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The FIFO guarantee is only there if two timers are queued into the
same bucket at the same jiffie on the same cpu:
- The slack value depends on the delta between expiry and enqueue
time, so the resulting expiry time can be different for timers
which are queued in different jiffies.
- Timers which are queued into the secondary array end up after a
later queued timer which was queued into the primary array due to
cascading.
- Timers can end up on different cpus due to the NOHZ target moving
around. Obviously there is no guarantee of expiry ordering between
cpus.
So anything which relies on FIFO behaviour of the timer wheel is
broken already.
This is a preparatory patch for converting the timer wheel to hlist
which reduces the memory foot print of the wheel by 50%.
It's a seperate patch so any (unlikely to happen) regression caused by
this can be identified clearly.
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Viresh Kumar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Paul McKenney <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Joonwoo Park <[email protected]>
Cc: Wenbo Wang <[email protected]>
Cc: George Spelvin <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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catchup_timer_jiffies() has been applied blindly to several functions
without looking for possible better ways to do it.
1) internal_add_timer()
Move the update to base->all_timers before we actually insert the
timer into the wheel.
2) detach_if_pending()
Again the update to base->all_timers allows us to explicitely do
the timer_jiffies update in place, if this was the last timer which
got removed.
3) __run_timers()
We only check on entry, which is silly, because base->timer_jiffies
can be behind - especially on NOHZ kernels - and if there is a
single deferrable timer somewhere between base->timer_jiffies and
jiffies we expire it and then loop until base->timer_jiffies ==
jiffies.
Move it into the loop.
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Paul McKenney <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Joonwoo Park <[email protected]>
Cc: Wenbo Wang <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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* pm-sleep:
PM / sleep: trace_device_pm_callback coverage in dpm_prepare/complete
PM / wakeup: add a dummy wakeup_source to record statistics
PM / sleep: Make suspend-to-idle-specific code depend on CONFIG_SUSPEND
PM / sleep: Return -EBUSY from suspend_enter() on wakeup detection
PM / tick: Add tracepoints for suspend-to-idle diagnostics
PM / sleep: Fix symbol name in a comment in kernel/power/main.c
leds / PM: fix hibernation on arm when gpio-led used with CPU led trigger
ARM: omap-device: use SET_NOIRQ_SYSTEM_SLEEP_PM_OPS
bus: omap_l3_noc: add missed callbacks for suspend-to-disk
PM / sleep: Add macro to define common noirq system PM callbacks
PM / sleep: Refine diagnostic messages in enter_state()
PM / wakeup: validate wakeup source before activating it.
* pm-runtime:
PM / Runtime: Update last_busy in rpm_resume
PM / runtime: add note about re-calling in during device probe()
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Currently an hrtimer callback function cannot free its own timer
because __run_hrtimer() still needs to clear HRTIMER_STATE_CALLBACK
after it. Freeing the timer would result in a clear use-after-free.
Solve this by using a scheme similar to regular timers; track the
current running timer in hrtimer_clock_base::running.
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Al Viro <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul McKenney <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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A queued hrtimer that gets restarted (hrtimer_start*() while
hrtimer_is_queued()) will briefly appear as unqueued/inactive, even
though the timer has always been active, we just moved it.
Close this hole by preserving timer->state in
hrtimer_start_range_ns()'s remove_hrtimer() call.
Reported-by: Oleg Nesterov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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I do not understand HRTIMER_STATE_MIGRATE. Unless I am totally
confused it looks buggy and simply unneeded.
migrate_hrtimer_list() sets it to keep hrtimer_active() == T, but this
is not enough: this can fool, say, hrtimer_is_queued() in
dequeue_signal().
Can't migrate_hrtimer_list() simply use HRTIMER_STATE_ENQUEUED?
This fixes the race and we can kill STATE_MIGRATE.
Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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The fix in d151832650ed9 (time: Move clock_was_set_seq update
before updating shadow-timekeeper) was unfortunately incomplete.
The main gist of that change was to do the shadow-copy update
last, so that any state changes were properly duplicated, and
we wouldn't accidentally have stale data in the shadow.
Unfortunately in the main update_wall_time() logic, we update
use the shadow-timekeeper to calculate the next update values,
then while holding the lock, copy the shadow-timekeeper over,
then call timekeeping_update() to do some additional
bookkeeping, (skipping the shadow mirror). The bug with this is
the additional bookkeeping isn't all read-only, and some
changes timkeeper state. Thus we might then overwrite this state
change on the next update.
