Messages in this thread | | | Date | Fri, 16 Apr 2010 10:12:13 -0400 | From | Don Zickus <> | Subject | Re: [PATCH v2] [watchdog] combine nmi_watchdog and softlockup |
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On Fri, Apr 16, 2010 at 03:47:14AM +0200, Frederic Weisbecker wrote: > On Thu, Apr 15, 2010 at 05:25:10PM -0400, Don Zickus wrote: > > The new nmi_watchdog (which uses the perf event subsystem) is very > > similar in structure to the softlockup detector. Using Ingo's suggestion, > > I combined the two functionalities into one file, kernel/watchdog.c. > > > > Now both the nmi_watchdog (or hardlockup detector) and softlockup detector > > sit on top of the perf event subsystem, which is run every 60 seconds or so > > to see if there are any lockups. > > > > To detect hardlockups, cpus not responding to interrupts, I implemented an > > hrtimer that runs 5 times for every perf event overflow event. If that stops > > counting on a cpu, then the cpu is most likely in trouble. > > > > To detect softlockups, tasks not yielding to the scheduler, I used the > > previous kthread idea that now gets kicked every time the hrtimer fires. > > If the kthread isn't being scheduled neither is anyone else and the > > warning is printed to the console. > > > > I tested this on x86_64 and both the softlockup and hardlockup paths work. > > > > V2: > > - cleaned up the Kconfig and softlockup combination > > - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI > > - seperated out the softlockup case from perf event subsystem > > - re-arranged the enabling/disabling nmi watchdog from proc space > > - added cpumasks for hardlockup failure cases > > - removed fallback to soft events if no PMU exists for hard events > > > > TODO: > > - figure out how to make an arch-agnostic clock2cycles call (if possible) > > to feed into perf events as a sample period > > > > In fact we also have the sample_freq thing that let you run > against a frequency (events per sec) rather than a sample > period. > > We do some calculations that recompute the actual sample > period on top of this frequency in a regular base as the > events come. > > It's rather unfortunate we can't have 0.xxxx frequencies > but may be we can work that out by adding a freq_unscale > field, which would basically produce the frequency like > this: > > freq = event->attr.sample_freq * (10 ^ -event->attr.freq_unscale) > > This is not trivial though, so let's rather focus on the > real matter for now :)
Interesting thanks.
> > > > diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c > > index e8b78a0..79425f9 100644 > > --- a/arch/x86/kernel/apic/hw_nmi.c > > +++ b/arch/x86/kernel/apic/hw_nmi.c > > @@ -89,7 +89,7 @@ int hw_nmi_is_cpu_stuck(struct pt_regs *regs) > > > > u64 hw_nmi_get_sample_period(void) > > { > > - return cpu_khz * 1000; > > + return (u64)(cpu_khz) * 1000 * 60; > > } > > > > #ifdef ARCH_HAS_NMI_WATCHDOG > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index 6f7bba9..83be6d7 100644 > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -338,6 +338,12 @@ extern int proc_dohung_task_timeout_secs(struct ctl_table *table, int write, > > size_t *lenp, loff_t *ppos); > > #endif > > > > +#ifdef CONFIG_NMI_WATCHDOG > > +extern int proc_dowatchdog_thresh(struct ctl_table *table, int write, > > + void __user *buffer, > > + size_t *lenp, loff_t *ppos); > > +#endif > > + > > /* Attach to any functions which should be ignored in wchan output. */ > > #define __sched __attribute__((__section__(".sched.text"))) > > > > diff --git a/init/Kconfig b/init/Kconfig > > index 7331a16..0b83612 100644 > > --- a/init/Kconfig > > +++ b/init/Kconfig > > @@ -948,6 +948,7 @@ config PERF_USE_VMALLOC > > > > config PERF_EVENTS_NMI > > bool > > + depends on PERF_EVENTS > > help > > Arch has support for nmi_watchdog > > > > That looks too general. It's more about the fact the arch supports > cpu cycle events and generates NMIs on overflow.
