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72298e5c92
Address a Coverity false positive, which is caused by overly convoluted code: Value assigned to variable 'utime' at line 619:utime = rtime; is overwritten at line 642:utime = rtime - stime; before it can be used. This makes such variable assignment useless. Remove this variable assignment and refactor the code related. Addresses-Coverity-ID: 1371643 Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Cc: Frans Klaver <fransklaver@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Link: http://lkml.kernel.org/r/20170629184128.GA5271@embeddedgus Signed-off-by: Ingo Molnar <mingo@kernel.org>
853 lines
22 KiB
C
853 lines
22 KiB
C
#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/tsacct_kern.h>
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#include <linux/kernel_stat.h>
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#include <linux/static_key.h>
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#include <linux/context_tracking.h>
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#include <linux/sched/cputime.h>
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#include "sched.h"
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#ifdef CONFIG_IRQ_TIME_ACCOUNTING
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/*
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* There are no locks covering percpu hardirq/softirq time.
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* They are only modified in vtime_account, on corresponding CPU
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* with interrupts disabled. So, writes are safe.
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* They are read and saved off onto struct rq in update_rq_clock().
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* This may result in other CPU reading this CPU's irq time and can
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* race with irq/vtime_account on this CPU. We would either get old
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* or new value with a side effect of accounting a slice of irq time to wrong
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* task when irq is in progress while we read rq->clock. That is a worthy
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* compromise in place of having locks on each irq in account_system_time.
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*/
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DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
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static int sched_clock_irqtime;
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void enable_sched_clock_irqtime(void)
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{
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sched_clock_irqtime = 1;
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}
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void disable_sched_clock_irqtime(void)
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{
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sched_clock_irqtime = 0;
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}
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static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
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enum cpu_usage_stat idx)
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{
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u64 *cpustat = kcpustat_this_cpu->cpustat;
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u64_stats_update_begin(&irqtime->sync);
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cpustat[idx] += delta;
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irqtime->total += delta;
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irqtime->tick_delta += delta;
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u64_stats_update_end(&irqtime->sync);
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}
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/*
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* Called before incrementing preempt_count on {soft,}irq_enter
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* and before decrementing preempt_count on {soft,}irq_exit.
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*/
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void irqtime_account_irq(struct task_struct *curr)
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{
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struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
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s64 delta;
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int cpu;
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if (!sched_clock_irqtime)
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return;
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cpu = smp_processor_id();
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delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
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irqtime->irq_start_time += delta;
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/*
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* We do not account for softirq time from ksoftirqd here.
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* We want to continue accounting softirq time to ksoftirqd thread
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* in that case, so as not to confuse scheduler with a special task
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* that do not consume any time, but still wants to run.
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*/
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if (hardirq_count())
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irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
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else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
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irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
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}
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EXPORT_SYMBOL_GPL(irqtime_account_irq);
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static u64 irqtime_tick_accounted(u64 maxtime)
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{
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struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
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u64 delta;
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delta = min(irqtime->tick_delta, maxtime);
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irqtime->tick_delta -= delta;
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return delta;
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}
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#else /* CONFIG_IRQ_TIME_ACCOUNTING */
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#define sched_clock_irqtime (0)
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static u64 irqtime_tick_accounted(u64 dummy)
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{
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return 0;
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}
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#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
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static inline void task_group_account_field(struct task_struct *p, int index,
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u64 tmp)
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{
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/*
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* Since all updates are sure to touch the root cgroup, we
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* get ourselves ahead and touch it first. If the root cgroup
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* is the only cgroup, then nothing else should be necessary.
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*
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*/
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__this_cpu_add(kernel_cpustat.cpustat[index], tmp);
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cpuacct_account_field(p, index, tmp);
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}
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/*
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* Account user cpu time to a process.
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* @p: the process that the cpu time gets accounted to
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* @cputime: the cpu time spent in user space since the last update
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*/
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void account_user_time(struct task_struct *p, u64 cputime)
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{
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int index;
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/* Add user time to process. */
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p->utime += cputime;
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account_group_user_time(p, cputime);
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index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
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/* Add user time to cpustat. */
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task_group_account_field(p, index, cputime);
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/* Account for user time used */
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acct_account_cputime(p);
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}
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/*
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* Account guest cpu time to a process.