To avoid this problem, do the timekeeping_update() on the
shadow-timekeeper prior to copying the full state over to
the real-timekeeper.
This avoids problems with both the clock_was_set_seq and
next_leap_ktime being overwritten and possibly the
fast-timekeepers as well.
Many thanks to Prarit for his rigorous testing, which discovered
this problem, along with Prarit and Daniel's work validating this
fix.
Reported-by: Prarit Bhargava <[email protected]>
Tested-by: Prarit Bhargava <[email protected]>
Tested-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jiri Bohac <[email protected]>
Cc: Ingo Molnar <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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CLOCK_EVT_MODE_* macros are present for backward compatibility (as most
of the drivers are still using old ->set_mode() interface).
These macro's shouldn't be used anymore in code, that is common to both
driver interfaces, i.e. ->set_mode() and ->set_state_*().
Drivers implementing ->set_state_*() interface, which have their
clkevt->mode set to 0 (clkevt device structures are normally globally
defined), will not participate in suspend/resume as they will always be
marked as UNUSED.
Fix this by checking state of the clockevent device instead of mode,
which is updated for both the interfaces.
Fixes: ac34ad27fc16 ("clockevents: Do not suspend/resume if unused")
Signed-off-by: Viresh Kumar <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/a1964eef6e8a47d02b1ff9083c6c91f73f0ff643.1434537215.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <[email protected]>
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Since the leapsecond is applied at tick-time, this means there is a
small window of time at the start of a leap-second where we cross into
the next second before applying the leap.
This patch modified adjtimex so that the leap-second is applied on the
second edge. Providing more correct leapsecond behavior.
This does make it so that adjtimex()'s returned time values can be
inconsistent with time values read from gettimeofday() or
clock_gettime(CLOCK_REALTIME,...) for a brief period of one tick at
the leapsecond. However, those other interfaces do not provide the
TIME_OOP time_state return that adjtimex() provides, which allows the
leapsecond to be properly represented. They instead only see a time
discontinuity, and cannot tell the first 23:59:59 from the repeated
23:59:59 leap second.
This seems like a reasonable tradeoff given clock_gettime() /
gettimeofday() cannot properly represent a leapsecond, and users
likely care more about performance, while folks who are using
adjtimex() more likely care about leap-second correctness.
Signed-off-by: John Stultz <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Daniel Bristot de Oliveira <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jiri Bohac <[email protected]>
Cc: Ingo Molnar <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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Currently, leapsecond adjustments are done at tick time. As a result,
the leapsecond was applied at the first timer tick *after* the
leapsecond (~1-10ms late depending on HZ), rather then exactly on the
second edge.
This was in part historical from back when we were always tick based,
but correcting this since has been avoided since it adds extra
conditional checks in the gettime fastpath, which has performance
overhead.
However, it was recently pointed out that ABS_TIME CLOCK_REALTIME
timers set for right after the leapsecond could fire a second early,
since some timers may be expired before we trigger the timekeeping
timer, which then applies the leapsecond.
This isn't quite as bad as it sounds, since behaviorally it is similar
to what is possible w/ ntpd made leapsecond adjustments done w/o using
the kernel discipline. Where due to latencies, timers may fire just
prior to the settimeofday call. (Also, one should note that all
applications using CLOCK_REALTIME timers should always be careful,
since they are prone to quirks from settimeofday() disturbances.)
However, the purpose of having the kernel do the leap adjustment is to
avoid such latencies, so I think this is worth fixing.
So in order to properly keep those timers from firing a second early,
this patch modifies the ntp and timekeeping logic so that we keep
enough state so that the update_base_offsets_now accessor, which
provides the hrtimer core the current time, can check and apply the
leapsecond adjustment on the second edge. This prevents the hrtimer
core from expiring timers too early.
This patch does not modify any other time read path, so no additional
overhead is incurred. However, this also means that the leap-second
continues to be applied at tick time for all other read-paths.
Apologies to Richard Cochran, who pushed for similar changes years
ago, which I resisted due to the concerns about the performance
overhead.
While I suspect this isn't extremely critical, folks who care about
strict leap-second correctness will likely want to watch
this. Potentially a -stable candidate eventually.
Originally-suggested-by: Richard Cochran <[email protected]>
Reported-by: Daniel Bristot de Oliveira <[email protected]>
Reported-by: Prarit Bhargava <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jiri Bohac <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Ingo Molnar <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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Currently the leapsecond logic uses what looks like magic values.