I was trying to figure out a way to add the PERF_EVENTS dependency as I didn't want to impose it on the CONFIG_NMI_WATCHDOG if that config supported softlockup (which doesn't need the PERF_EVENTS).
> > > > > diff --git a/kernel/Makefile b/kernel/Makefile > > index 8a5abe5..56ba99d 100644 > > --- a/kernel/Makefile > > +++ b/kernel/Makefile > > @@ -75,9 +75,11 @@ obj-$(CONFIG_GCOV_KERNEL) += gcov/ > > obj-$(CONFIG_AUDIT_TREE) += audit_tree.o > > obj-$(CONFIG_KPROBES) += kprobes.o > > obj-$(CONFIG_KGDB) += kgdb.o > > +ifneq ($(CONFIG_NMI_WATCHDOG),y) > > obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o > > -obj-$(CONFIG_NMI_WATCHDOG) += nmi_watchdog.o > > +endif > > > > I'm confused, do we have two versions of the softlockup > detector now? You should drop the older one.
Originally Ingo talked about a migration path, so I was going to support the older one in case the new one was having issues, sort of like what he suggested about moving the nmi code from arch/x86/kernel/apic/nmi.c to kernel/watchdog.c. But I can probably drop the softlockup case as the migration isn't as tricky as the nmi case.
> > > > > obj-$(CONFIG_DETECT_HUNG_TASK) += hung_task.o > > +obj-$(CONFIG_NMI_WATCHDOG) += watchdog.o > > obj-$(CONFIG_GENERIC_HARDIRQS) += irq/ > > obj-$(CONFIG_SECCOMP) += seccomp.o > > obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > > index ac72c9e..2165b22 100644 > > --- a/kernel/sysctl.c > > +++ b/kernel/sysctl.c > > @@ -704,6 +704,15 @@ static struct ctl_table kern_table[] = { > > .mode = 0644, > > .proc_handler = proc_nmi_enabled, > > }, > > + { > > + .procname = "watchdog_thresh", > > + .data = &softlockup_thresh, > > + .maxlen = sizeof(int), > > + .mode = 0644, > > + .proc_handler = proc_dowatchdog_thresh, > > + .extra1 = &neg_one, > > + .extra2 = &sixty, > > + }, > > #endif > > #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86) && !defined(CONFIG_NMI_WATCHDOG) > > { > > diff --git a/kernel/watchdog.c b/kernel/watchdog.c > > new file mode 100644 > > index 0000000..fad5b1a > > --- /dev/null > > +++ b/kernel/watchdog.c > > @@ -0,0 +1,570 @@ > > +/* > > + * Detect Hard/Soft Lockups using the NMI > > > > Well, softlockups detection doesn't use NMI.
Yeah, sorry. I dropped part of the code per your suggestion and forget to update the comments.
> > > > > +/* > > + * Returns seconds, approximately. We don't need nanosecond > > + * resolution, and we don't need to waste time with a big divide when > > + * 2^30ns == 1.074s. > > + */ > > +static unsigned long get_timestamp(int this_cpu) > > +{ > > + return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */ > > +} > > + > > +static unsigned long get_sample_period(void) > > +{ > > + /* > > + * convert softlockup_thresh from seconds to ns > > + * the divide by 5 is to give hrtimer 5 chances to > > + * increment before the hardlockup detector generates > > + * a warning > > + */ > > + return softlockup_thresh / 5 * NSEC_PER_SEC; > > +} > > + > > +/* Commands for resetting the watchdog */ > > +static void __touch_watchdog(void) > > +{ > > + int this_cpu = raw_smp_processor_id(); > > + > > + __raw_get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu); > > > > Please use __get_cpu_var() instead so that we keep the preempt disabled > check from smp_processor_id()
ok.
