Commit Graph

891 Commits

Author SHA1 Message Date
Frederic Weisbecker
3d36aebc2e nohz: Support nohz full remote kick
Remotely kicking a full nohz CPU in order to make it re-evaluate its
next tick is currently implemented using the scheduler IPI.

However this bloats a scheduler fast path with an off-topic feature.
The scheduler tick was abused here for its cool "callable
anywhere/anytime" properties.

But now that the irq work subsystem can queue remote callbacks, it's
a perfect fit to safely queue IPIs when interrupts are disabled
without worrying about concurrent callers.

So lets implement remote kick on top of irq work. This is going to
be used when a new event requires the next tick to be recalculated:
more than 1 task competing on the CPU, timer armed, ...

Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-06-16 16:26:54 +02:00
Linus Torvalds
00170fdd08 Merge branch 'akpm' (patchbomb from Andrew) into next
Merge misc updates from Andrew Morton:

 - a few fixes for 3.16.  Cc'ed to stable so they'll get there somehow.

 - various misc fixes and cleanups

 - most of the ocfs2 queue.  Review is slow...

 - most of MM.  The MM queue is pretty huge this time, but not much in
   the way of feature work.

 - some tweaks under kernel/

 - printk maintenance work

 - updates to lib/

 - checkpatch updates

 - tweaks to init/

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (276 commits)
  fs/autofs4/dev-ioctl.c: add __init to autofs_dev_ioctl_init
  fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul
  init/main.c: remove an ifdef
  kthreads: kill CLONE_KERNEL, change kernel_thread(kernel_init) to avoid CLONE_SIGHAND
  init/main.c: add initcall_blacklist kernel parameter
  init/main.c: don't use pr_debug()
  fs/binfmt_flat.c: make old_reloc() static
  fs/binfmt_elf.c: fix bool assignements
  fs/efs: convert printk(KERN_DEBUG to pr_debug
  fs/efs: add pr_fmt / use __func__
  fs/efs: convert printk to pr_foo()
  scripts/checkpatch.pl: device_initcall is not the only __initcall substitute
  checkpatch: check stable email address
  checkpatch: warn on unnecessary void function return statements
  checkpatch: prefer kstrto<foo> to sscanf(buf, "%<lhuidx>", &bar);
  checkpatch: add warning for kmalloc/kzalloc with multiply
  checkpatch: warn on #defines ending in semicolon
  checkpatch: make --strict a default for files in drivers/net and net/
  checkpatch: always warn on missing blank line after variable declaration block
  checkpatch: fix wildcard DT compatible string checking
  ...
2014-06-04 16:55:13 -07:00
John Stultz
6d9bcb621b timekeeping: use printk_deferred when holding timekeeping seqlock
Jiri Bohac pointed out that there are rare but potential deadlock
possibilities when calling printk while holding the timekeeping
seqlock.

This is due to printk() triggering console sem wakeup, which can
cause scheduling code to trigger hrtimers which may try to read
the time.

Specifically, as Jiri pointed out, that path is:
  printk
    vprintk_emit
      console_unlock
        up(&console_sem)
          __up
	    wake_up_process
	      try_to_wake_up
	        ttwu_do_activate
		  ttwu_activate
		    activate_task
		      enqueue_task
		        enqueue_task_fair
			  hrtick_update
			    hrtick_start_fair
			      hrtick_start_fair
			        get_time
				  ktime_get
				    --> endless loop on
				    read_seqcount_retry(&timekeeper_seq, ...)

This patch tries to avoid this issue by using printk_deferred (previously
named printk_sched) which should defer printing via a irq_work_queue.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Reported-by: Jiri Bohac <jbohac@suse.cz>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:54:17 -07:00
George Spelvin
ea54bca3aa ntp: Make is_error_status() use its argument
is_error_status() is an inline function always called with the
global time_status as an argument, so there's zero functional
difference with this change, but the non-CONFIG_NTP_PPS version
uses the passed-in argument, while the CONFIG_NTP_PPS one ignores
its argument and uses the global.

Looks like is_error_status was refactored out, but someone forgot
to change the logic to check the local argument value.

Thus this patch makes it use the argument always; shorter variable
names are good.

Signed-off-by: George Spelvin <linux@horizon.com>
[jstultz: Tweaked commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-05-12 11:01:08 -07:00
Fabian Frederick
cdafb93feb ntp: Convert simple_strtol to kstrtol
Replace obsolete function simple_strtol w/ kstrtol

Inspired-By: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
[jstultz: Tweak commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-05-12 10:09:25 -07:00
Stephen Boyd
c04ae71c9c sched_clock: Remove deprecated setup_sched_clock() API
Remove the 32-bit only setup_sched_clock() API now that all users
have been converted to the 64-bit friendly sched_clock_register().