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* @p: the process that the cpu time gets accounted to
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* @cputime: the cpu time spent in virtual machine since the last update
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*/
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void account_guest_time(struct task_struct *p, u64 cputime)
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{
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u64 *cpustat = kcpustat_this_cpu->cpustat;
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/* Add guest time to process. */
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p->utime += cputime;
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account_group_user_time(p, cputime);
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p->gtime += cputime;
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/* Add guest time to cpustat. */
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if (task_nice(p) > 0) {
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cpustat[CPUTIME_NICE] += cputime;
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cpustat[CPUTIME_GUEST_NICE] += cputime;
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} else {
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cpustat[CPUTIME_USER] += cputime;
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cpustat[CPUTIME_GUEST] += cputime;
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}
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}
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/*
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* Account system cpu time to a process and desired cpustat field
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* @p: the process that the cpu time gets accounted to
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* @cputime: the cpu time spent in kernel space since the last update
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* @index: pointer to cpustat field that has to be updated
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*/
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void account_system_index_time(struct task_struct *p,
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u64 cputime, enum cpu_usage_stat index)
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{
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/* Add system time to process. */
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p->stime += cputime;
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account_group_system_time(p, cputime);
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/* Add system time to cpustat. */
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task_group_account_field(p, index, cputime);
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/* Account for system time used */
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acct_account_cputime(p);
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}
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/*
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* Account system cpu time to a process.
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* @p: the process that the cpu time gets accounted to
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* @hardirq_offset: the offset to subtract from hardirq_count()
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* @cputime: the cpu time spent in kernel space since the last update
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*/
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void account_system_time(struct task_struct *p, int hardirq_offset, u64 cputime)
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{
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int index;
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if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
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account_guest_time(p, cputime);
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return;
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}
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if (hardirq_count() - hardirq_offset)
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index = CPUTIME_IRQ;
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else if (in_serving_softirq())
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index = CPUTIME_SOFTIRQ;
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else
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index = CPUTIME_SYSTEM;
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account_system_index_time(p, cputime, index);
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}
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/*
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* Account for involuntary wait time.
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* @cputime: the cpu time spent in involuntary wait
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*/
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void account_steal_time(u64 cputime)
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{
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u64 *cpustat = kcpustat_this_cpu->cpustat;
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cpustat[CPUTIME_STEAL] += cputime;
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}
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/*
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* Account for idle time.
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* @cputime: the cpu time spent in idle wait
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*/
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void account_idle_time(u64 cputime)
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{
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u64 *cpustat = kcpustat_this_cpu->cpustat;
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struct rq *rq = this_rq();
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if (atomic_read(&rq->nr_iowait) > 0)
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cpustat[CPUTIME_IOWAIT] += cputime;
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else
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cpustat[CPUTIME_IDLE] += cputime;
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}
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/*
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* When a guest is interrupted for a longer amount of time, missed clock
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* ticks are not redelivered later. Due to that, this function may on
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* occasion account more time than the calling functions think elapsed.
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*/
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static __always_inline u64 steal_account_process_time(u64 maxtime)
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{
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#ifdef CONFIG_PARAVIRT
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if (static_key_false(¶virt_steal_enabled)) {
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u64 steal;
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steal = paravirt_steal_clock(smp_processor_id());
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steal -= this_rq()->prev_steal_time;
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steal = min(steal, maxtime);
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account_steal_time(steal);
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this_rq()->prev_steal_time += steal;
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return steal;
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}
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#endif
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return 0;
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}
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/*
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* Account how much elapsed time was spent in steal, irq, or softirq time.
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*/
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static inline u64 account_other_time(u64 max)
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{
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u64 accounted;
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/* Shall be converted to a lockdep-enabled lightweight check */
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WARN_ON_ONCE(!irqs_disabled());
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accounted = steal_account_process_time(max);
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if (accounted < max)
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accounted += irqtime_tick_accounted(max - accounted);
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return accounted;
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}
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#ifdef CONFIG_64BIT
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static inline u64 read_sum_exec_runtime(struct task_struct *t)
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{
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return t->se.sum_exec_runtime;
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}
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#else
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static u64 read_sum_exec_runtime(struct task_struct *t)
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{
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u64 ns;
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struct rq_flags rf;
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struct rq *rq;
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rq = task_rq_lock(t, &rf);
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ns = t->se.sum_exec_runtime;
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task_rq_unlock(rq, t, &rf);
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return ns;
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}
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#endif
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/*
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* Accumulate raw cputime values of dead tasks (sig->[us]time) and live
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* tasks (sum on group iteration) belonging to @tsk's group.
