Il 28/06/2013 04:57, Marcelo Tosatti ha scritto: > > One possibility for a softlockup report in a Linux VM, is that the host > system is overcommitted to the point where the watchdog task is unable > to make progress (unable to touch the watchdog). > > Maintain the increment in stolen time for the period of > softlockup threshold detection (20 seconds by the default), > and report this increment in the softlockup message. > > Overcommitment is then indicated by a large stolen time increment, > accounting for more than, or for a significant percentage of the > softlockup threshold. > > Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com> > > diff --git a/kernel/watchdog.c b/kernel/watchdog.c > index 05039e3..ed09d58 100644 > --- a/kernel/watchdog.c > +++ b/kernel/watchdog.c > @@ -34,6 +34,8 @@ int __read_mostly watchdog_thresh = 10; > static int __read_mostly watchdog_disabled; > static u64 __read_mostly sample_period; > > +#define SOFT_INTRS_PER_PERIOD 5 > + > static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); > static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); > static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); > @@ -127,9 +129,51 @@ static void set_sample_period(void) > * and hard thresholds) to increment before the > * hardlockup detector generates a warning > */ > - sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); > + sample_period = get_softlockup_thresh() * > + ((u64)NSEC_PER_SEC / SOFT_INTRS_PER_PERIOD); > } > > +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING > +struct steal_clock_record { > + u64 prev_stolen_time; > + u64 stolen_time[SOFT_INTRS_PER_PERIOD]; > + int idx; > +}; > + > +static DEFINE_PER_CPU(struct steal_clock_record, steal_record); > +static void record_steal_time(void) > +{ > + struct steal_clock_record *r; > + int cpu = smp_processor_id(); > + u64 steal_time; > + r = &per_cpu(steal_record, cpu); > + > + steal_time = paravirt_steal_clock(cpu); > + r->stolen_time[r->idx] = steal_time - r->prev_stolen_time; > + r->idx++; > + if (r->idx == SOFT_INTRS_PER_PERIOD) > + r->idx = 0; > + r->prev_stolen_time = steal_time; > +} > + > +static unsigned int get_accumulated_steal(int cpu) > +{ > + int idx; > + u64 t = 0; > + struct steal_clock_record *r = &per_cpu(steal_record, cpu); > + > + for (idx = 0; idx < SOFT_INTRS_PER_PERIOD; idx++) > + t += r->stolen_time[idx]; > + > + do_div(t, 1000000); > + > + return t; > +} > + > +#else > +static void record_steal_time(void) { return; } > +#endif > + > /* Commands for resetting the watchdog */ > static void __touch_watchdog(void) > { > @@ -271,6 +315,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct > hrtimer *hrtimer) > /* kick the hardlockup detector */ > watchdog_interrupt_count(); > > + /* record steal time */ > + record_steal_time(); > + > /* kick the softlockup detector */ > wake_up_process(__this_cpu_read(softlockup_watchdog)); > > @@ -316,6 +363,10 @@ static enum hrtimer_restart watchdog_timer_fn(struct > hrtimer *hrtimer) > printk(KERN_EMERG "BUG: soft lockup - CPU#%d stuck for %us! > [%s:%d]\n", > smp_processor_id(), duration, > current->comm, task_pid_nr(current)); > +#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING > + printk(KERN_EMERG "soft lockup stolen time = %ums\n", > + get_accumulated_steal(smp_processor_id()));
Perhaps print this only if nonzero (so that it doesn't print it on bare metal)? Then you can remove the #ifdef too, it will be optimized away by the compiler for !CONFIG_PARAVIRT_TIME_ACCOUNTING. Paolo > +#endif > print_modules(); > print_irqtrace_events(current); > if (regs) > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html