linux-toradex.git/kernel/hrtimer.c, branch v3.3.5

Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2011-11-28T16:43:52+00:00

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimer: Fix extra wakeups from __remove_hrtimer()
  timekeeping: add arch_offset hook to ktime_get functions
  clocksource: Avoid selecting mult values that might overflow when adjusted
  time: Improve documentation of timekeeeping_adjust()

hrtimer: Fix extra wakeups from __remove_hrtimer()

2011-11-19T11:17:37+00:00

__remove_hrtimer() attempts to reprogram the clockevent device when
the timer being removed is the next to expire. However,
__remove_hrtimer() reprograms the clockevent *before* removing the
timer from the timerqueue and thus when hrtimer_force_reprogram()
finds the next timer to expire it finds the timer we're trying to
remove.

This is especially noticeable when the system switches to NOHz mode
and the system tick is removed. The timer tick is removed from the
system but the clockevent is programmed to wakeup in another HZ
anyway.

Silence the extra wakeup by removing the timer from the timerqueue
before calling hrtimer_force_reprogram() so that we actually program
the clockevent for the next timer to expire.

This was broken by 998adc3 "hrtimers: Convert hrtimers to use
timerlist infrastructure".

Signed-off-by: Jeff Ohlstein 
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1321660030-8520-1-git-send-email-johlstei@codeaurora.org
Signed-off-by: Thomas Gleixner

kernel: Map most files to use export.h instead of module.h

2011-10-31T13:20:12+00:00

The changed files were only including linux/module.h for the
EXPORT_SYMBOL infrastructure, and nothing else.  Revector them
onto the isolated export header for faster compile times.

Nothing to see here but a whole lot of instances of:

  -#include 
  +#include 

This commit is only changing the kernel dir; next targets
will probably be mm, fs, the arch dirs, etc.

Signed-off-by: Paul Gortmaker

hrtimers: Fix typo causing erratic timers

2011-05-25T22:31:58+00:00

commit 9ec2690758a5 ("timerfd: Manage cancelable timers in timerfd")
introduced a CONFIG_HIGHRES_TIMERS (should be CONFIG_HIGH_RES_TIMERS)
typo, which caused applications depending on CLOCK_REALTIME timers to
become sluggy due to the fact that the time base of the realtime
timers was not updated when the wall clock time was set.

This causes anything from 100% CPU use for some applications to odd
delays and hickups.

Reported-bisected-and-tested-by: Anca Emanuel 
Tested-by: Linus Torvalds 
Fatfingered-by: Thomas Gleixner 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Linus Torvalds

hrtimers: Reorder clock bases

2011-05-23T11:59:54+00:00

The ordering of the clock bases is historical due to the
CLOCK_REALTIME and CLOCK_MONOTONIC constants. Now the hrtimer bases
have their own enumeration due to the gap between CLOCK_MONOTONIC and
CLOCK_BOOTTIME. So we can be more clever as most timers end up on the
CLOCK_MONOTONIC base due to the virtue of POSIX declaring that
relative CLOCK_REALTIME timers are not affected by time changes. In
desktop environments this is slowly changing as applications switch to
absolute timers, but I've observed empty CLOCK_REALTIME bases often
enough. There is no performance penalty or overhead when
CLOCK_REALTIME timers are active, but in case they are not we don't
skip over a full cache line.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Peter Zijlstra

hrtimers: Avoid touching inactive timer bases

2011-05-23T11:59:54+00:00

Instead of iterating over all possible timer bases avoid it by marking
the active bases in the cpu base.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Peter Zijlstra

timerfd: Manage cancelable timers in timerfd

2011-05-23T11:59:53+00:00

Peter is concerned about the extra scan of CLOCK_REALTIME_COS in the
timer interrupt. Yes, I did not think about it, because the solution
was so elegant. I didn't like the extra list in timerfd when it was
proposed some time ago, but with a rcu based list the list walk it's
less horrible than the original global lock, which was held over the
list iteration.

Requested-by: Peter Zijlstra 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Peter Zijlstra

timerfd: Allow timers to be cancelled when clock was set

2011-05-02T19:39:15+00:00

Some applications must be aware of clock realtime being set
backward. A simple example is a clock applet which arms a timer for
the next minute display. If clock realtime is set backward then the
applet displays a stale time for the amount of time which the clock
was set backwards. Due to that applications poll the time because we
don't have an interface.

Extend the timerfd interface by adding a flag which puts the timer
onto a different internal realtime clock. All timers on this clock are
expired whenever the clock was set.

The timerfd core records the monotonic offset when the timer is
created. When the timer is armed, then the current offset is compared
to the previous recorded offset. When it has changed, then
timerfd_settime returns -ECANCELED. When a timer is read the offset is
compared and if it changed -ECANCELED returned to user space. Periodic
timers are not rearmed in the cancelation case.

Signed-off-by: Thomas Gleixner 
Acked-by: John Stultz 
Cc: Chris Friesen 
Tested-by: Kay Sievers 
Cc: "Kirill A. Shutemov" 
Cc: Peter Zijlstra 
Cc: Davide Libenzi 
Reviewed-by: Alexander Shishkin 
Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1104271359580.3323%40ionos%3E
Signed-off-by: Thomas Gleixner

hrtimers: Prepare for cancel on clock was set timers

2011-05-02T19:37:58+00:00

Make clock_was_set() unconditional and rename hres_timers_resume to
hrtimers_resume. This is a preparatory patch for hrtimers which are
cancelled when clock realtime was set.

Signed-off-by: Thomas Gleixner

hrtimer: Make lookup table const

2011-05-02T19:37:57+00:00

Signed-off-by: Mike Frysinger 
Link: http://lkml.kernel.org/r/%3C1304364267-14489-1-git-send-email-vapier%40gentoo.org%3E
Signed-off-by: Thomas Gleixner