> > > > > +} > > + > > +void touch_watchdog(void) > > +{ > > + __raw_get_cpu_var(watchdog_touch_ts) = 0; > > > Same here. > > > > > +} > > +EXPORT_SYMBOL(touch_watchdog); > > + > > +void touch_all_watchdog(void) > > +{ > > + int cpu; > > + > > + for_each_online_cpu(cpu) > > + per_cpu(watchdog_touch_ts, cpu) = 0; > > +} > > + > > +/* deprecated functions */ > > +void touch_nmi_watchdog(void) > > +{ > > + touch_watchdog(); > > +} > > +EXPORT_SYMBOL(touch_nmi_watchdog); > > + > > +void touch_all_nmi_watchdog(void) > > +{ > > + touch_all_watchdog(); > > +} > > + > > +void touch_softlockup_watchdog(void) > > +{ > > + touch_watchdog(); > > +} > > + > > +void touch_all_softlockup_watchdogs(void) > > +{ > > + touch_all_watchdog(); > > +} > > + > > +void softlockup_tick(void) > > +{ > > +} > > +/* end of deprecated functions */ > > > > You should replace the call sites directly.
ok.
> > > > > +#ifdef CONFIG_PERF_EVENTS_NMI > > +/* watchdog detector functions */ > > +static int is_hardlockup(int cpu) > > +{ > > + unsigned long hrint = per_cpu(hrtimer_interrupts, cpu); > > + > > + if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint) > > + return 1; > > + > > + per_cpu(hrtimer_interrupts_saved, cpu) = hrint; > > + return 0; > > +} > > +#endif > > + > > +static int is_softlockup(unsigned long touch_ts, int cpu) > > +{ > > + unsigned long now = get_timestamp(cpu); > > + > > + /* Warn about unreasonable delays: */ > > + if (now > (touch_ts + softlockup_thresh)) > > + return now - touch_ts; > > + > > + return 0; > > +} > > + > > +static int > > +watchdog_panic(struct notifier_block *this, unsigned long event, void *ptr) > > +{ > > + did_panic = 1; > > + > > + return NOTIFY_DONE; > > +} > > + > > +static struct notifier_block panic_block = { > > + .notifier_call = watchdog_panic, > > +}; > > + > > +#ifdef CONFIG_PERF_EVENTS_NMI > > +struct perf_event_attr wd_hw_attr = { > > + .type = PERF_TYPE_HARDWARE, > > + .config = PERF_COUNT_HW_CPU_CYCLES, > > + .size = sizeof(struct perf_event_attr), > > + .pinned = 1, > > + .disabled = 1, > > +}; > > + > > +struct perf_event_attr wd_sw_attr = { > > + .type = PERF_TYPE_SOFTWARE, > > + .config = PERF_COUNT_SW_CPU_CLOCK, > > + .size = sizeof(struct perf_event_attr), > > + .pinned = 1, > > + .disabled = 1, > > +}; > > > > > Why do you keep the software clock, I don't see how it can be > useful to detect hardlockups. It triggers in a regular irq > not an NMI.
sorry, I dropped part of the code and forgot to drop this too.
> > > > > + > > +/* Callback function for perf event subsystem */ > > +void watchdog_overflow_callback(struct perf_event *event, int nmi, > > + struct perf_sample_data *data, > > + struct pt_regs *regs) > > +{ > > + int this_cpu = smp_processor_id(); > > + unsigned long touch_ts = per_cpu(watchdog_touch_ts, this_cpu); > > + > > + if (touch_ts == 0) { > > + __touch_watchdog(); > > + return; > > + } > > + > > + /* check for a hardlockup > > + * This is done by making sure our timer interrupt > > + * is incrementing. The timer interrupt should have > > + * fired multiple times before we overflow'd. If it hasn't > > + * then this is a good indication the cpu is stuck > > + */ > > + if (is_hardlockup(this_cpu)) { > > + /* only print hardlockups once */ > > + if (cpumask_test_cpu(this_cpu, to_cpumask(hardlockup_mask))) > > + return; > > + > > + if (hardlockup_panic) > > + panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu); > > + else > > + WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu); > > + > > + cpumask_set_cpu(this_cpu, to_cpumask(hardlockup_mask)); > > > > May be have an arch spin lock there to update your cpu mask safely.
ok.
> > > > > + return; > > + } > > + > > + cpumask_clear_cpu(this_cpu, to_cpumask(hardlockup_mask)); > > > > Hmm...this is probably not necessary.