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*/
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void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
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{
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struct signal_struct *sig = tsk->signal;
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u64 utime, stime;
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struct task_struct *t;
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unsigned int seq, nextseq;
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unsigned long flags;
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/*
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* Update current task runtime to account pending time since last
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* scheduler action or thread_group_cputime() call. This thread group
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* might have other running tasks on different CPUs, but updating
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* their runtime can affect syscall performance, so we skip account
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* those pending times and rely only on values updated on tick or
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* other scheduler action.
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*/
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if (same_thread_group(current, tsk))
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(void) task_sched_runtime(current);
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rcu_read_lock();
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/* Attempt a lockless read on the first round. */
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nextseq = 0;
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do {
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seq = nextseq;
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flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
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times->utime = sig->utime;
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times->stime = sig->stime;
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times->sum_exec_runtime = sig->sum_sched_runtime;
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for_each_thread(tsk, t) {
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task_cputime(t, &utime, &stime);
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times->utime += utime;
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times->stime += stime;
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times->sum_exec_runtime += read_sum_exec_runtime(t);
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}
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/* If lockless access failed, take the lock. */
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nextseq = 1;
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} while (need_seqretry(&sig->stats_lock, seq));
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done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
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rcu_read_unlock();
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}
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#ifdef CONFIG_IRQ_TIME_ACCOUNTING
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/*
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* Account a tick to a process and cpustat
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* @p: the process that the cpu time gets accounted to
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* @user_tick: is the tick from userspace
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* @rq: the pointer to rq
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*
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* Tick demultiplexing follows the order
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* - pending hardirq update
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* - pending softirq update
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* - user_time
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* - idle_time
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* - system time
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* - check for guest_time
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* - else account as system_time
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*
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* Check for hardirq is done both for system and user time as there is
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* no timer going off while we are on hardirq and hence we may never get an
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* opportunity to update it solely in system time.
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* p->stime and friends are only updated on system time and not on irq
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* softirq as those do not count in task exec_runtime any more.
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*/
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static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
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struct rq *rq, int ticks)
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{
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u64 other, cputime = TICK_NSEC * ticks;
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/*
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* When returning from idle, many ticks can get accounted at
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* once, including some ticks of steal, irq, and softirq time.
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* Subtract those ticks from the amount of time accounted to
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* idle, or potentially user or system time. Due to rounding,
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* other time can exceed ticks occasionally.
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*/
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other = account_other_time(ULONG_MAX);
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if (other >= cputime)
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return;
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cputime -= other;
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if (this_cpu_ksoftirqd() == p) {
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/*
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* ksoftirqd time do not get accounted in cpu_softirq_time.
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* So, we have to handle it separately here.
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* Also, p->stime needs to be updated for ksoftirqd.
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*/
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account_system_index_time(p, cputime, CPUTIME_SOFTIRQ);
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} else if (user_tick) {
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account_user_time(p, cputime);
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} else if (p == rq->idle) {
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account_idle_time(cputime);
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} else if (p->flags & PF_VCPU) { /* System time or guest time */
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account_guest_time(p, cputime);
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} else {
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account_system_index_time(p, cputime, CPUTIME_SYSTEM);
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}
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}
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static void irqtime_account_idle_ticks(int ticks)
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{
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struct rq *rq = this_rq();
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irqtime_account_process_tick(current, 0, rq, ticks);
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}
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#else /* CONFIG_IRQ_TIME_ACCOUNTING */
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static inline void irqtime_account_idle_ticks(int ticks) {}
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static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
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struct rq *rq, int nr_ticks) {}
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#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
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/*
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* Use precise platform statistics if available:
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*/
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#ifdef CONFIG_VIRT_CPU_ACCOUNTING
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#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
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void vtime_common_task_switch(struct task_struct *prev)
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{
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if (is_idle_task(prev))
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vtime_account_idle(prev);
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else
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vtime_account_system(prev);
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vtime_flush(prev);
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arch_vtime_task_switch(prev);
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}
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#endif
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#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
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#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
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/*
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* Archs that account the whole time spent in the idle task
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* (outside irq) as idle time can rely on this and just implement
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* vtime_account_system() and vtime_account_idle(). Archs that
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* have other meaning of the idle time (s390 only includes the
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* time spent by the CPU when it's in low power mode) must override
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* vtime_account().
