diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/softlockup.c | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/kernel/softlockup.c b/kernel/softlockup.c index 81d43caa2012..5ea631742dbc 100644 --- a/kernel/softlockup.c +++ b/kernel/softlockup.c @@ -34,9 +34,19 @@ static struct notifier_block panic_block = { .notifier_call = softlock_panic, }; +/* + * 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(void) +{ + return sched_clock() >> 30; /* 2^30 ~= 10^9 */ +} + void touch_softlockup_watchdog(void) { - __raw_get_cpu_var(touch_timestamp) = jiffies; + __raw_get_cpu_var(touch_timestamp) = get_timestamp(); } EXPORT_SYMBOL(touch_softlockup_watchdog); @@ -48,9 +58,17 @@ void softlockup_tick(void) { int this_cpu = smp_processor_id(); unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu); + unsigned long print_timestamp; + unsigned long now; - /* prevent double reports: */ - if (per_cpu(print_timestamp, this_cpu) == touch_timestamp || + /* watchdog task hasn't updated timestamp yet */ + if (touch_timestamp == 0) + return; + + print_timestamp = per_cpu(print_timestamp, this_cpu); + + /* report at most once a second */ + if (print_timestamp < (touch_timestamp + 1) || did_panic || !per_cpu(watchdog_task, this_cpu)) return; @@ -61,12 +79,14 @@ void softlockup_tick(void) return; } + now = get_timestamp(); + /* Wake up the high-prio watchdog task every second: */ - if (time_after(jiffies, touch_timestamp + HZ)) + if (now > (touch_timestamp + 1)) wake_up_process(per_cpu(watchdog_task, this_cpu)); /* Warn about unreasonable 10+ seconds delays: */ - if (time_after(jiffies, touch_timestamp + 10*HZ)) { + if (now > (touch_timestamp + 10)) { per_cpu(print_timestamp, this_cpu) = touch_timestamp; spin_lock(&print_lock); @@ -87,6 +107,9 @@ static int watchdog(void * __bind_cpu) sched_setscheduler(current, SCHED_FIFO, ¶m); current->flags |= PF_NOFREEZE; + /* initialize timestamp */ + touch_softlockup_watchdog(); + /* * Run briefly once per second to reset the softlockup timestamp. * If this gets delayed for more than 10 seconds then the @@ -118,7 +141,7 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) printk("watchdog for %i failed\n", hotcpu); return NOTIFY_BAD; } - per_cpu(touch_timestamp, hotcpu) = jiffies; + per_cpu(touch_timestamp, hotcpu) = 0; per_cpu(watchdog_task, hotcpu) = p; kthread_bind(p, hotcpu); break; |