I was just thinking of the case where dispite the WARN above, the cpu actually recovered and then failed again separately. But I probably won't spend anymore time defending it. :-)
> > > > > + return; > > +} > > +#endif /* CONFIG_PERF_EVENTS_NMI */ > > + > > +/* watchdog kicker functions */ > > +static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) > > +{ > > + int this_cpu = smp_processor_id(); > > + unsigned long touch_ts = per_cpu(watchdog_touch_ts, this_cpu); > > + struct pt_regs *regs = get_irq_regs(); > > + int duration; > > + > > +#ifdef CONFIG_PERF_EVENTS_NMI > > + /* kick the hardlockup detector */ > > + __get_cpu_var(hrtimer_interrupts)++; > > +#endif > > > > Please avoid such ifdefs in the middle of the code. > > It's better to gather hardlockup matters in a single ifdef block: > > #ifdef CONFIG_PERF_EVENTS_NMI > define your functions here > #else > define (if needed) your off case functions here (static inline stubs) > #endif
ok.
> > > > > + > > + /* kick the softlockup detector */ > > + wake_up_process(__get_cpu_var(softlockup_watchdog)); > > + > > + /* .. and repeat */ > > + hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period())); > > + > > + if (touch_ts == 0) { > > + __touch_watchdog(); > > + return HRTIMER_RESTART; > > + } > > + > > + /* check for a softlockup > > + * This is done by making sure a high priority task is > > + * being scheduled. The task touches the watchdog to > > + * indicate it is getting cpu time. If it hasn't then > > + * this is a good indication some task is hogging the cpu > > + */ > > + duration = is_softlockup(touch_ts, this_cpu); > > + if (duration) { > > + printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", > > + this_cpu, duration, > > + current->comm, task_pid_nr(current)); > > + print_modules(); > > + print_irqtrace_events(current); > > + if (regs) > > + show_regs(regs); > > + else > > + dump_stack(); > > + > > + if (softlockup_panic) > > + panic("softlockup: hung tasks"); > > > > You probably want a backtrace cpu mask here as well > (but better don't use the same than the hardlockup thing)
yup.
> > > > > + } > > + > > + return HRTIMER_RESTART; > > +} > > + > > + > > +/* > > + * The watchdog thread - touches the timestamp. > > + */ > > +static int watchdog(void *__bind_cpu) > > +{ > > + struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; > > + struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, (unsigned long)__bind_cpu); > > + > > + sched_setscheduler(current, SCHED_FIFO, ¶m); > > + > > + /* initialize timestamp */ > > + __touch_watchdog(); > > + > > + /* kick off the timer for the hardlockup detector */ > > + /* done here because hrtimer_start can only pin to smp_processor_id() */ > > + hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()), > > + HRTIMER_MODE_REL_PINNED); > > + > > + set_current_state(TASK_INTERRUPTIBLE); > > + /* > > + * Run briefly once per second to reset the softlockup timestamp. > > + * If this gets delayed for more than 60 seconds then the > > + * debug-printout triggers in softlockup_tick(). > > + */ > > + while (!kthread_should_stop()) { > > + __touch_watchdog(); > > + schedule(); > > + > > + if (kthread_should_stop()) > > + break; > > + > > + set_current_state(TASK_INTERRUPTIBLE); > > + } > > + __set_current_state(TASK_RUNNING); > > + > > + return 0; > > +} > > + > > + > > +/* prepare/enable/disable routines */ > > +static int watchdog_prepare_cpu(int cpu) > > +{ > > + struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu); > > + > > + BUG_ON(per_cpu(softlockup_watchdog, cpu)); > > > > Please warn here instead, nothing seriously dangerous is going to > happen. > > > > > + hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > > + hrtimer->function = watchdog_timer_fn; > > + > > + return 0; > > +} > > + > > +static int watchdog_enable(int cpu) > > +{ > > + struct task_struct *p = per_cpu(softlockup_watchdog, cpu); > > +#ifdef CONFIG_PERF_EVENTS_NMI > > + struct perf_event_attr *wd_attr; > > + struct perf_event *event = per_cpu(watchdog_ev, cpu); > > + > > + /* is it already setup and enabled? */ > > + if (event && event->state > PERF_EVENT_STATE_OFF) > > + goto out; > > + > > + /* it is setup but not enabled */ > > + if (event != NULL) > > + goto out_enable; > > + > > + /* Try to register using hardware perf events */ > > + wd_attr = &wd_hw_attr; > > + wd_attr->sample_period = hw_nmi_get_sample_period(); > > + event = perf_event_create_kernel_counter(wd_attr, cpu, -1, watchdog_overflow_callback); > > + if (!IS_ERR(event)) { > > + printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n"); > > + goto out_save; > > + } > > + > > + printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event); > > + return -1; > > + > > + /* success path */ > > +out_save: > > + per_cpu(watchdog_ev, cpu) = event; > > +out_enable: > > + perf_event_enable(per_cpu(watchdog_ev, cpu)); > > +out: > > +#endif /* CONFIG_PERF_EVENTS_NMI */ > > > > Especially such kind of idef in a function plus goto in the middle, we really > want to avoid that. > > You want a watchdog_nmi_enable() call instead that does nothing > if !CONFIG_PERF_EVENTS_NMI.
ok.
> > > > > + > > + /* create the watchdog thread */ > > + if (!p) { > > + p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu); > > + if (IS_ERR(p)) { > > + printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu); > > + return -1; > > + } > > + kthread_bind(p, cpu); > > + per_cpu(watchdog_touch_ts, cpu) = 0; > > + per_cpu(softlockup_watchdog, cpu) = p; > > + wake_up_process(p); > > + } > > + > > + return 0; > > +} > > + > > +static void watchdog_disable(int cpu) > > +{ > > + struct task_struct *p = per_cpu(softlockup_watchdog, cpu); > > + struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu); > > +#ifdef CONFIG_PERF_EVENTS_NMI > > + struct perf_event *event = per_cpu(watchdog_ev, cpu); > > +#endif > > + > > + /* > > + * cancel the timer first to stop incrementing the stats > > + * and waking up the kthread > > + */ > > + hrtimer_cancel(hrtimer); > > + > > +#ifdef CONFIG_PERF_EVENTS_NMI > > + if (event) { > > + perf_event_disable(event); > > + per_cpu(watchdog_ev, cpu) = NULL; > > + > > + /* should be in cleanup, but blocks oprofile */ > > + perf_event_release_kernel(event); > > + } > > +#endif > > + > > + if (p) { > > + per_cpu(softlockup_watchdog, cpu) = NULL; > > + kthread_stop(p); > > + } > > + > > + /* if any cpu succeeds, watchdog is considered enabled for the system */ > > + nmi_watchdog_enabled = 1; > > +} > > + > > +static void watchdog_cleanup(int cpu) > > +{ > > + > > +} > > + > > +static void watchdog_enable_all_cpus(void) > > +{ > > + int cpu; > > + int result; > > + > > + for_each_online_cpu(cpu) > > + result += watchdog_enable(cpu); > > + > > + if (result) > > + printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n"); > > + > > +} > > + > > +static void watchdog_disable_all_cpus(void) > > +{ > > + int cpu; > > + > > + for_each_online_cpu(cpu) > > + watchdog_disable(cpu); > > + > > + /* if all watchdogs are disabled, then they are disabled for the system */ > > + nmi_watchdog_enabled = 0; > > +} > > + > > + > > +/* sysctl functions */ > > +#ifdef CONFIG_SYSCTL > > +/* > > + * proc handler for /proc/sys/kernel/nmi_watchdog > > + */ > > + > > +int proc_nmi_enabled(struct ctl_table *table, int write, > > + void __user *buffer, size_t *length, loff_t *ppos) > > +{ > > + touch_all_watchdog(); > > > > Why do you need to touch watchdogs here?
just legacy stuff I copied over. I can remove.
