On (21/07/16 14:34), Sergey Senozhatsky wrote: > > <IRQ> > apic_timer_interrupt() > smp_apic_timer_interrupt() > hrtimer_interrupt() > _raw_spin_lock_irqsave() > lock_acquire() > __lock_acquire() > sched_clock_cpu() > sched_clock() > kvm_sched_clock_read() > kvm_clock_read() > pvclock_clocksource_read() > pvclock_touch_watchdogs() > > Since this is VM and VCPU resume path, jiffies still maybe > be outdated here, which is often the case on my device. > pvclock_clocksource_read() clears PVCLOCK_GUEST_STOPPED, > touches watchdogs, but it uses stale jiffies: 4294740764 > (for example). Hmm, on the other hand, there is probably nothing that guarantees that the first watchdog hard IRQ we execute on a resuming VCPU is going to see updated jiffies, it still can use stale jiffies.
