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Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull scheduler fix from Thomas Gleixner:
 "A single fix for a cputime accounting regression which got introduced
  in the 4.11 cycle"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cputime: Fix ksoftirqd cputime accounting regression
This commit is contained in:
Linus Torvalds 2017-04-30 11:35:00 -07:00
commit 14e07f023f
2 changed files with 23 additions and 13 deletions
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27
kernel/sched/cputime.c
View File

@ -34,6 +34,18 @@ 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 before incrementing preempt_count on {soft,}irq_enter
* and before decrementing preempt_count on {soft,}irq_exit.
@ -41,7 +53,6 @@ void disable_sched_clock_irqtime(void)
void irqtime_account_irq(struct task_struct *curr)
{
struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
u64 *cpustat = kcpustat_this_cpu->cpustat;
s64 delta;
int cpu;
@ -52,22 +63,16 @@ void irqtime_account_irq(struct task_struct *curr)
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()) {
cpustat[CPUTIME_IRQ] += delta;
irqtime->tick_delta += delta;
} else if (in_serving_softirq() && curr != this_cpu_ksoftirqd()) {
cpustat[CPUTIME_SOFTIRQ] += delta;
irqtime->tick_delta += delta;
}
u64_stats_update_end(&irqtime->sync);
if (hardirq_count())
irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
}
EXPORT_SYMBOL_GPL(irqtime_account_irq);

9
kernel/sched/sched.h
View File

@ -1869,6 +1869,7 @@ static inline void nohz_balance_exit_idle(unsigned int cpu) { }
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
struct irqtime {
u64 total;
u64 tick_delta;
u64 irq_start_time;
struct u64_stats_sync sync;
@ -1876,16 +1877,20 @@ struct irqtime {
DECLARE_PER_CPU(struct irqtime, cpu_irqtime);
/*
* Returns the irqtime minus the softirq time computed by ksoftirqd.
* Otherwise ksoftirqd's sum_exec_runtime is substracted its own runtime
* and never move forward.
*/
static inline u64 irq_time_read(int cpu)
{
struct irqtime *irqtime = &per_cpu(cpu_irqtime, cpu);
u64 *cpustat = kcpustat_cpu(cpu).cpustat;
unsigned int seq;
u64 total;
do {
seq = __u64_stats_fetch_begin(&irqtime->sync);
total = cpustat[CPUTIME_SOFTIRQ] + cpustat[CPUTIME_IRQ];
total = irqtime->total;
} while (__u64_stats_fetch_retry(&irqtime->sync, seq));
return total;