diff options
Diffstat (limited to 'kernel/watchdog.c')
| -rw-r--r-- | kernel/watchdog.c | 57 |
1 files changed, 34 insertions, 23 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 140dce750450..7daa4b072e9f 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -28,7 +28,7 @@ #include <linux/perf_event.h> int watchdog_enabled = 1; -int __read_mostly softlockup_thresh = 60; +int __read_mostly watchdog_thresh = 10; static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); @@ -91,6 +91,17 @@ static int __init nosoftlockup_setup(char *str) __setup("nosoftlockup", nosoftlockup_setup); /* */ +/* + * Hard-lockup warnings should be triggered after just a few seconds. Soft- + * lockups can have false positives under extreme conditions. So we generally + * want a higher threshold for soft lockups than for hard lockups. So we couple + * the thresholds with a factor: we make the soft threshold twice the amount of + * time the hard threshold is. + */ +static int get_softlockup_thresh(void) +{ + return watchdog_thresh * 2; +} /* * Returns seconds, approximately. We don't need nanosecond @@ -105,12 +116,12 @@ static unsigned long get_timestamp(int this_cpu) static unsigned long get_sample_period(void) { /* - * convert softlockup_thresh from seconds to ns + * convert watchdog_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; + return get_softlockup_thresh() * (NSEC_PER_SEC / 5); } /* Commands for resetting the watchdog */ @@ -182,7 +193,7 @@ static int is_softlockup(unsigned long touch_ts) unsigned long now = get_timestamp(smp_processor_id()); /* Warn about unreasonable delays: */ - if (time_after(now, touch_ts + softlockup_thresh)) + if (time_after(now, touch_ts + get_softlockup_thresh())) return now - touch_ts; return 0; @@ -359,7 +370,7 @@ static int watchdog_nmi_enable(int cpu) /* Try to register using hardware perf events */ wd_attr = &wd_hw_attr; - wd_attr->sample_period = hw_nmi_get_sample_period(); + wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback); if (!IS_ERR(event)) { printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n"); @@ -430,9 +441,12 @@ static int watchdog_enable(int cpu) 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); - if (!err) + if (!err) { /* if hardlockup hasn't already set this */ err = PTR_ERR(p); + /* and disable the perf event */ + watchdog_nmi_disable(cpu); + } goto out; } kthread_bind(p, cpu); @@ -498,28 +512,25 @@ static void watchdog_disable_all_cpus(void) /* sysctl functions */ #ifdef CONFIG_SYSCTL /* - * proc handler for /proc/sys/kernel/nmi_watchdog + * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh */ -int proc_dowatchdog_enabled(struct ctl_table *table, int write, - void __user *buffer, size_t *length, loff_t *ppos) +int proc_dowatchdog(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) { - proc_dointvec(table, write, buffer, length, ppos); + int ret; - if (write) { - if (watchdog_enabled) - watchdog_enable_all_cpus(); - else - watchdog_disable_all_cpus(); - } - return 0; -} + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + if (ret || !write) + goto out; -int proc_dowatchdog_thresh(struct ctl_table *table, int write, - void __user *buffer, - size_t *lenp, loff_t *ppos) -{ - return proc_dointvec_minmax(table, write, buffer, lenp, ppos); + if (watchdog_enabled && watchdog_thresh) + watchdog_enable_all_cpus(); + else + watchdog_disable_all_cpus(); + +out: + return ret; } #endif /* CONFIG_SYSCTL */ |