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-04-22 13:38:33 -07:00
Viresh Kumar
27630532ef tick-sched: Check tick_nohz_enabled in tick_nohz_switch_to_nohz()
Since commit d689fe222 (NOHZ: Check for nohz active instead of nohz
enabled) the tick_nohz_switch_to_nohz() function returns because it
checks for the tick_nohz_active flag. This can't be set, because the
function itself sets it.

Undo the change in tick_nohz_switch_to_nohz().

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Cc: Arvind.Chauhan@arm.com
Cc: linaro-networking@linaro.org
Cc: <stable@vger.kernel.org> # 3.13+
Link: http://lkml.kernel.org/r/40939c05f2d65d781b92b20302b02243d0654224.1397537987.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-04-15 20:26:58 +02:00
Viresh Kumar
03e6bdc5c4 tick-sched: Don't call update_wall_time() when delta is lesser than tick_period
In tick_do_update_jiffies64() we are processing ticks only if delta is
greater than tick_period. This is what we are supposed to do here and
it broke a bit with this patch:

commit 47a1b796 (tick/timekeeping: Call update_wall_time outside the
jiffies lock)

With above patch, we might end up calling update_wall_time() even if
delta is found to be smaller that tick_period. Fix this by returning
when the delta is less than tick period.

[ tglx: Made it a 3 liner and massaged changelog ]

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Cc: Arvind.Chauhan@arm.com
Cc: linaro-networking@linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Cc: <stable@vger.kernel.org> # v3.14+
Link: http://lkml.kernel.org/r/80afb18a494b0bd9710975bcc4de134ae323c74f.1397537987.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-04-15 20:26:45 +02:00
Viresh Kumar
521c42990e tick-common: Fix wrong check in tick_check_replacement()
tick_check_replacement() returns if a replacement of clock_event_device is
possible or not. It does this as the first check:

	if (tick_check_percpu(curdev, newdev, smp_processor_id()))
		return false;

Thats wrong. tick_check_percpu() returns true when the device is
useable. Check for false instead.

[ tglx: Massaged changelog ]

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: <stable@vger.kernel.org> # v3.11+
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Cc: Arvind.Chauhan@arm.com
Cc: linaro-networking@linaro.org
Link: http://lkml.kernel.org/r/486a02efe0246635aaba786e24b42d316438bf3b.1397537987.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-04-15 20:26:44 +02:00
Gideon Israel Dsouza
52f5684c8e kernel: use macros from compiler.h instead of __attribute__((...))
To increase compiler portability there is <linux/compiler.h> which
provides convenience macros for various gcc constructs.  Eg: __weak for
__attribute__((weak)).  I've replaced all instances of gcc attributes
with the right macro in the kernel subsystem.

Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:36:11 -07:00
Linus Torvalds
1ead658124 Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer changes from Thomas Gleixner:
 "This assorted collection provides:

   - A new timer based timer broadcast feature for systems which do not
     provide a global accessible timer device.  That allows those
     systems to put CPUs into deep idle states where the per cpu timer
     device stops.

   - A few NOHZ_FULL related improvements to the timer wheel

   - The usual updates to timer devices found in ARM SoCs

   - Small improvements and updates all over the place"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
  tick: Remove code duplication in tick_handle_periodic()
  tick: Fix spelling mistake in tick_handle_periodic()
  x86: hpet: Use proper destructor for delayed work
  workqueue: Provide destroy_delayed_work_on_stack()
  clocksource: CMT, MTU2, TMU and STI should depend on GENERIC_CLOCKEVENTS
  timer: Remove code redundancy while calling get_nohz_timer_target()
  hrtimer: Rearrange comments in the order struct members are declared
  timer: Use variable head instead of &work_list in __run_timers()
  clocksource: exynos_mct: silence a static checker warning
  arm: zynq: Add support for cpufreq
  arm: zynq: Don't use arm_global_timer with cpufreq
  clocksource/cadence_ttc: Overhaul clocksource frequency adjustment
  clocksource/cadence_ttc: Call clockevents_update_freq() with IRQs enabled
  clocksource: Add Kconfig entries for CMT, MTU2, TMU and STI
  sh: Remove Kconfig entries for TMU, CMT and MTU2
  ARM: shmobile: Remove CMT, TMU and STI Kconfig entries
  clocksource: armada-370-xp: Use atomic access for shared registers
  clocksource: orion: Use atomic access for shared registers
  clocksource: timer-keystone: Delete unnecessary variable
  clocksource: timer-keystone: introduce clocksource driver for Keystone
  ...
2014-04-01 11:00:07 -07:00
John Stultz
cab5e127ee time: Revert to calling clock_was_set_delayed() while in irq context
In commit 47a1b79630 ("tick/timekeeping: Call
update_wall_time outside the jiffies lock"), we moved to calling
clock_was_set() due to the fact that we were no longer holding
the timekeeping or jiffies lock.

However, there is still the problem that clock_was_set()
triggers an IPI, which cannot be done from the timer's hard irq
context, and will generate WARN_ON warnings.

