diff options
| author | Frederic Weisbecker <frederic@kernel.org> | 2022-02-02 01:01:07 +0100 |
|---|---|---|
| committer | Frederic Weisbecker <frederic@kernel.org> | 2022-03-07 23:01:19 +0100 |
| commit | a1ff03cd6fb9c501fff63a4a2bface9adcfa81cd (patch) | |
| tree | 5a5e4af9948395d52664857409bb6d4c4811efe8 /kernel/time/tick-sched.c | |
| parent | 58dedf0a4782ce42b4d31f1f62e5ad80a1b73d72 (diff) | |
| download | linux-a1ff03cd6fb9c501fff63a4a2bface9adcfa81cd.tar.gz | |
tick: Detect and fix jiffies update stall
On some rare cases, the timekeeper CPU may be delaying its jiffies
update duty for a while. Known causes include:
* The timekeeper is waiting on stop_machine in a MULTI_STOP_DISABLE_IRQ
or MULTI_STOP_RUN state. Disabled interrupts prevent from timekeeping
updates while waiting for the target CPU to complete its
stop_machine() callback.
* The timekeeper vcpu has VMEXIT'ed for a long while due to some overload
on the host.
Detect and fix these situations with emergency timekeeping catchups.
Original-patch-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time/tick-sched.c')
| -rw-r--r-- | kernel/time/tick-sched.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 17a283ce2b20fb..c89f50a7e6903e 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -169,6 +169,8 @@ static ktime_t tick_init_jiffy_update(void) return period; } +#define MAX_STALLED_JIFFIES 5 + static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now) { int cpu = smp_processor_id(); @@ -196,6 +198,21 @@ static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now) if (tick_do_timer_cpu == cpu) tick_do_update_jiffies64(now); + /* + * If jiffies update stalled for too long (timekeeper in stop_machine() + * or VMEXIT'ed for several msecs), force an update. + */ + if (ts->last_tick_jiffies != jiffies) { + ts->stalled_jiffies = 0; + ts->last_tick_jiffies = READ_ONCE(jiffies); + } else { + if (++ts->stalled_jiffies == MAX_STALLED_JIFFIES) { + tick_do_update_jiffies64(now); + ts->stalled_jiffies = 0; + ts->last_tick_jiffies = READ_ONCE(jiffies); + } + } + if (ts->inidle) ts->got_idle_tick = 1; } |