linux/kernel/time/timekeeping.c, branch v3.2-rc2

time: Fix stupid KERN_WARN compile issue

2011-07-20T22:42:55Z

Terribly embarassing. Don't know how I committed this, but its KERN_WARNING not KERN_WARN. This fixes the following compile error: kernel/time/timekeeping.c: In function ‘__timekeeping_inject_sleeptime’: kernel/time/timekeeping.c:608: error: ‘KERN_WARN’ undeclared (first use in this function) kernel/time/timekeeping.c:608: error: (Each undeclared identifier is reported only once kernel/time/timekeeping.c:608: error: for each function it appears in.) kernel/time/timekeeping.c:608: error: expected ‘)’ before string constant make[2]: *** [kernel/time/timekeeping.o] Error 1 Reported-by: Ingo Molnar Signed-off-by: John Stultz

time: Avoid accumulating time drift in suspend/resume

2011-06-21T23:55:37Z

Because the read_persistent_clock interface is usually backed by only a second granular interface, each time we read from the persistent clock for suspend/resume, we introduce a half second (on average) of error. In order to avoid this error accumulating as the system is suspended over and over, this patch measures the time delta between the persistent clock and the system CLOCK_REALTIME. If the delta is less then 2 seconds from the last suspend, we compensate by using the previous time delta (keeping it close). If it is larger then 2 seconds, we assume the clock was set or has been changed, so we do no correction and update the delta. Note: If NTP is running, ths could seem to "fight" with the NTP corrected time, where as if the system time was off by 1 second, and NTP slewed the value in, a suspend/resume cycle could undo this correction, by trying to restore the previous offset from the persistent clock. However, without this patch, since each read could cause almost a full second worth of error, its possible to get almost 2 seconds of error just from the suspend/resume cycle alone, so this about equal to any offset added by the compensation. Further on systems that suspend/resume frequently, this should keep time closer then NTP could compensate for if the errors were allowed to accumulate. Credits to Arve Hjønnevåg for suggesting this solution. CC: Arve Hjønnevåg CC: Thomas Gleixner Signed-off-by: John Stultz

time: Catch invalid timespec sleep values in __timekeeping_inject_sleeptime

2011-06-21T23:55:36Z

Arve suggested making sure we catch possible negative sleep time intervals that could be passed into timekeeping_inject_sleeptime. CC: Arve Hjønnevåg CC: Thomas Gleixner Signed-off-by: John Stultz

timerfd: Allow timers to be cancelled when clock was set

2011-05-02T19:39:15Z

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

2011-05-02T19:37:58Z

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

time: Add timekeeping_inject_sleeptime

2011-04-26T21:01:41Z

Some platforms cannot implement read_persistent_clock, as their RTC devices are only accessible when interrupts are enabled. This keeps them from being used by the timekeeping code on resume to measure the time in suspend. The RTC layer tries to work around this, by calling do_settimeofday on resume after irqs are reenabled to set the time properly. However, this only corrects CLOCK_REALTIME, and does not properly adjust the sleep time value. This causes btime in /proc/stat to be incorrect as well as making the new CLOCK_BOTTTIME inaccurate. This patch resolves the issue by introducing a new timekeeping hook to allow the RTC layer to inject the sleep time on resume. The code also checks to make sure that read_persistent_clock is nonfunctional before setting the sleep time, so that should the RTC's HCTOSYS option be configured in on a system that does support read_persistent_clock we will not increase the total_sleep_time twice. CC: Arve Hjønnevåg CC: Thomas Gleixner Acked-by: Arnd Bergmann Signed-off-by: John Stultz

timekeeping: Use syscore_ops instead of sysdev class and sysdev

2011-03-23T21:16:04Z

The timekeeping subsystem uses a sysdev class and a sysdev for executing timekeeping_suspend() after interrupts have been turned off on the boot CPU (during system suspend) and for executing timekeeping_resume() before turning on interrupts on the boot CPU (during system resume). However, since both of these functions ignore their arguments, the entire mechanism may be replaced with a struct syscore_ops object which is simpler. Signed-off-by: Rafael J. Wysocki Reviewed-by: Thomas Gleixner

time: Extend get_xtime_and_monotonic_offset() to also return sleep

2011-02-21T20:53:07Z

Extend get_xtime_and_monotonic_offset to get_xtime_and_monotonic_and_sleep_offset(). CC: Jamie Lokier CC: Thomas Gleixner CC: Alexander Shishkin CC: Arve Hjønnevåg Signed-off-by: John Stultz

time: Introduce get_monotonic_boottime and ktime_get_boottime

2011-02-21T20:53:05Z

This adds new functions that return the monotonic time since boot (in other words, CLOCK_MONOTONIC + suspend time). CC: Jamie Lokier CC: Thomas Gleixner CC: Alexander Shishkin CC: Arve Hjønnevåg Signed-off-by: John Stultz

time: Introduce timekeeping_inject_offset

2011-02-02T14:28:18Z

This adds a kernel-internal timekeeping interface to add or subtract a fixed amount from CLOCK_REALTIME. This makes it so kernel users or interfaces trying to do so do not have to read the time, then add an offset and then call settimeofday(), which adds some extra error in comparision to just simply adding the offset in the kernel timekeeping core. Signed-off-by: John Stultz Signed-off-by: Richard Cochran LKML-Reference: <20110201134419.584311693@linutronix.de> Signed-off-by: Thomas Gleixner