Apparently in my earlier testing, I'm guessing I didn't bump the
dmesg log level, so I somehow missed the WARN_ONs.

Thus we need to revert back to calling clock_was_set_delayed().

Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1395963049-11923-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-03-28 08:07:07 +01:00
Viresh Kumar
b97f0291a2 tick: Remove code duplication in tick_handle_periodic()
tick_handle_periodic() is calling ktime_add() at two places, first before the
infinite loop and then at the end of infinite loop. We can rearrange code a bit
to fix code duplication here.

It looks quite simple and shouldn't break anything, I guess :)

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: fweisbec@gmail.com
Link: http://lkml.kernel.org/r/be3481e8f3f71df694a4b43623254fc93ca51b59.1395735873.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-26 00:56:49 +01:00
Viresh Kumar
cacb3c76c2 tick: Fix spelling mistake in tick_handle_periodic()
One of the comments in tick_handle_periodic() had 'when' instead of 'which' (My
guess :)). Fix it.

Also fix spelling mistake in 'Possible'.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linaro-kernel@lists.linaro.org
Cc: skarafotis@gmail.com
Link: http://lkml.kernel.org/r/2b29ca4230c163e44179941d7c7a16c1474385c2.1395743878.git.viresh.kumar@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-26 00:56:49 +01:00
Thomas Gleixner
f9a8a0abc3 Merge branch 'fortglx/3.15/time' of git://git.linaro.org/people/john.stultz/linux into timers/core
- support CLOCK_BOOTTIME clock in timerfd
 - Add missing header file

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-10 19:53:09 +01:00
Rashika Kheria
64e8d20bd3 kernel: Include appropriate header file in time/timekeeping_debug.c
Include appropriate header file kernel/time/timekeeping_internal.h in
kernel/time/timekeeping_debug.c because it has prototype declaration of
function defined in kernel/time/timekeeping_debug.c.

This eliminates the following warning in
kernel/time/timekeeping_debug.c:
kernel/time/timekeeping_debug.c:68:6: warning: no previous prototype for ‘tk_debug_account_sleep_time’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-03-02 20:52:58 -08:00
Stephen Boyd
5ae8aabeae sched_clock: Prevent callers from seeing half-updated data
The generic sched_clock registration function was previously
done lockless, due to the fact that it was expected to be called
only once. However, now there are systems that may register
multiple sched_clock sources, for which the lack of locking has
casued problems:

If two sched_clock sources are registered we may end up in a
situation where a call to sched_clock() may be accessing the
epoch cycle count for the old counter and the cycle count for the
new counter. This can lead to confusing results where
sched_clock() values jump and then are reset to 0 (due to the way
the registration function forces the epoch_ns to be 0).

Fix this by reorganizing the registration function to hold the
seqlock for as short a time as possible while we update the
clock_data structure for a new counter. We also put any
accumulated time into epoch_ns instead of resetting the time to
0 so that the clock doesn't reset after each successful
registration.

[jstultz: Added extra context to the commit message]

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Cartwright <joshc@codeaurora.org>
Link: http://lkml.kernel.org/r/1392662736-7803-2-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-19 17:07:22 +01:00
Paul Gortmaker
f96a34e27d nohz: ensure users are aware boot CPU is not NO_HZ_FULL
This bit of information is in the Kconfig help text:

  "Note the boot CPU will still be kept outside the range to
  handle the timekeeping duty."

However neither the variable NO_HZ_FULL_ALL, or the prompt
convey this important detail, so lets add it to the prompt
to make it more explicitly obvious to the average user.

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1391711781-7466-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-02-14 17:59:17 +01:00
Thomas Gleixner
dd5fd9b91a tick: Clear broadcast pending bit when switching to oneshot
AMD systems which use the C1E workaround in the amd_e400_idle routine
trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU.

The reason is that the idle routine of those AMD systems switches the
cpu into forced broadcast mode early on before the newly brought up
CPU can switch over to high resolution / NOHZ mode. The timer related
CPU1 bringup looks like this:

  clockevent_register_device(local_apic);
  tick_setup(local_apic);
  ...
  idle()
	tick_broadcast_on_off(FORCE);
	tick_broadcast_oneshot_control(ENTER)
	  cpumask_set(cpu, broadcast_oneshot_mask);
	halt();

Now the broadcast interrupt on CPU0 sets CPU1 in the
broadcast_pending_mask and wakes CPU1. So CPU1 continues:

	local_apic_timer_interrupt()
	   tick_handle_periodic();
	   softirq()
	     tick_init_highres();
	       cpumask_clr(cpu, broadcast_oneshot_mask);
	
	tick_broadcast_oneshot_control(ENTER)
	   WARN_ON(cpumask_test(cpu, broadcast_pending_mask);

So while we remove CPU1 from the broadcast_oneshot_mask when we switch
over to highres mode, we do not clear the pending bit, which then
triggers the warning when we go back to idle.