Improve this by defining SECS_PER_DAY and using that macro
to make the logic more clear.
Signed-off-by: John Stultz <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Daniel Bristot de Oliveira <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jiri Bohac <[email protected]>
Cc: Ingo Molnar <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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It was reported that 868a3e915f7f5eba (hrtimer: Make offset
update smarter) was causing timer problems after suspend/resume.
The problem with that change is the modification to
clock_was_set_seq in timekeeping_update is done prior to
mirroring the time state to the shadow-timekeeper. Thus the
next time we do update_wall_time() the updated sequence is
overwritten by whats in the shadow copy.
This patch moves the shadow-timekeeper mirroring to the end
of the function, after all updates have been made, so all data
is kept in sync.
(This patch also affects the update_fast_timekeeper calls which
were also problematically done prior to the mirroring).
Reported-and-tested-by: Jeremiah Mahler <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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clocksource messages aren't prefixed in dmesg so it's a bit unclear
what subsystem emits the messages.
Use pr_fmt and pr_<level> to auto-prefix the messages appropriately.
Miscellanea:
o Remove "Warning" from KERN_WARNING level messages
o Align "timekeeping watchdog: " messages
o Coalesce formats
o Align multiline arguments
Signed-off-by: Joe Perches <[email protected]>
Cc: John Stultz <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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Refactor the usecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability. This is analogous to the msecs_to_jiffies()
cleanup in commit ca42aaf0c861 ("time: Refactor msecs_to_jiffies")
Signed-off-by: Nicholas Mc Guire <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Andrew Hunter <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Michal Marek <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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The only sensible way to make abuse of core internal fields obvious
and easy to grep for.
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
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Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
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We want to rename dev->state, so provide proper get and set
functions. Rename clockevents_set_state() to
clockevents_switch_state() to avoid confusion.
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
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Use accessor functions to check the state of clockevent devices in
core code.
Signed-off-by: Viresh Kumar <[email protected]>
Cc: [email protected]
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/fa2b9869fd17f210eaa156ec2b594efd0230b6c7.1432192527.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <[email protected]>
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Conflicts:
arch/sparc/include/asm/topology_64.h
Signed-off-by: Ingo Molnar <[email protected]>
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Because with latches there is a strict data dependency on the seq load
we can avoid the rmb in favour of a read_barrier_depends.
Suggested-by: Ingo Molnar <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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Improve the documentation of the latch technique as used in the
current timekeeping code, such that it can be readily employed
elsewhere.
Borrow from the comments in timekeeping and replace those with a
reference to this more generic comment.
Cc: Andrea Arcangeli <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Reviewed-by: Mathieu Desnoyers <[email protected]>
Acked-by: Michel Lespinasse <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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There is no point in calling suspend/resume for unused clockevents as
they are already stopped and disabled.
This is really important for AT91 as the hardware is a trainwreck and
takes ages to synchronize.
Reported-by: Sylvain Rochet <[email protected]>
Signed-off-by: Alexandre Belloni <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Nicolas Ferre <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/1421399151-26800-1-git-send-email-alexandre.belloni@free-electrons.com
Signed-off-by: Thomas Gleixner <[email protected]>
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Now that we have a read_boot_clock64() function available on every
architecture, and converted all the users to it, it's time to remove
the (now unused) read_boot_clock() completely from the kernel.
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Xunlei Pang <[email protected]>
[jstultz: Minor commit message tweak suggested by Ingo]
Signed-off-by: John Stultz <[email protected]>
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The timer_start event now shows whether the timer is
deferrable in case of a low-res timer. The debug_activate
function now includes a deferrable flag while calling
the trace_timer_start event.
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Acked-by: Steven Rostedt <[email protected]>
Signed-off-by: Badhri Jagan Sridharan <[email protected]>
[jstultz: Fixed minor whitespace and grammer tweaks
pointed out by Ingo]
Signed-off-by: John Stultz <[email protected]>
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Ingo suggested that the timekeeping debugging variables
recently added should not be global, and should be tied
to the timekeeper's read_base.
Thus this patch implements that suggestion.
This version is different from the earlier versions
as it keeps the variables in the timekeeper structure
rather then in the tkr.
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Richard Cochran <[email protected]>
Signed-off-by: John Stultz <[email protected]>
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This patch series introduces a new function
u32 ktime_get_resolution_ns(void)
which allows to clean up some driver code.
