diff options
| -rw-r--r-- | kernel/sched.c | 83 |
1 files changed, 50 insertions, 33 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index da14302a9857..79b557c63381 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -636,23 +636,18 @@ static inline struct task_group *task_group(struct task_struct *p) #endif /* CONFIG_CGROUP_SCHED */ -static u64 irq_time_cpu(int cpu); -static void sched_irq_time_avg_update(struct rq *rq, u64 irq_time); +static void update_rq_clock_task(struct rq *rq, s64 delta); -inline void update_rq_clock(struct rq *rq) +static void update_rq_clock(struct rq *rq) { - int cpu = cpu_of(rq); - u64 irq_time; + s64 delta; if (rq->skip_clock_update) return; - rq->clock = sched_clock_cpu(cpu); - irq_time = irq_time_cpu(cpu); - if (rq->clock - irq_time > rq->clock_task) - rq->clock_task = rq->clock - irq_time; - - sched_irq_time_avg_update(rq, irq_time); + delta = sched_clock_cpu(cpu_of(rq)) - rq->clock; + rq->clock += delta; + update_rq_clock_task(rq, delta); } /* @@ -1946,19 +1941,20 @@ void disable_sched_clock_irqtime(void) sched_clock_irqtime = 0; } -static u64 irq_time_cpu(int cpu) +static inline u64 irq_time_cpu(int cpu) { - if (!sched_clock_irqtime) - return 0; - return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu); } +/* + * Called before incrementing preempt_count on {soft,}irq_enter + * and before decrementing preempt_count on {soft,}irq_exit. + */ void account_system_vtime(struct task_struct *curr) { unsigned long flags; + s64 delta; int cpu; - u64 now, delta; if (!sched_clock_irqtime) return; @@ -1966,9 +1962,9 @@ void account_system_vtime(struct task_struct *curr) local_irq_save(flags); cpu = smp_processor_id(); - now = sched_clock_cpu(cpu); - delta = now - per_cpu(irq_start_time, cpu); - per_cpu(irq_start_time, cpu) = now; + delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time); + __this_cpu_add(irq_start_time, delta); + /* * We do not account for softirq time from ksoftirqd here. * We want to continue accounting softirq time to ksoftirqd thread @@ -1976,33 +1972,54 @@ void account_system_vtime(struct task_struct *curr) * that do not consume any time, but still wants to run. */ if (hardirq_count()) - per_cpu(cpu_hardirq_time, cpu) += delta; + __this_cpu_add(cpu_hardirq_time, delta); else if (in_serving_softirq() && !(curr->flags & PF_KSOFTIRQD)) - per_cpu(cpu_softirq_time, cpu) += delta; + __this_cpu_add(cpu_softirq_time, delta); local_irq_restore(flags); } EXPORT_SYMBOL_GPL(account_system_vtime); -static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) +static void update_rq_clock_task(struct rq *rq, s64 delta) { - if (sched_clock_irqtime && sched_feat(NONIRQ_POWER)) { - u64 delta_irq = curr_irq_time - rq->prev_irq_time; - rq->prev_irq_time = curr_irq_time; - sched_rt_avg_update(rq, delta_irq); - } + s64 irq_delta; + + irq_delta = irq_time_cpu(cpu_of(rq)) - rq->prev_irq_time; + + /* + * Since irq_time is only updated on {soft,}irq_exit, we might run into + * this case when a previous update_rq_clock() happened inside a + * {soft,}irq region. + * + * When this happens, we stop ->clock_task and only update the + * prev_irq_time stamp to account for the part that fit, so that a next + * update will consume the rest. This ensures ->clock_task is + * monotonic. + * + * It does however cause some slight miss-attribution of {soft,}irq + * time, a more accurate solution would be to update the irq_time using + * the current rq->clock timestamp, except that would require using + * atomic ops. + */ + if (irq_delta > delta) + irq_delta = delta; + + rq->prev_irq_time += irq_delta; + delta -= irq_delta; + rq->clock_task += delta; + + if (irq_delta && sched_feat(NONIRQ_POWER)) + sched_rt_avg_update(rq, irq_delta); } -#else +#else /* CONFIG_IRQ_TIME_ACCOUNTING */ -static u64 irq_time_cpu(int cpu) +static void update_rq_clock_task(struct rq *rq, s64 delta) { - return 0; + rq->clock_task += delta; } -static void sched_irq_time_avg_update(struct rq *rq, u64 curr_irq_time) { } - -#endif +#endif /* CONFIG_IRQ_TIME_ACCOUNTING */ #include "sched_idletask.c" #include "sched_fair.c" |