The reason why this is only visible on C1E affected AMD systems is
that the other machines enter the deep sleep states via
acpi_idle/intel_idle and exit the broadcast mode before executing the
remote triggered local_apic_timer_interrupt. So the pending bit is
already cleared when the switch over to highres mode is clearing the
oneshot mask.

The solution is simple: Clear the pending bit together with the mask
bit when we switch over to highres mode.

Stanislaw came up independently with the same patch by enforcing the
C1E workaround and debugging the fallout. I picked mine, because mine
has a changelog :)

Reported-by: poma <pomidorabelisima@gmail.com>
Debugged-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Dave Jones <davej@redhat.com>
Cc: Justin M. Forbes <jforbes@redhat.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402111434180.21991@ionos.tec.linutronix.de
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-13 21:55:54 +01:00
Preeti U Murthy
849401b66d tick: Fixup more fallout from hrtimer broadcast mode
The hrtimer mode of broadcast is supported only when
GENERIC_CLOCKEVENTS_BROADCAST and TICK_ONESHOT config options
are enabled. Hence compile in the functions for hrtimer mode
of broadcast only when these options are selected.
Also fix max_delta_ticks value for the pseudo clock device.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/52F719EE.9010304@linux.vnet.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-09 15:11:47 +01:00
Thomas Gleixner
f1689bb7ab time: Fixup fallout from recent clockevent/tick changes
Make the stub function static inline instead of static and move the
clockevents related function into the proper ifdeffed section.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
2014-02-07 16:00:46 +01:00
Preeti U Murthy
5d1638acb9 tick: Introduce hrtimer based broadcast
On some architectures, in certain CPU deep idle states the local timers stop.
An external clock device is used to wakeup these CPUs. The kernel support for the
wakeup of these CPUs is provided by the tick broadcast framework by using the
external clock device as the wakeup source.

However not all implementations of architectures provide such an external
clock device. This patch includes support in the broadcast framework to handle
the wakeup of the CPUs in deep idle states on such systems by queuing a hrtimer
on one of the CPUs, which is meant to handle the wakeup of CPUs in deep idle states.

This patchset introduces a pseudo clock device which can be registered by the
archs as tick_broadcast_device in the absence of a real external clock
device. Once registered, the broadcast framework will work as is for these
architectures as long as the archs take care of the BROADCAST_ENTER
notification failing for one of the CPUs. This CPU is made the stand by CPU to
handle wakeup of the CPUs in deep idle and it *must not enter deep idle states*.

The CPU with the earliest wakeup is chosen to be this CPU. Hence this way the
stand by CPU dynamically moves around and so does the hrtimer which is queued
to trigger at the next earliest wakeup time. This is consistent with the case where
an external clock device is present. The smp affinity of this clock device is
set to the CPU with the earliest wakeup. This patchset handles the hotplug of
the stand by CPU as well by moving the hrtimer on to the CPU handling the CPU_DEAD
notification.

Originally-from: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: deepthi@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: paulus@samba.org
Cc: srivatsa.bhat@linux.vnet.ibm.com
Cc: svaidy@linux.vnet.ibm.com
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: rafael.j.wysocki@intel.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20140207080632.17187.80532.stgit@preeti.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-07 15:34:29 +01:00
Preeti U Murthy
da7e6f45c3 time: Change the return type of clockevents_notify() to integer
The broadcast framework can potentially be made use of by archs which do not have an
external clock device as well. Then, it is required that one of the CPUs need
to handle the broadcasting of wakeup IPIs to the CPUs in deep idle. As a
result its local timers should remain functional all the time. For such
a CPU, the BROADCAST_ENTER notification has to fail indicating that its clock
device cannot be shutdown. To make way for this support, change the return
type of tick_broadcast_oneshot_control() and hence clockevents_notify() to
indicate such scenarios.

Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: deepthi@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: paulus@samba.org
Cc: srivatsa.bhat@linux.vnet.ibm.com
Cc: svaidy@linux.vnet.ibm.com
Cc: peterz@infradead.org
Cc: benh@kernel.crashing.org
Cc: rafael.j.wysocki@intel.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20140207080606.17187.78306.stgit@preeti.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-07 15:34:29 +01:00
Soren Brinkmann
fe79a9ba11 clockevents: Adjust timer interval when frequency changes
clockevent devices in periodic mode are not updated when the frequency
of the device changes. Issue a dev->set_mode() callback which forces
the device to reevaluate the timer settings.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-3-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-07 15:34:29 +01:00
Thomas Gleixner
627ee7947e clockevents: Serialize calls to clockevents_update_freq() in the core
We can identify the broadcast device in the core and serialize all
callers including interrupts on a different CPU against the update.
Also, disabling interrupts is moved into the core allowing callers to
leave interrutps enabled when calling clockevents_update_freq().