In particular the IIO subsystem has a function to provide timestamps for
events but no means to get their resolution. So currently the dht11 driver
tries to guess the resolution in a rather messy and convoluted way. We
can do much better with the new code.
This API is not designed to be exposed to user space.
This has been tested on i386, sunxi and mxs.
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Harald Geyer <[email protected]>
[jstultz: Tweaked to make it build after upstream changes]
Signed-off-by: John Stultz <[email protected]>
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Invalid values may overflow later, leading to undefined behaviour when
multiplied by 60 to get the amount of seconds.
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: John Stultz <[email protected]>
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To avoid getting spurious interrupts on a tickless CPU, clockevent
device can now be stopped by switching to ONESHOT_STOPPED state.
The natural place for handling this transition is tick_program_event().
On 'expires == KTIME_MAX', we skip programming the event and so we need
to fix such call sites as well, to always call tick_program_event()
irrespective of the expires value.
Once the clockevent device is required again, check if it was earlier
put into ONESHOT_STOPPED state. If yes, switch its state to ONESHOT
before programming its event.
To make sure we haven't missed any corner case, add a WARN() for the
case where we try to reprogram clockevent device while we aren't
configured in ONESHOT_STOPPED state.
Signed-off-by: Viresh Kumar <[email protected]>
Cc: [email protected]
Cc: Frederic Weisbecker <[email protected]>
Cc: Kevin Hilman <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/5146b07be7f0bc497e0ebae036590ec2fa73e540.1428031396.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <[email protected]>
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When no timers/hrtimers are pending, the expiry time is set to a
special value: 'KTIME_MAX'. This normally happens with
NO_HZ_{IDLE|FULL} in both LOWRES/HIGHRES modes.
When 'expiry == KTIME_MAX', we either cancel the 'tick-sched' hrtimer
(NOHZ_MODE_HIGHRES) or skip reprogramming clockevent device
(NOHZ_MODE_LOWRES). But, the clockevent device is already
reprogrammed from the tick-handler for next tick.
As the clock event device is programmed in ONESHOT mode it will at
least fire one more time (unnecessarily). Timers on few
implementations (like arm_arch_timer, etc.) only support PERIODIC mode
and their drivers emulate ONESHOT over that. Which means that on these
platforms we will get spurious interrupts periodically (at last
programmed interval rate, normally tick rate).
In order to avoid spurious interrupts, the clockevent device should be
stopped or its interrupts should be masked.
A simple (yet hacky) solution to get this fixed could be: update
hrtimer_force_reprogram() to always reprogram clockevent device and
update clockevent drivers to STOP generating events (or delay it to
max time) when 'expires' is set to KTIME_MAX. But the drawback here is
that every clockevent driver has to be hacked for this particular case
and its very easy for new ones to miss this.
However, Thomas suggested to add an optional state ONESHOT_STOPPED to
solve this problem: lkml.org/lkml/2014/5/9/508.
This patch adds support for ONESHOT_STOPPED state in clockevents
core. It will only be available to drivers that implement the
state-specific callbacks instead of the legacy ->set_mode() callback.
Signed-off-by: Viresh Kumar <[email protected]>
Reviewed-by: Preeti U. Murthy <[email protected]>
Cc: [email protected]
Cc: Frederic Weisbecker <[email protected]>
Cc: Kevin Hilman <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/b8b383a03ac07b13312c16850b5106b82e4245b5.1428031396.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <[email protected]>
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Make sure the upstream fixes are applied before adding further
modifications.
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Refactor the msecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability.
[ tglx: Verified that there is no binary code change ]
Signed-off-by: Nicholas Mc Guire <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Andrew Hunter <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Michal Marek <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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kernel/time/timeconst.h is moved to include/generated/ and generated
by the top level Kbuild. This allows using timeconst.h in an earlier
build stage.
Signed-off-by: Nicholas Mc Guire <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Andrew Hunter <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Michal Marek <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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Signed-off-by: Ingo Molnar <[email protected]>
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Since idle_should_freeze() is defined to always return 'false'
for CONFIG_SUSPEND unset, all of the code depending on it in
cpuidle_idle_call() is not necessary in that case.
Make that code depend on CONFIG_SUSPEND too to avoid building it
when it is not going to be used.
Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
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Add suspend/resume tracepoints to tick_freeze() and tick_unfreeze()
to catch when timekeeping is suspended and resumed during suspend-to-idle
so as to be able to check whether or not we enter the "frozen" state
and to measure the time spent in it.
Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
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It was noted that the 32bit implementation of ktime_divns()
was doing unsigned division and didn't properly handle
negative values.
And when a ktime helper was changed to utilize
ktime_divns, it caused a regression on some IR blasters.
See the following bugzilla for details:
https://bugzilla.redhat.com/show_bug.cgi?id=1200353
This patch fixes the problem in ktime_divns by checking
and preserving the sign bit, and then reapplying it if
appropriate after the division, it also changes the return
type to a s64 to make it more obvious this is expected.
Nicolas also pointed out that negative dividers would
cause infinite loops on 32bit systems, negative dividers
is unlikely for users of this function, but out of caution
this patch adds checks for negative dividers for both
32-bit (BUG_ON) and 64-bit(WARN_ON) versions to make sure
no such use cases creep in.
[ tglx: Hand an u64 to do_div() to avoid the compiler warning ]
Fixes: 166afb64511e 'ktime: Sanitize ktime_to_us/ms conversion'
Reported-and-tested-by: Trevor Cordes <[email protected]>
Signed-off-by: John Stultz <[email protected]>
Acked-by: Nicolas Pitre <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Josh Boyer <[email protected]>
Cc: One Thousand Gnomes <[email protected]>
Cc: <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Thomas Gleixner:
"A simple fix to actually shut down a detached device instead of
keeping it active"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clockevents: Shutdown detached clockevent device
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Recent optimizations were made to thread_group_cputimer to improve its
scalability by keeping track of cputime stats without a lock. However,
the values were open coded to the structure, causing them to be at
a different abstraction level from the regular task_cputime structure.
Furthermore, any subsequent similar optimizations would not be able to
share the new code, since they are specific to thread_group_cputimer.
This patch adds the new task_cputime_atomic data structure (introduced in
the previous patch in the series) to thread_group_cputimer for keeping
track of the cputime atomically, which also helps generalize the code.
Suggested-by: Ingo Molnar <[email protected]>
Signed-off-by: Jason Low <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Aswin Chandramouleeswaran <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Scott J Norton <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Waiman Long <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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improve scalability
While running a database workload, we found a scalability issue with itimers.
Much of the problem was caused by the thread_group_cputimer spinlock.
Each time we account for group system/user time, we need to obtain a
thread_group_cputimer's spinlock to update the timers. On larger systems
(such as a 16 socket machine), this caused more than 30% of total time
spent trying to obtain this kernel lock to update these group timer stats.
This patch converts the timers to 64-bit atomic variables and use
atomic add to update them without a lock. With this patch, the percent
of total time spent updating thread group cputimer timers was reduced
from 30% down to less than 1%.
Note: On 32-bit systems using the generic 64-bit atomics, this causes
sample_group_cputimer() to take locks 3 times instead of just 1 time.
However, we tested this patch on a 32-bit system ARM system using the
generic atomics and did not find the overhead to be much of an issue.
An explanation for why this isn't an issue is that 32-bit systems usually
have small numbers of CPUs, and cacheline contention from extra spinlocks
called periodically is not really apparent on smaller systems.
Signed-off-by: Jason Low <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Aswin Chandramouleeswaran <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Scott J Norton <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Waiman Long <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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READ_ONCE()/WRITE_ONCE()
ACCESS_ONCE doesn't work reliably on non-scalar types. This patch removes
the rest of the existing usages of ACCESS_ONCE() in the scheduler, and use
the new READ_ONCE() and WRITE_ONCE() APIs as appropriate.
Signed-off-by: Jason Low <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Acked-by: Waiman Long <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Aswin Chandramouleeswaran <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Scott J Norton <[email protected]>
Cc: Steven Rostedt <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Simon Horman reported this crash on a system with
high-res timers disabled but nohz enabled:
> ------------[ cut here ]------------
> kernel BUG at kernel/irq_work.c:135!
BUG_ON(!irqs_disabled());
So something enabled interrupts in the periodic tick handling machinery,
and that code path indeed has a local_irq_disable()/enable pair in
tick_nohz_switch_to_nohz() which causes havoc. Fix it.
This patch also fixes a +nohz -hrtimers hang reported by Ingo Molnar.
