irq_start_time 60 kernel/sched/cputime.c delta = sched_clock_cpu(cpu) - irqtime->irq_start_time; irq_start_time 61 kernel/sched/cputime.c irqtime->irq_start_time += delta; irq_start_time 2253 kernel/sched/sched.h u64 irq_start_time;