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-07 15:34:28 +01:00
Shaibal Dutta
e8b175946c timekeeping: Move clock sync work to power efficient workqueue
For better use of CPU idle time, allow the scheduler to select the CPU
on which the CMOS clock sync work would be scheduled. This improves
idle residency time and conserver power.

This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected.

Signed-off-by: Shaibal Dutta <shaibal.dutta@broadcom.com>
[zoran.markovic@linaro.org: Added commit message. Aligned code.]
Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1391195904-12497-1-git-send-email-zoran.markovic@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-07 15:34:28 +01:00
Mikulas Patocka
80d767d770 time: Fix overflow when HZ is smaller than 60
When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.

This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
  .mult  = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
  ^

This patch reduces the JIFFIES_SHIFT value to avoid the overflow.

Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-02-06 16:01:40 +01:00
Ingo Molnar
a2b4c607c9 Merge branch 'timers/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/urgent
Pull dynticks cleanups from Frederic Weisbecker.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-25 08:27:26 +01:00
Linus Torvalds
6c64614356 Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer changes from Ingo Molnar:
  - ARM clocksource/clockevent improvements and fixes
  - generic timekeeping updates: TAI fixes/improvements, cleanups
  - Posix cpu timer cleanups and improvements
  - dynticks updates: full dynticks bugfixes, optimizations and cleanups

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits)
  clocksource: Timer-sun5i: Switch to sched_clock_register()
  timekeeping: Remove comment that's mostly out of date
  rtc-cmos: Add an alarm disable quirk
  timekeeper: fix comment typo for tk_setup_internals()
  timekeeping: Fix missing timekeeping_update in suspend path
  timekeeping: Fix CLOCK_TAI timer/nanosleep delays
  tick/timekeeping: Call update_wall_time outside the jiffies lock
  timekeeping: Avoid possible deadlock from clock_was_set_delayed
  timekeeping: Fix potential lost pv notification of time change
  timekeeping: Fix lost updates to tai adjustment
  clocksource: sh_cmt: Add clk_prepare/unprepare support
  clocksource: bcm_kona_timer: Remove unused bcm_timer_ids
  clocksource: vt8500: Remove deprecated IRQF_DISABLED
  clocksource: tegra: Remove deprecated IRQF_DISABLED
  clocksource: misc drivers: Remove deprecated IRQF_DISABLED
  clocksource: sh_mtu2: Remove unnecessary platform_set_drvdata()
  clocksource: sh_tmu: Remove unnecessary platform_set_drvdata()
  clocksource: armada-370-xp: Enable timer divider only when needed
  clocksource: clksrc-of: Warn if no clock sources are found
  clocksource: orion: Switch to sched_clock_register()
  ...
2014-01-20 11:34:26 -08:00
Linus Torvalds
a0fa1dd3cd Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes from Ingo Molnar:

 - Add the initial implementation of SCHED_DEADLINE support: a real-time
   scheduling policy where tasks that meet their deadlines and
   periodically execute their instances in less than their runtime quota
   see real-time scheduling and won't miss any of their deadlines.
   Tasks that go over their quota get delayed (Available to privileged
   users for now)

 - Clean up and fix preempt_enable_no_resched() abuse all around the
   tree

 - Do sched_clock() performance optimizations on x86 and elsewhere

 - Fix and improve auto-NUMA balancing

 - Fix and clean up the idle loop

 - Apply various cleanups and fixes

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
  sched: Fix __sched_setscheduler() nice test
  sched: Move SCHED_RESET_ON_FORK into attr::sched_flags
  sched: Fix up attr::sched_priority warning
  sched: Fix up scheduler syscall LTP fails
  sched: Preserve the nice level over sched_setscheduler() and sched_setparam() calls
  sched/core: Fix htmldocs warnings
  sched/deadline: No need to check p if dl_se is valid
  sched/deadline: Remove unused variables
  sched/deadline: Fix sparse static warnings
  m68k: Fix build warning in mac_via.h
  sched, thermal: Clean up preempt_enable_no_resched() abuse
  sched, net: Fixup busy_loop_us_clock()
  sched, net: Clean up preempt_enable_no_resched() abuse
  sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding
  sched/preempt, locking: Rework local_bh_{dis,en}able()
  sched/clock, x86: Avoid a runtime condition in native_sched_clock()
  sched/clock: Fix up clear_sched_clock_stable()
  sched/clock, x86: Use a static_key for sched_clock_stable
  sched/clock: Remove local_irq_disable() from the clocks
  sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs
  ...
2014-01-20 10:42:08 -08:00
Alex Shi
e9a2eb403b nohz_full: fix code style issue of tick_nohz_full_stop_tick
Code usually starts with 'tab' instead of 7 'space' in kernel

Signed-off-by: Alex Shi <alex.shi@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1386074112-30754-2-git-send-email-alex.shi@linaro.org
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-01-15 23:07:11 +01:00
Frederic Weisbecker
855a0fc30b nohz: Get timekeeping max deferment outside jiffies_lock
We don't need to fetch the timekeeping max deferment under the
jiffies_lock seqlock.

