watchdog: store the watchdog sample period as a variable
Currently getting the sample period is always thru a complex
calculation: get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5).
We can store the sample period as a variable, and set it as __read_mostly
type.
Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Cc: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index c8c21be..997c6a1 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -31,6 +31,7 @@
int watchdog_enabled = 1;
int __read_mostly watchdog_thresh = 10;
static int __read_mostly watchdog_disabled;
+static u64 __read_mostly sample_period;
static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
@@ -116,7 +117,7 @@
return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
}
-static u64 get_sample_period(void)
+static void set_sample_period(void)
{
/*
* convert watchdog_thresh from seconds to ns
@@ -125,7 +126,7 @@
* and hard thresholds) to increment before the
* hardlockup detector generates a warning
*/
- return get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
+ sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
}
/* Commands for resetting the watchdog */
@@ -275,7 +276,7 @@
wake_up_process(__this_cpu_read(softlockup_watchdog));
/* .. and repeat */
- hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
+ hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
if (touch_ts == 0) {
if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
@@ -356,7 +357,7 @@
hrtimer->function = watchdog_timer_fn;
/* done here because hrtimer_start can only pin to smp_processor_id() */
- hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
+ hrtimer_start(hrtimer, ns_to_ktime(sample_period),
HRTIMER_MODE_REL_PINNED);
/* initialize timestamp */
@@ -386,7 +387,7 @@
/*
* The watchdog thread function - touches the timestamp.
*
- * It only runs once every get_sample_period() seconds (4 seconds by
+ * It only runs once every sample_period seconds (4 seconds by
* default) to reset the softlockup timestamp. If this gets delayed
* for more than 2*watchdog_thresh seconds then the debug-printout
* triggers in watchdog_timer_fn().
@@ -519,6 +520,7 @@
if (ret || !write)
return ret;
+ set_sample_period();
if (watchdog_enabled && watchdog_thresh)
watchdog_enable_all_cpus();
else
@@ -540,6 +542,7 @@
void __init lockup_detector_init(void)
{
+ set_sample_period();
if (smpboot_register_percpu_thread(&watchdog_threads)) {
pr_err("Failed to create watchdog threads, disabled\n");
watchdog_disabled = -ENODEV;