> > > > > + proc_dointvec(table, write, buffer, length, ppos); > > + > > + if (nmi_watchdog_enabled) > > + watchdog_enable_all_cpus(); > > + else > > + watchdog_disable_all_cpus(); > > + return 0; > > +} > > + > > +int proc_dowatchdog_thresh(struct ctl_table *table, int write, > > + void __user *buffer, > > + size_t *lenp, loff_t *ppos) > > +{ > > + touch_all_watchdog(); > > > > Same here? > > > > + return proc_dointvec_minmax(table, write, buffer, lenp, ppos); > > +} > > + > > +/* stub functions */ > > +int proc_dosoftlockup_thresh(struct ctl_table *table, int write, > > + void __user *buffer, > > + size_t *lenp, loff_t *ppos) > > +{ > > + return proc_dowatchdog_thresh(table, write, buffer, lenp, ppos); > > +} > > +/* end of stub functions */ > > +#endif /* CONFIG_SYSCTL */ > > + > > + > > +/* > > + * Create/destroy watchdog threads as CPUs come and go: > > + */ > > +static int __cpuinit > > +cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) > > +{ > > + int hotcpu = (unsigned long)hcpu; > > + > > + switch (action) { > > + case CPU_UP_PREPARE: > > + case CPU_UP_PREPARE_FROZEN: > > + if (watchdog_prepare_cpu(hotcpu)) > > + return NOTIFY_BAD; > > + break; > > + case CPU_ONLINE: > > + case CPU_ONLINE_FROZEN: > > + if (watchdog_enable(hotcpu)) > > + return NOTIFY_BAD; > > + break; > > +#ifdef CONFIG_HOTPLUG_CPU > > + case CPU_UP_CANCELED: > > + case CPU_UP_CANCELED_FROZEN: > > + watchdog_disable(hotcpu); > > + break; > > + case CPU_DEAD: > > + case CPU_DEAD_FROZEN: > > + watchdog_disable(hotcpu); > > + watchdog_cleanup(hotcpu); > > + break; > > +#endif /* CONFIG_HOTPLUG_CPU */ > > + } > > + return NOTIFY_OK; > > +} > > + > > +static struct notifier_block __cpuinitdata cpu_nfb = { > > + .notifier_call = cpu_callback > > +}; > > + > > +static int __init spawn_watchdog_task(void) > > +{ > > + void *cpu = (void *)(long)smp_processor_id(); > > + int err; > > + > > + if (no_watchdog) > > + return 0; > > + > > + err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); > > + if (err == NOTIFY_BAD) { > > + BUG(); > > > > Please warn instead, there is nothing fatal here. > > > > > + return 1; > > + } > > + cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); > > + register_cpu_notifier(&cpu_nfb); > > + > > + atomic_notifier_chain_register(&panic_notifier_list, &panic_block); > > + > > + return 0; > > +} > > +early_initcall(spawn_watchdog_task); > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index e2e73cc..280794a 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -171,15 +171,24 @@ config DETECT_SOFTLOCKUP > > support it.) > > > > config NMI_WATCHDOG > > - bool "Detect Hard Lockups with an NMI Watchdog" > > - depends on DEBUG_KERNEL && PERF_EVENTS && PERF_EVENTS_NMI > > + bool "Detect Hard and Soft Lockups" > > + depends on DEBUG_KERNEL > > + default DETECT_SOFTLOCKUP > > > > I'd suggest to drop the NMI prefix, this is not anymore > about detecting hard lockups only. > > May be config WATCHDOG or config LOCKUP_DETECTOR if it's taken > already.
yeah, I thought about that too. Will work on it.
> > > Also you should half-drop the DETECT_SOFTLOCKUP thing: > keep it's definition but drop the ability to choose it from > the prompt: > > config DETECT_SOFTLOCKUP > bool > depends on DEBUG_KERNEL && !S390 > default y > > This way we keep it for compatibility with def_configs, it will > enable the WATCHDOG by default if it is "y", we can schedule > its removal later.
I understand the general idea but not quite the implementation idea. I will work on it and see what I come up with.
Thanks for the review!
Cheers, Don
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