From 0695bd99c0d22bef4d9d4c72cf537b722ba98531 Mon Sep 17 00:00:00 2001 From: Nicolai Stange Date: Mon, 6 Feb 2017 22:12:04 +0100 Subject: clockevents: Make clockevents_config() static A clockevent device's rate should be configured before or at registration and changed afterwards through clockevents_update_freq() only. For the configuration at registration, we already have clockevents_config_and_register(). Right now, there are no clockevents_config() users outside of the clockevents core. To mitigiate the risk of drivers errorneously reconfiguring their rates through clockevents_config() *after* device registration, make clockevents_config() static. Signed-off-by: Nicolai Stange Signed-off-by: John Stultz --- kernel/time/clockevents.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/time') diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 97ac0951f164..4237e0744e26 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -468,7 +468,7 @@ void clockevents_register_device(struct clock_event_device *dev) } EXPORT_SYMBOL_GPL(clockevents_register_device); -void clockevents_config(struct clock_event_device *dev, u32 freq) +static void clockevents_config(struct clock_event_device *dev, u32 freq) { u64 sec; -- cgit v1.2.3 From 1b8955bc5ac575009835e371ae55e7f3af2197a9 Mon Sep 17 00:00:00 2001 From: David Engraf Date: Fri, 17 Feb 2017 08:51:03 +0100 Subject: timers, sched_clock: Update timeout for clock wrap The scheduler clock framework may not use the correct timeout for the clock wrap. This happens when a new clock driver calls sched_clock_register() after the kernel called sched_clock_postinit(). In this case the clock wrap timeout is too long thus sched_clock_poll() is called too late and the clock already wrapped. On my ARM system the scheduler was no longer scheduling any other task than the idle task because the sched_clock() wrapped. Signed-off-by: David Engraf Signed-off-by: John Stultz --- kernel/time/sched_clock.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel/time') diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index ea6b610c4c57..2d8f05aad442 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -206,6 +206,11 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate) update_clock_read_data(&rd); + if (sched_clock_timer.function != NULL) { + /* update timeout for clock wrap */ + hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + } + r = rate; if (r >= 4000000) { r /= 1000000; -- cgit v1.2.3 From 0107042768658fea9f5f5a9c00b1c90f5dab6a06 Mon Sep 17 00:00:00 2001 From: Tom Hromatka Date: Wed, 4 Jan 2017 15:28:04 -0700 Subject: sysrq: Reset the watchdog timers while displaying high-resolution timers On systems with a large number of CPUs, running sysrq- can cause watchdog timeouts. There are two slow sections of code in the sysrq- path in timer_list.c. 1. print_active_timers() - This function is called by print_cpu() and contains a slow goto loop. On a machine with hundreds of CPUs, this loop took approximately 100ms for the first CPU in a NUMA node. (Subsequent CPUs in the same node ran much quicker.) The total time to print all of the CPUs is ultimately long enough to trigger the soft lockup watchdog. 2. print_tickdevice() - This function outputs a large amount of textual information. This function also took approximately 100ms per CPU. Since sysrq- is not a performance critical path, there should be no harm in touching the nmi watchdog in both slow sections above. Touching it in just one location was insufficient on systems with hundreds of CPUs as occasional timeouts were still observed during testing. This issue was observed on an Oracle T7 machine with 128 CPUs, but I anticipate it may affect other systems with similarly large numbers of CPUs. Signed-off-by: Tom Hromatka Reviewed-by: Rob Gardner Signed-off-by: John Stultz --- kernel/time/timer_list.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel/time') diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c index ff8d5c13d04b..0e7f5428a148 100644 --- a/kernel/time/timer_list.c +++ b/kernel/time/timer_list.c @@ -16,6 +16,7 @@ #include #include #include +#include #include @@ -86,6 +87,9 @@ print_active_timers(struct seq_file *m, struct hrtimer_clock_base *base, next_one: i = 0; + + touch_nmi_watchdog(); + raw_spin_lock_irqsave(&base->cpu_base->lock, flags); curr = timerqueue_getnext(&base->active); @@ -197,6 +201,8 @@ print_tickdevice(struct seq_file *m, struct tick_device *td, int cpu) { struct clock_event_device *dev = td->evtdev; + touch_nmi_watchdog(); + SEQ_printf(m, "Tick Device: mode: %d\n", td->mode); if (cpu < 0) SEQ_printf(m, "Broadcast device\n"); -- cgit v1.2.3