If the clocksource is updated concurrently while we stop the tick,
stop machine is called and the tick will be reevaluated again along with
uptodate jiffies and its related values.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1387320692-28460-9-git-send-email-fweisbec@gmail.com
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-01-15 23:07:11 +01:00
Frederic Weisbecker
5acac1be49 tick: Rename tick_check_idle() to tick_irq_enter()
This makes the code more symetric against the existing tick functions
called on irq exit: tick_irq_exit() and tick_nohz_irq_exit().

These function are also symetric as they mirror each other's action:
we start to account idle time on irq exit and we stop this accounting
on irq entry. Also the tick is stopped on irq exit and timekeeping
catches up with the tickless time elapsed until we reach irq entry.

This rename was suggested by Peter Zijlstra a long while ago but it
got forgotten in the mass.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1387320692-28460-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-01-15 23:05:31 +01:00
Peter Zijlstra
35af99e646 sched/clock, x86: Use a static_key for sched_clock_stable
In order to avoid the runtime condition and variable load turn
sched_clock_stable into a static_key.

Also provide a shorter implementation of local_clock() and
cpu_clock(int) when sched_clock_stable==1.

                        MAINLINE   PRE       POST

    sched_clock_stable: 1          1         1
    (cold) sched_clock: 329841     221876    215295
    (cold) local_clock: 301773     234692    220773
    (warm) sched_clock: 38375      25602     25659
    (warm) local_clock: 100371     33265     27242
    (warm) rdtsc:       27340      24214     24208
    sched_clock_stable: 0          0         0
    (cold) sched_clock: 382634     235941    237019
    (cold) local_clock: 396890     297017    294819
    (warm) sched_clock: 38194      25233     25609
    (warm) local_clock: 143452     71234     71232
    (warm) rdtsc:       27345      24245     24243

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-eummbdechzz37mwmpags1gjr@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-13 15:13:13 +01:00
Ingo Molnar
d05d24a984 Merge branch 'fortglx/3.14/time' of git://git.linaro.org/people/john.stultz/linux into timers/core
Pull timekeeping updates from John Stultz.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-12 14:13:31 +01:00
Ingo Molnar
dba861461f Merge branch 'linus' into timers/core
Pick up the latest fixes and refresh the branch.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-12 14:12:44 +01:00
John Stultz
7a06c41cbe sched_clock: Disable seqlock lockdep usage in sched_clock()
Unfortunately the seqlock lockdep enablement can't be used
in sched_clock(), since the lockdep infrastructure eventually
calls into sched_clock(), which causes a deadlock.

Thus, this patch changes all generic sched_clock() usage
to use the raw_* methods.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Reported-by: Krzysztof Hałasa <khalasa@piap.pl>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1388704274-5278-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-01-12 10:14:00 +01:00
John Stultz
38aef31ce7 timekeeping: Remove comment that's mostly out of date
Prior to 92bb1fcf57 (Only
do nanosecond rounding on GENERIC_TIME_VSYSCALL_OLD
systems), the comment here was accuate, but now we can
mostly avoid the extra rounding which causes the unlikey
to be actually likely here.

So remove the out of date comment.

Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 12:53:22 -08:00
Yijing Wang
d26e4fe0db timekeeper: fix comment typo for tk_setup_internals()
Fix trivial comment typo for tk_setup_internals().

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 11:54:35 -08:00
John Stultz
330a1617b0 timekeeping: Fix missing timekeeping_update in suspend path
Since 48cdc135d4 (Implement a shadow timekeeper), we have to
call timekeeping_update() after any adjustment to the timekeeping
structure in order to make sure that any adjustments to the structure
persist.

In the timekeeping suspend path, we udpate the timekeeper
structure, so we should be sure to update the shadow-timekeeper
before releasing the timekeeping locks. Currently this isn't done.

In most cases, the next time related code to run would be
timekeeping_resume, which does update the shadow-timekeeper, but
in an abundence of caution, this patch adds the call to
timekeeping_update() in the suspend path.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 11:54:35 -08:00
John Stultz
04005f6011 timekeeping: Fix CLOCK_TAI timer/nanosleep delays
A think-o in the calculation of the monotonic -> tai time offset
results in CLOCK_TAI timers and nanosleeps to expire late (the
latency is ~2x the tai offset).

Fix this by adding the tai offset from the realtime offset instead
of subtracting.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 11:54:34 -08:00
John Stultz
47a1b79630 tick/timekeeping: Call update_wall_time outside the jiffies lock
Since the xtime lock was split into the timekeeping lock and
the jiffies lock, we no longer need to call update_wall_time()
while holding the jiffies lock.

