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While the !highres/!dyntick code assigns the duty of the do_timer() call to
one specific CPU, this was dropped in the highres/dyntick part during
development.
Steven Rostedt discovered the xtime lock contention on highres/dyntick due
to several CPUs trying to update jiffies.
Add the single CPU assignement back. In the dyntick case this needs to be
handled carefully, as the CPU which has the do_timer() duty must drop the
assignement and let it be grabbed by another CPU, which is active.
Otherwise the do_timer() calls would not happen during the long sleep.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Mark Lord <mlord@pobox.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I finally found a dual core box, which survives suspend/resume without
crashing in the middle of nowhere. Sigh, I never figured out from the
code and the bug reports what's going on.
The observed hangs are caused by a stale state transition of the clock
event devices, which keeps the RCU synchronization away from completion,
when the non boot CPU is brought back up.
The suspend/resume in oneshot mode needs the similar care as the
periodic mode during suspend to RAM. My assumption that the state
transitions during the different shutdown/bringups of s2disk would go
through the periodic boot phase and then switch over to highres resp.
nohz mode were simply wrong.
Add the appropriate suspend / resume handling for the non periodic
modes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The programming of periodic tick devices needs to be saved/restored
across suspend/resume - otherwise we might end up with a system coming
up that relies on getting a PIT (or HPET) interrupt, while those devices
default to 'no interrupts' after powerup. (To confuse things it worked
to a certain degree on some systems because the lapic gets initialized
as a side-effect of SMP bootup.)
This suspend / resume thing was dropped unintentionally during the
last-minute -mm code reshuffling.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When clockevents_program_event() is given an expire time in the
past, it does not update dev->next_event, so this looping code
would loop forever once the first in-the-past expiration time
was used.
Keep advancing "next" locally to fix this bug.
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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add /proc/timer_list, which prints all currently pending (high-res) timers,
all clock-event sources and their parameters in a human-readable form.
Sample output:
Timer List Version: v0.1
HRTIMER_MAX_CLOCK_BASES: 2
now at 4246046273872 nsecs
cpu: 0
clock 0:
.index: 0
.resolution: 1 nsecs
.get_time: ktime_get_real
.offset: 1273998312645738432 nsecs
active timers:
clock 1:
.index: 1
.resolution: 1 nsecs
.get_time: ktime_get
.offset: 0 nsecs
active timers:
#0: <f5a90ec8>, hrtimer_sched_tick, hrtimer_stop_sched_tick, swapper/0
# expires at 4246432689566 nsecs [in 386415694 nsecs]
#1: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, pcscd/2050
# expires at 4247018194689 nsecs [in 971920817 nsecs]
#2: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, irqbalance/1909
# expires at 4247351358392 nsecs [in 1305084520 nsecs]
#3: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, crond/2157
# expires at 4249097614968 nsecs [in 3051341096 nsecs]
#4: <f5a90ec8>, it_real_fn, do_setitimer, syslogd/1888
# expires at 4251329900926 nsecs [in 5283627054 nsecs]
.expires_next : 4246432689566 nsecs
.hres_active : 1
.check_clocks : 0
.nr_events : 31306
.idle_tick : 4246020791890 nsecs
.tick_stopped : 1
.idle_jiffies : 986504
.idle_calls : 40700
.idle_sleeps : 36014
.idle_entrytime : 4246019418883 nsecs
.idle_sleeptime : 4178181972709 nsecs
cpu: 1
clock 0:
.index: 0
.resolution: 1 nsecs
.get_time: ktime_get_real
.offset: 1273998312645738432 nsecs
active timers:
clock 1:
.index: 1
.resolution: 1 nsecs
.get_time: ktime_get
.offset: 0 nsecs
active timers:
#0: <f5a90ec8>, hrtimer_sched_tick, hrtimer_restart_sched_tick, swapper/0
# expires at 4246050084568 nsecs [in 3810696 nsecs]
#1: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, atd/2227
# expires at 4261010635003 nsecs [in 14964361131 nsecs]
#2: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, smartd/2332
# expires at 5469485798970 nsecs [in 1223439525098 nsecs]
.expires_next : 4246050084568 nsecs
.hres_active : 1
.check_clocks : 0
.nr_events : 24043
.idle_tick : 4246046084568 nsecs
.tick_stopped : 0
.idle_jiffies : 986510
.idle_calls : 26360
.idle_sleeps : 22551
.idle_entrytime : 4246043874339 nsecs
.idle_sleeptime : 4170763761184 nsecs
tick_broadcast_mask: 00000003
event_broadcast_mask: 00000001
CPU#0's local event device:
Clock Event Device: lapic
capabilities: 0000000e
max_delta_ns: 807385544
min_delta_ns: 1443
mult: 44624025
shift: 32
set_next_event: lapic_next_event
set_mode: lapic_timer_setup
event_handler: hrtimer_interrupt
.installed: 1
.expires: 4246432689566 nsecs
CPU#1's local event device:
Clock Event Device: lapic
capabilities: 0000000e
max_delta_ns: 807385544
min_delta_ns: 1443
mult: 44624025
shift: 32
set_next_event: lapic_next_event
set_mode: lapic_timer_setup
event_handler: hrtimer_interrupt
.installed: 1
.expires: 4246050084568 nsecs
Clock Event Device: hpet
capabilities: 00000007
max_delta_ns: 2147483647
min_delta_ns: 3352
mult: 61496110
shift: 32
set_next_event: hpet_next_event
set_mode: hpet_set_mode
event_handler: handle_nextevt_broadcast
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With Ingo Molnar <mingo@elte.hu>
Add functions to provide dynamic ticks and high resolution timers. The code
which keeps track of jiffies and handles the long idle periods is shared
between tick based and high resolution timer based dynticks. The dyntick
functionality can be disabled on the kernel commandline. Provide also the
infrastructure to support high resolution timers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With Ingo Molnar <mingo@elte.hu>
Add broadcast functionality, so per cpu clock event devices can be registered
as dummy devices or switched from/to broadcast on demand. The broadcast
function distributes the events via the broadcast function of the clock event
device. This is primarily designed to replace the switch apic timer to / from
IPI in power states, where the apic stops.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With Ingo Molnar <mingo@elte.hu>
The tick-management code is the first user of the clockevents layer. It takes
clock event devices from the clock events core and uses them to provide the
periodic tick.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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