Commit 90db544e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents 9d451912 9a574ea9

kernel/time/clocksource.c

+24 −1
Original line number Diff line number Diff line
@@ -99,6 +99,7 @@ static u64 suspend_start; 
 * Interval: 0.5sec.

 */

#define WATCHDOG_INTERVAL (HZ >> 1)

#define WATCHDOG_INTERVAL_MAX_NS ((2 * WATCHDOG_INTERVAL) * (NSEC_PER_SEC / HZ))



/*

 * Threshold: 0.0312s, when doubled: 0.0625s.
@@ -134,6 +135,7 @@ static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); 
static DEFINE_SPINLOCK(watchdog_lock);

static int watchdog_running;

static atomic_t watchdog_reset_pending;

static int64_t watchdog_max_interval;



static inline void clocksource_watchdog_lock(unsigned long *flags)

{
@@ -399,8 +401,8 @@ static inline void clocksource_reset_watchdog(void) 
static void clocksource_watchdog(struct timer_list *unused)

{

	u64 csnow, wdnow, cslast, wdlast, delta;

	int64_t wd_nsec, cs_nsec, interval;

	int next_cpu, reset_pending;

	int64_t wd_nsec, cs_nsec;

	struct clocksource *cs;

	enum wd_read_status read_ret;

	unsigned long extra_wait = 0;
@@ -470,6 +472,27 @@ static void clocksource_watchdog(struct timer_list *unused) 
		if (atomic_read(&watchdog_reset_pending))

			continue;



		/*

		 * The processing of timer softirqs can get delayed (usually

		 * on account of ksoftirqd not getting to run in a timely

		 * manner), which causes the watchdog interval to stretch.

		 * Skew detection may fail for longer watchdog intervals

		 * on account of fixed margins being used.

		 * Some clocksources, e.g. acpi_pm, cannot tolerate

		 * watchdog intervals longer than a few seconds.

		 */

		interval = max(cs_nsec, wd_nsec);

		if (unlikely(interval > WATCHDOG_INTERVAL_MAX_NS)) {

			if (system_state > SYSTEM_SCHEDULING &&

			    interval > 2 * watchdog_max_interval) {

				watchdog_max_interval = interval;

				pr_warn("Long readout interval, skipping watchdog check: cs_nsec: %lld wd_nsec: %lld\n",

					cs_nsec, wd_nsec);

			}

			watchdog_timer.expires = jiffies;

			continue;

		}



		/* Check the deviation from the watchdog clocksource. */

		md = cs->uncertainty_margin + watchdog->uncertainty_margin;

		if (abs(cs_nsec - wd_nsec) > md) {

kernel/time/tick-sched.c

+5 −0
Original line number Diff line number Diff line
@@ -1577,6 +1577,7 @@ void tick_cancel_sched_timer(int cpu) 
{

	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);

	ktime_t idle_sleeptime, iowait_sleeptime;

	unsigned long idle_calls, idle_sleeps;



# ifdef CONFIG_HIGH_RES_TIMERS

	if (ts->sched_timer.base)
@@ -1585,9 +1586,13 @@ void tick_cancel_sched_timer(int cpu) 


	idle_sleeptime = ts->idle_sleeptime;

	iowait_sleeptime = ts->iowait_sleeptime;

	idle_calls = ts->idle_calls;

	idle_sleeps = ts->idle_sleeps;

	memset(ts, 0, sizeof(*ts));

	ts->idle_sleeptime = idle_sleeptime;

	ts->iowait_sleeptime = iowait_sleeptime;

	ts->idle_calls = idle_calls;

	ts->idle_sleeps = idle_sleeps;

}

#endif