Thus, this patch splits update_wall_time() out from do_timer().

This allows us to get away from calling clock_was_set_delayed()
in update_wall_time() and instead use the standard clock_was_set()
call that previously would deadlock, as it causes the jiffies lock
to be acquired.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 11:54:32 -08:00
John Stultz
6fdda9a9c5 timekeeping: Avoid possible deadlock from clock_was_set_delayed
As part of normal operaions, the hrtimer subsystem frequently calls
into the timekeeping code, creating a locking order of
  hrtimer locks -> timekeeping locks

clock_was_set_delayed() was suppoed to allow us to avoid deadlocks
between the timekeeping the hrtimer subsystem, so that we could
notify the hrtimer subsytem the time had changed while holding
the timekeeping locks. This was done by scheduling delayed work
that would run later once we were out of the timekeeing code.

But unfortunately the lock chains are complex enoguh that in
scheduling delayed work, we end up eventually trying to grab
an hrtimer lock.

Sasha Levin noticed this in testing when the new seqlock lockdep
enablement triggered the following (somewhat abrieviated) message:

[  251.100221] ======================================================
[  251.100221] [ INFO: possible circular locking dependency detected ]
[  251.100221] 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053 Not tainted
[  251.101967] -------------------------------------------------------
[  251.101967] kworker/10:1/4506 is trying to acquire lock:
[  251.101967]  (timekeeper_seq){----..}, at: [<ffffffff81160e96>] retrigger_next_event+0x56/0x70
[  251.101967]
[  251.101967] but task is already holding lock:
[  251.101967]  (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70
[  251.101967]
[  251.101967] which lock already depends on the new lock.
[  251.101967]
[  251.101967]
[  251.101967] the existing dependency chain (in reverse order) is:
[  251.101967]
-> #5 (hrtimer_bases.lock#11){-.-...}:
[snipped]
-> #4 (&rt_b->rt_runtime_lock){-.-...}:
[snipped]
-> #3 (&rq->lock){-.-.-.}:
[snipped]
-> #2 (&p->pi_lock){-.-.-.}:
[snipped]
-> #1 (&(&pool->lock)->rlock){-.-...}:
[  251.101967]        [<ffffffff81194803>] validate_chain+0x6c3/0x7b0
[  251.101967]        [<ffffffff81194d9d>] __lock_acquire+0x4ad/0x580
[  251.101967]        [<ffffffff81194ff2>] lock_acquire+0x182/0x1d0
[  251.101967]        [<ffffffff84398500>] _raw_spin_lock+0x40/0x80
[  251.101967]        [<ffffffff81153e69>] __queue_work+0x1a9/0x3f0
[  251.101967]        [<ffffffff81154168>] queue_work_on+0x98/0x120
[  251.101967]        [<ffffffff81161351>] clock_was_set_delayed+0x21/0x30
[  251.101967]        [<ffffffff811c4bd1>] do_adjtimex+0x111/0x160
[  251.101967]        [<ffffffff811e2711>] compat_sys_adjtimex+0x41/0x70
[  251.101967]        [<ffffffff843a4b49>] ia32_sysret+0x0/0x5
[  251.101967]
-> #0 (timekeeper_seq){----..}:
[snipped]
[  251.101967] other info that might help us debug this:
[  251.101967]
[  251.101967] Chain exists of:
  timekeeper_seq --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock#11

[  251.101967]  Possible unsafe locking scenario:
[  251.101967]
[  251.101967]        CPU0                    CPU1
[  251.101967]        ----                    ----
[  251.101967]   lock(hrtimer_bases.lock#11);
[  251.101967]                                lock(&rt_b->rt_runtime_lock);
[  251.101967]                                lock(hrtimer_bases.lock#11);
[  251.101967]   lock(timekeeper_seq);
[  251.101967]
[  251.101967]  *** DEADLOCK ***
[  251.101967]
[  251.101967] 3 locks held by kworker/10:1/4506:
[  251.101967]  #0:  (events){.+.+.+}, at: [<ffffffff81154960>] process_one_work+0x200/0x530
[  251.101967]  #1:  (hrtimer_work){+.+...}, at: [<ffffffff81154960>] process_one_work+0x200/0x530
[  251.101967]  #2:  (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70
[  251.101967]
[  251.101967] stack backtrace:
[  251.101967] CPU: 10 PID: 4506 Comm: kworker/10:1 Not tainted 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053
[  251.101967] Workqueue: events clock_was_set_work

So the best solution is to avoid calling clock_was_set_delayed() while
holding the timekeeping lock, and instead using a flag variable to
decide if we should call clock_was_set() once we've released the locks.

