diff options
| -rw-r--r-- | kernel/sched.c | 51 |
1 files changed, 45 insertions, 6 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 79b557c..456c990 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1920,10 +1920,9 @@ static void deactivate_task(struct rq *rq, struct task_struct *p, int flags) * 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/account_system_vtime on this CPU. We would either get old - * or new value (or semi updated value on 32 bit) 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. + * 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. */ static DEFINE_PER_CPU(u64, cpu_hardirq_time); static DEFINE_PER_CPU(u64, cpu_softirq_time); @@ -1941,10 +1940,48 @@ void disable_sched_clock_irqtime(void) sched_clock_irqtime = 0; } -static inline u64 irq_time_cpu(int cpu) +#ifndef CONFIG_64BIT +static DEFINE_PER_CPU(seqcount_t, irq_time_seq); + +static inline void irq_time_write_begin(void) +{ + __this_cpu_inc(irq_time_seq.sequence); + smp_wmb(); +} + +static inline void irq_time_write_end(void) +{ + smp_wmb(); + __this_cpu_inc(irq_time_seq.sequence); +} + +static inline u64 irq_time_read(int cpu) +{ + u64 irq_time; + unsigned seq; + + do { + seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu)); + irq_time = per_cpu(cpu_softirq_time, cpu) + + per_cpu(cpu_hardirq_time, cpu); + } while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq)); + + return irq_time; +} +#else /* CONFIG_64BIT */ +static inline void irq_time_write_begin(void) +{ +} + +static inline void irq_time_write_end(void) +{ +} + +static inline u64 irq_time_read(int cpu) { return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu); } +#endif /* CONFIG_64BIT */ /* * Called before incrementing preempt_count on {soft,}irq_enter @@ -1965,6 +2002,7 @@ void account_system_vtime(struct task_struct *curr) delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time); __this_cpu_add(irq_start_time, delta); + irq_time_write_begin(); /* * We do not account for softirq time from ksoftirqd here. * We want to continue accounting softirq time to ksoftirqd thread @@ -1976,6 +2014,7 @@ void account_system_vtime(struct task_struct *curr) else if (in_serving_softirq() && !(curr->flags & PF_KSOFTIRQD)) __this_cpu_add(cpu_softirq_time, delta); + irq_time_write_end(); local_irq_restore(flags); } EXPORT_SYMBOL_GPL(account_system_vtime); @@ -1984,7 +2023,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta) { s64 irq_delta; - irq_delta = irq_time_cpu(cpu_of(rq)) - rq->prev_irq_time; + irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time; /* * Since irq_time is only updated on {soft,}irq_exit, we might run into |