Reported-by: Simon Horman <[email protected]>
Reported-by: Ingo Molnar <[email protected]>
Tested-by: Simon Horman <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: LAK <[email protected]>
Cc: Magnus Damm <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1505071425520.4225@nanos
Signed-off-by: Ingo Molnar <[email protected]>
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unused
The hrtimer callback in the hrtimer's tick broadcast code sometimes
incorrectly ends up scheduling events at the current tick causing the
kernel to hang servicing the same hrtimer forever. This typically
happens when a device is swapped out by
tick_install_broadcast_device(), which replaces the event handler with
clock_events_handle_noop() and sets the device mode to
CLOCK_EVT_MODE_UNUSED. If the timer is scheduled when this happens,
the next_event field will not be updated and the hrtimer ends up being
restarted at the current tick. To prevent this from happening, only
try to restart the hrtimer if the broadcast clock event device is in
one of the active modes and try to cancel the timer when entering the
CLOCK_EVT_MODE_UNUSED mode.
Signed-off-by: Andreas Sandberg <[email protected]>
Tested-by: Catalin Marinas <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Reviewed-by: Preeti U Murthy <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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At present, internal_add_timer() examines flags with 'base' which doesn't
contain flags. Examine with 'timer->base' to avoid unnecessary waking up
of nohz CPU when timer base has TIMER_DEFERRABLE set.
Signed-off-by: Joonwoo Park <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: John Stultz <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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Today the number of bits of the broadcast masks that is output into
/proc/timer_list is sizeof(unsigned long). This means that on machines
with a larger number of CPUs, the bitmasks of CPUs beyond this range do
not appear.
Fix this by using bitmap printing through "%*pb" instead, so as to
output the broadcast masks for the range of nr_cpu_ids into
/proc/timer_list.
Signed-off-by: Preeti U Murthy <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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Simplify the oneshot logic by avoiding the reprogramming loops. That
also allows to call the cpu local handler outside of the
broadcast_lock held region.
Tested-by: Borislav Petkov <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
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With the removal of the hrtimer softirq the switch to highres/nohz
mode happens in the tick interrupt. That leads to a livelock when the
per cpu event handler is directly called from the broadcast handler
under broadcast lock because broadcast lock needs to be taken for the
highres/nohz switch as well.
Solve this by calling the cpu local handler outside the broadcast_lock
held region.
Fixes: c6eb3f70d448 "hrtimer: Get rid of hrtimer softirq"
Reported-and-tested-by: Borislav Petkov <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
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A clockevent device is marked DETACHED when it is replaced by another
clockevent device.
The device is shutdown properly for drivers that implement legacy
->set_mode() callback, as we call ->set_mode() for CLOCK_EVT_MODE_UNUSED
as well.
But for the new per-state callback interface, we skip shutting down the
device, as we thought its an internal state change. That wasn't correct.
The effect is that the device is left programmed in oneshot or periodic
mode.
Fall-back to 'case CLOCK_EVT_STATE_SHUTDOWN', to shutdown the device.
Fixes: bd624d75db21 "clockevents: Introduce mode specific callbacks"
Reported-by: Daniel Lezcano <[email protected]>
Signed-off-by: Viresh Kumar <[email protected]>
Cc: [email protected]
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/eef0a91c51b74d4e52c8e5a95eca27b5a0563f07.1428650683.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <[email protected]>
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Because we drop cpu_base->lock around calling hrtimer::function, it is
possible for hrtimer_start() to come in between and enqueue the timer.
If hrtimer::function then returns HRTIMER_RESTART we'll hit the BUG_ON
because HRTIMER_STATE_ENQUEUED will be set.
Since the above is a perfectly valid scenario, remove the BUG_ON and
make the enqueue_hrtimer() call conditional on the timer not being
enqueued already.
NOTE: in that concurrent scenario its entirely common for both sites
to want to modify the hrtimer, since hrtimers don't provide
serialization themselves be sure to provide some such that the
hrtimer::function and the hrtimer_start() caller don't both try and
fudge the expiration state at the same time.
To that effect, add a WARN when someone tries to forward an already
enqueued timer, the most common way to change the expiry of self
restarting timers. Ideally we'd put the WARN in everything modifying
the expiry but most of that is inlines and we don't need the bloat.
Fixes: 2d44ae4d7135 ("hrtimer: clean up cpu->base locking tricks")
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Ben Segall <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Paul Turner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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do_usleep_range() and schedule_hrtimeout_range() are __sched as
well. So it makes no sense to have the exported function in a
different section.
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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The only user ignores it anyway and rightfully so.
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Preeti U Murthy <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
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