PF_VCPU;
vtime->state = VTIME_GUEST;
write_seqcount_end(&vtime->seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_enter);
void vtime_guest_exit(struct task_struct *tsk)
{
struct vtime *vtime = &tsk->vtime;
write_seqcount_begin(&vtime->seqcount);
vtime_account_guest(tsk, vtime);
tsk->flags &= ~PF_VCPU;
vtime->state = VTIME_SYS;
write_seqcount_end(&vtime->seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_exit);
void vtime_account_idle(struct task_struct *tsk)
{
account_idle_time(get_vtime_delta(&tsk->vtime));
}
void vtime_task_switch_generic(struct task_struct *prev)
{
struct vtime *vtime = &prev->vtime;
write_seqcount_begin(&vtime->seqcount);
if (vtime->state == VTIME_IDLE)
vtime_account_idle(prev);
else
__vtime_account_kernel(prev, vtime);
vtime->state = VTIME_INACTIVE;
vtime->cpu = -1;
write_seqcount_end(&vtime->seqcount);
vtime = ¤t->vtime;
write_seqcount_begin(&vtime->seqcount);
if (is_idle_task(current))
vtime->state = VTIME_IDLE;
else if (current->flags & PF_VCPU)
vtime->state = VTIME_GUEST;
else
vtime->state = VTIME_SYS;
vtime->starttime = sched_clock();
vtime->cpu = smp_processor_id();
write_seqcount_end(&vtime->seqcount);
}
void vtime_init_idle(struct task_struct *t, int cpu)
{
struct vtime *vtime = &t->vtime;
unsigned long flags;
local_irq_save(flags);
write_seqcount_begin(&vtime->seqcount);
vtime->state = VTIME_IDLE;
vtime->starttime = sched_clock();
vtime->cpu = cpu;
write_seqcount_end(&vtime->seqcount);
local_irq_restore(flags);
}
u64 task_gtime(struct task_struct *t)
{
struct vtime *vtime = &t->vtime;
unsigned int seq;
u64 gtime;
if (!vtime_accounting_enabled())
return t->gtime;
do {
seq = read_seqcount_begin(&vtime->seqcount);
gtime = t->gtime;
if (vtime->state == VTIME_GUEST)
gtime += vtime->gtime + vtime_delta(vtime);
} while (read_seqcount_retry(&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.
*/
bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
{
struct vtime *vtime = &t->vtime;
unsigned int seq;
u64 delta;
int ret;
if (!vtime_accounting_enabled()) {
*utime = t->utime;
*stime = t->stime;
return false;
}
do {
ret = false;
seq = read_seqcount_begin(&vtime->seqcount);
*utime = t->utime;
*stime = t->stime;
/* Task is sleeping or idle, nothing to add */
if (vtime->state < VTIME_SYS)
continue;
ret = true;
delta = vtime_delta(vtime);
/*
* Task runs either in user (including guest) or kernel space,
* add pending nohz time to the right place.
*/
if (vtime->state == VTIME_SYS)
*stime += vtime->stime + delta;
else
*utime += vtime->utime + delta;
} while (read_seqcount_retry(&vtime->seqcount, seq));
return ret;
}
static int vtime_state_fetch(struct vtime *vtime, int cpu)
{
int state = READ_ONCE(vtime->state);
/*
* We raced against a context switch, fetch the
* kcpustat task again.
*/
if (vtime->cpu != cpu && vtime->cpu != -1)
return -EAGAIN;
/*
* Two possible things here:
* 1) We are seeing the scheduling out task (prev) or any past one.
* 2) We are seeing the scheduling in task (next) but it hasn't
* passed though vtime_task_switch() yet so the pending
* cputime of the prev task may not be flushed yet.
*
* Case 1) is ok but 2) is not. So wait for a safe VTIME state.
*/
if (state == VTIME_INACTIVE)
return -EAGAIN;
return state;
}
static u64 kcpustat_user_vtime(struct vtime *vtime)
{
if (vtime->state == VTIME_USER)
return vtime->utime + vtime_delta(vtime);
else if (vtime->state == VTIME_GUEST)
return vtime->gtime + vtime_delta(vtime);
return 0;
}
static int kcpustat_field_vtime(u64 *cpustat,
struct task_struct *tsk,
enum cpu_usage_stat usage,
int cpu, u64 *val)
{
struct vtime *vtime = &tsk->vtime;
unsigned int seq;
do {
int state;
seq = read_seqcount_begin(&vtime->seqcount);
state = vtime_state_fetch(vtime, cpu);
if (state < 0)
return state;
*val = cpustat[usage];
/*
* Nice VS unnice cputime accounting may be inaccurate if
* the nice value has changed since the last vtime update.
