Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'timers_urgent_for_v6.8_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Borislav Petkov:
- Preserve the number of idle calls and sleep entries across CPU
hotplug events in order to be able to compute correct averages
- Limit the duration of the clocksource watchdog checking interval as
too long intervals lead to wrongly marking the TSC as unstable
* tag 'timers_urgent_for_v6.8_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick/sched: Preserve number of idle sleeps across CPU hotplug events
clocksource: Skip watchdog check for large watchdog intervals
+29
-1
+24
-1
kernel/time/clocksource.c
+24
-1
kernel/time/clocksource.c
···
99
99
* Interval: 0.5sec.
100
100
*/
101
101
#define WATCHDOG_INTERVAL (HZ >> 1)
102
+
#define WATCHDOG_INTERVAL_MAX_NS ((2 * WATCHDOG_INTERVAL) * (NSEC_PER_SEC / HZ))
102
103
103
104
/*
104
105
* Threshold: 0.0312s, when doubled: 0.0625s.
···
135
134
static DEFINE_SPINLOCK(watchdog_lock);
136
135
static int watchdog_running;
137
136
static atomic_t watchdog_reset_pending;
137
+
static int64_t watchdog_max_interval;
138
138
139
139
static inline void clocksource_watchdog_lock(unsigned long *flags)
140
140
{
···
401
399
static void clocksource_watchdog(struct timer_list *unused)
402
400
{
403
401
u64 csnow, wdnow, cslast, wdlast, delta;
402
+
int64_t wd_nsec, cs_nsec, interval;
404
403
int next_cpu, reset_pending;
405
-
int64_t wd_nsec, cs_nsec;
406
404
struct clocksource *cs;
407
405
enum wd_read_status read_ret;
408
406
unsigned long extra_wait = 0;
···
471
469
472
470
if (atomic_read(&watchdog_reset_pending))
473
471
continue;
472
+
473
+
/*
474
+
* The processing of timer softirqs can get delayed (usually
475
+
* on account of ksoftirqd not getting to run in a timely
476
+
* manner), which causes the watchdog interval to stretch.
477
+
* Skew detection may fail for longer watchdog intervals
478
+
* on account of fixed margins being used.
479
+
* Some clocksources, e.g. acpi_pm, cannot tolerate
480
+
* watchdog intervals longer than a few seconds.
481
+
*/
482
+
interval = max(cs_nsec, wd_nsec);
483
+
if (unlikely(interval > WATCHDOG_INTERVAL_MAX_NS)) {
484
+
if (system_state > SYSTEM_SCHEDULING &&
485
+
interval > 2 * watchdog_max_interval) {
486
+
watchdog_max_interval = interval;
487
+
pr_warn("Long readout interval, skipping watchdog check: cs_nsec: %lld wd_nsec: %lld\n",
488
+
cs_nsec, wd_nsec);
489
+
}
490
+
watchdog_timer.expires = jiffies;
491
+
continue;
492
+
}
474
493
475
494
/* Check the deviation from the watchdog clocksource. */
476
495
md = cs->uncertainty_margin + watchdog->uncertainty_margin;
+5
kernel/time/tick-sched.c
+5
kernel/time/tick-sched.c
···
1577
1577
{
1578
1578
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
1579
1579
ktime_t idle_sleeptime, iowait_sleeptime;
1580
+
unsigned long idle_calls, idle_sleeps;
1580
1581
1581
1582
# ifdef CONFIG_HIGH_RES_TIMERS
1582
1583
if (ts->sched_timer.base)
···
1586
1585
1587
1586
idle_sleeptime = ts->idle_sleeptime;
1588
1587
iowait_sleeptime = ts->iowait_sleeptime;
1588
+
idle_calls = ts->idle_calls;
1589
+
idle_sleeps = ts->idle_sleeps;
1589
1590
memset(ts, 0, sizeof(*ts));
1590
1591
ts->idle_sleeptime = idle_sleeptime;
1591
1592
ts->iowait_sleeptime = iowait_sleeptime;
1593
+
ts->idle_calls = idle_calls;
1594
+
ts->idle_sleeps = idle_sleeps;
1592
1595
}
1593
1596
#endif
1594
1597