diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2024-01-28 10:33:14 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2024-01-28 10:33:14 -0800 |
commit | 90db544ebaf4325044402cdfecf1cf9247ca3ae6 (patch) | |
tree | 30b5ca4b7bddbbd3e018371689829666c9c72503 /kernel | |
parent | 9d451912dbef72b4b4dcaa99229f98b309338b39 (diff) | |
parent | 9a574ea9069be30b835a3da772c039993c43369b (diff) |
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
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/time/clocksource.c | 25 | ||||
-rw-r--r-- | kernel/time/tick-sched.c | 5 |
2 files changed, 29 insertions, 1 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index c108ed8a9804..3052b1f1168e 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -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) { diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index d2501673028d..01fb50c1b17e 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -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 |