This works for the case here, where the do_adjtimex() was the deadlock
trigger point. Unfortuantely, in update_wall_time() we still hold
the jiffies lock, which would deadlock with the ipi triggered by
clock_was_set(), preventing us from calling it even after we drop the
timekeeping lock. So instead call clock_was_set_delayed() at that point.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: stable <stable@vger.kernel.org> #3.10+
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 11:53:33 -08:00
John Stultz
5258d3f25c timekeeping: Fix potential lost pv notification of time change
In 780427f0e1 (Indicate that clock was set in the pvclock
gtod notifier), logic was added to pass a CLOCK_WAS_SET
notification to the pvclock notifier chain.

While that patch added a action flag returned from
accumulate_nsecs_to_secs(), it only uses the returned value
in one location, and not in the logarithmic accumulation.

This means if a leap second triggered during the logarithmic
accumulation (which is most likely where it would happen),
the notification that the clock was set would not make it to
the pv notifiers.

This patch extends the logarithmic_accumulation pass down
that action flag so proper notification will occur.

This patch also changes the varialbe action -> clock_set
per Ingo's suggestion.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: <xen-devel@lists.xen.org>
Cc: stable <stable@vger.kernel.org> #3.11+
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 11:53:26 -08:00
John Stultz
f55c07607a timekeeping: Fix lost updates to tai adjustment
Since 48cdc135d4 (Implement a shadow timekeeper), we have to
call timekeeping_update() after any adjustment to the timekeeping
structure in order to make sure that any adjustments to the structure
persist.

Unfortunately, the updates to the tai offset via adjtimex do not
trigger this update, causing adjustments to the tai offset to be
made and then over-written by the previous value at the next
update_wall_time() call.

This patch resovles the issue by calling timekeeping_update()
right after setting the tai offset.

Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org> #3.10+
Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-12-23 11:47:35 -08:00
Frederic Weisbecker
e8fcaa5c54 nohz: Convert a few places to use local per cpu accesses
A few functions use remote per CPU access APIs when they
deal with local values.

Just do the right conversion to improve performance, code
readability and debug checks.

While at it, lets extend some of these function names with *_this_cpu()
suffix in order to display their purpose more clearly.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
2013-12-02 20:39:30 +01:00
Thomas Gleixner
0e576acbc1 nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=off
If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ.

If CONFIG_NO_HZ=y and the nohz functionality is disabled via the
command line option "nohz=off" or not enabled due to missing hardware
support, then tick_nohz_get_sleep_length() returns 0. That happens
because ts->sleep_length is never set in that case.

Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive.

Reported-by: Michal Hocko <mhocko@suse.cz>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-11-29 12:23:03 +01:00
Martin Schwidefsky
4be77398ac time: Fix 1ns/tick drift w/ GENERIC_TIME_VSYSCALL_OLD
Since commit 1e75fa8be9 (time: Condense timekeeper.xtime
into xtime_sec - merged in v3.6), there has been an problem
with the error accounting in the timekeeping code, such that
when truncating to nanoseconds, we round up to the next nsec,
but the balancing adjustment to the ntp_error value was dropped.

This causes 1ns per tick drift forward of the clock.

In 3.7, this logic was isolated to only GENERIC_TIME_VSYSCALL_OLD
architectures (s390, ia64, powerpc).

The fix is simply to balance the accounting and to subtract the
added nanosecond from ntp_error. This allows the internal long-term
clock steering to keep the clock accurate.

While this fix removes the regression added in 1e75fa8be9, the
ideal solution is to move away from GENERIC_TIME_VSYSCALL_OLD
and use the new VSYSCALL method, which avoids entirely the
nanosecond granular rounding, and the resulting short-term clock
adjustment oscillation needed to keep long term accurate time.

[ jstultz: Many thanks to Martin for his efforts identifying this
  	   subtle bug, and providing the fix. ]

Originally-from: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable <stable@vger.kernel.org>  #v3.6+
Link: http://lkml.kernel.org/r/1385149491-20307-1-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-11-22 21:08:11 +01:00
Andrew Morton
050ded1bba tick: Document tick_do_timer_cpu
Taken straight from a tglx email ;)

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-11-19 14:59:50 +01:00
Thomas Gleixner
d689fe222a NOHZ: Check for nohz active instead of nohz enabled
RCU and the fine grained idle time accounting functions check
tick_nohz_enabled. But that variable is merily telling that NOHZ has
been enabled in the config and not been disabled on the command line.

But it does not tell anything about nohz being active. That's what all
this should check for.

Matthew reported, that the idle accounting on his old P1 machine
showed bogus values, when he enabled NOHZ in the config and did not
disable it on the kernel command line. The reason is that his machine
uses (refined) jiffies as a clocksource which explains why the "fine"
grained accounting went into lala land, because it depends on when the
system goes and leaves idle relative to the jiffies increment.

Provide a tick_nohz_active indicator and let RCU and the accounting
code use this instead of tick_nohz_enable.

Reported-and-tested-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: john.stultz@linaro.org
Cc: mwhitehe@redhat.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311132052240.30673@ionos.tec.linutronix.de
2013-11-19 14:59:50 +01:00