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*/
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#ifndef __ARCH_HAS_VTIME_ACCOUNT
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void vtime_account_irq_enter(struct task_struct *tsk)
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{
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if (!in_interrupt() && is_idle_task(tsk))
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vtime_account_idle(tsk);
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else
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vtime_account_system(tsk);
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}
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EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
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#endif /* __ARCH_HAS_VTIME_ACCOUNT */
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void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
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{
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*ut = p->utime;
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*st = p->stime;
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}
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EXPORT_SYMBOL_GPL(task_cputime_adjusted);
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void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
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{
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struct task_cputime cputime;
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thread_group_cputime(p, &cputime);
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*ut = cputime.utime;
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*st = cputime.stime;
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}
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#else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
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/*
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* Account a single tick of cpu time.
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* @p: the process that the cpu time gets accounted to
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* @user_tick: indicates if the tick is a user or a system tick
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*/
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void account_process_tick(struct task_struct *p, int user_tick)
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{
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u64 cputime, steal;
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struct rq *rq = this_rq();
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if (vtime_accounting_cpu_enabled())
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return;
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if (sched_clock_irqtime) {
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irqtime_account_process_tick(p, user_tick, rq, 1);
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return;
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}
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cputime = TICK_NSEC;
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steal = steal_account_process_time(ULONG_MAX);
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if (steal >= cputime)
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return;
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cputime -= steal;
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if (user_tick)
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account_user_time(p, cputime);
|
|
else if ((p != 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);
|
|
}
|
|
|
|
/*
|
|
* Perform (stime * rtime) / total, but avoid multiplication overflow by
|
|
* loosing precision when the numbers are big.
|
|
*/
|
|
static u64 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 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,
|
|
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 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) {
|
|
if (utime == 0)
|
|
stime = rtime;
|
|
else
|
|
stime = scale_stime(stime, rtime, stime + utime);
|
|
}
|
|
|
|
/*
|
|
* 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,
|
|
};
|
|
|
|
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, 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 task_struct *tsk)
|
|
{
|
|
unsigned long now = READ_ONCE(jiffies);
|
|
|
|
if (time_before(now, (unsigned long)tsk->vtime_snap))
|
|
return 0;
|
|
|
|
return jiffies_to_nsecs(now - tsk->vtime_snap);
|
|
}
|
|
|
|
static u64 get_vtime_delta(struct task_struct *tsk)
|
|
{
|
|
unsigned long now = READ_ONCE(jiffies);
|
|
u64 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_nsecs(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)
|
|
{
|
|
account_system_time(tsk, irq_count(), get_vtime_delta(tsk));
|
|
}
|
|
|
|
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)
|
|
{
|
|
write_seqcount_begin(&tsk->vtime_seqcount);
|
|
tsk->vtime_snap_whence = VTIME_SYS;
|
|
if (vtime_delta(tsk))
|
|
account_user_time(tsk, get_vtime_delta(tsk));
|
|
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)
|
|
{
|
|
account_idle_time(get_vtime_delta(tsk));
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
u64 task_gtime(struct task_struct *t)
|
|
{
|
|
unsigned int seq;
|
|
u64 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.
|
|
*/
|
|
void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
|
|
{
|
|
u64 delta;
|
|
unsigned int seq;
|
|
|
|
if (!vtime_accounting_enabled()) {
|
|
*utime = t->utime;
|
|
*stime = t->stime;
|
|
return;
|
|
}
|
|
|
|
do {
|
|
seq = read_seqcount_begin(&t->vtime_seqcount);
|
|
|
|
*utime = t->utime;
|
|
*stime = t->stime;
|
|
|
|
/* 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)
|
|
*utime += delta;
|
|
else if (t->vtime_snap_whence == VTIME_SYS)
|
|
*stime += delta;
|
|
} while (read_seqcount_retry(&t->vtime_seqcount, seq));
|
|
}
|
|
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
|