* But proper fix would involve interrupting target on nice
* updates which is a no go on nohz_full (although the scheduler
* may still interrupt the target if rescheduling is needed...)
*/
switch (usage) {
case CPUTIME_SYSTEM:
if (state == VTIME_SYS)
*val += vtime->stime + vtime_delta(vtime);
break;
case CPUTIME_USER:
if (task_nice(tsk) <= 0)
*val += kcpustat_user_vtime(vtime);
break;
case CPUTIME_NICE:
if (task_nice(tsk) > 0)
*val += kcpustat_user_vtime(vtime);
break;
case CPUTIME_GUEST:
if (state == VTIME_GUEST && task_nice(tsk) <= 0)
*val += vtime->gtime + vtime_delta(vtime);
break;
case CPUTIME_GUEST_NICE:
if (state == VTIME_GUEST && task_nice(tsk) > 0)
*val += vtime->gtime + vtime_delta(vtime);
break;
default:
break;
}
} while (read_seqcount_retry(&vtime->seqcount, seq));
return 0;
}
u64 kcpustat_field(struct kernel_cpustat *kcpustat,
enum cpu_usage_stat usage, int cpu)
{
u64 *cpustat = kcpustat->cpustat;
u64 val = cpustat[usage];
struct rq *rq;
int err;
if (!vtime_accounting_enabled_cpu(cpu))
return val;
rq = cpu_rq(cpu);
for (;;) {
struct task_struct *curr;
rcu_read_lock();
curr = rcu_dereference(rq->curr);
if (WARN_ON_ONCE(!curr)) {
rcu_read_unlock();
return cpustat[usage];
}
err = kcpustat_field_vtime(cpustat, curr, usage, cpu, &val);
rcu_read_unlock();
if (!err)
return val;
cpu_relax();
}
}
EXPORT_SYMBOL_GPL(kcpustat_field);
static int kcpustat_cpu_fetch_vtime(struct kernel_cpustat *dst,
const struct kernel_cpustat *src,
struct task_struct *tsk, int cpu)
{
struct vtime *vtime = &tsk->vtime;
unsigned int seq;
do {
u64 *cpustat;
u64 delta;
int state;
seq = read_seqcount_begin(&vtime->seqcount);
state = vtime_state_fetch(vtime, cpu);
if (state < 0)
return state;
*dst = *src;
cpustat = dst->cpustat;
/* Task is sleeping, dead or idle, nothing to add */
if (state < VTIME_SYS)
continue;
delta = vtime_delta(vtime);
/*
* Task runs either in user (including guest) or kernel space,
* add pending nohz time to the right place.
*/
if (state == VTIME_SYS) {
cpustat[CPUTIME_SYSTEM] += vtime->stime + delta;
} else if (state == VTIME_USER) {
if (task_nice(tsk) > 0)
cpustat[CPUTIME_NICE] += vtime->utime + delta;
else
cpustat[CPUTIME_USER] += vtime->utime + delta;
} else {
WARN_ON_ONCE(state != VTIME_GUEST);
if (task_nice(tsk) > 0) {
cpustat[CPUTIME_GUEST_NICE] += vtime->gtime + delta;
cpustat[CPUTIME_NICE] += vtime->gtime + delta;
} else {
cpustat[CPUTIME_GUEST] += vtime->gtime + delta;
cpustat[CPUTIME_USER] += vtime->gtime + delta;
}
}
} while (read_seqcount_retry(&vtime->seqcount, seq));
return 0;
}
void kcpustat_cpu_fetch(struct kernel_cpustat *dst, int cpu)
{
const struct kernel_cpustat *src = &kcpustat_cpu(cpu);
struct rq *rq;
int err;
if (!vtime_accounting_enabled_cpu(cpu)) {
*dst = *src;
return;
}
rq = cpu_rq(cpu);
for (;;) {
struct task_struct *curr;
rcu_read_lock();
curr = rcu_dereference(rq->curr);
if (WARN_ON_ONCE(!curr)) {
rcu_read_unlock();
*dst = *src;
return;
}
err = kcpustat_cpu_fetch_vtime(dst, src, curr, cpu);
rcu_read_unlock();
if (!err)
return;
cpu_relax();
}
}
EXPORT_SYMBOL_GPL(kcpustat_cpu_fetch);
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
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