kernel/linux.git/include/linux/clocksource.h, branch linux-2.6.28.y

clocksource: introduce CLOCK_MONOTONIC_RAW

2008-08-21T07:50:24+00:00

In talking with Josip Loncaric, and his work on clock synchronization (see btime.sf.net), he mentioned that for really close synchronization, it is useful to have access to "hardware time", that is a notion of time that is not in any way adjusted by the clock slewing done to keep close time sync. Part of the issue is if we are using the kernel's ntp adjusted representation of time in order to measure how we should correct time, we can run into what Paul McKenney aptly described as "Painting a road using the lines we're painting as the guide". I had been thinking of a similar problem, and was trying to come up with a way to give users access to a purely hardware based time representation that avoided users having to know the underlying frequency and mask values needed to deal with the wide variety of possible underlying hardware counters. My solution is to introduce CLOCK_MONOTONIC_RAW. This exposes a nanosecond based time value, that increments starting at bootup and has no frequency adjustments made to it what so ever. The time is accessed from userspace via the posix_clock_gettime() syscall, passing CLOCK_MONOTONIC_RAW as the clock_id. Signed-off-by: John Stultz Signed-off-by: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar

clocksource: keep track of original clocksource frequency

2008-08-21T07:50:23+00:00

The clocksource frequency is represented by clocksource->mult/2^(clocksource->shift). Currently, when NTP makes adjustments to the clock frequency, they are made directly to the mult value. This has the drawback that once changed, we cannot know what the orignal mult value was, or how much adjustment has been applied. This property causes problems in calculating proper ntp intervals when switching back and forth between clocksources. This patch separates the current mult value into a mult and mult_orig pair. The mult_orig value stays constant, while the ntp clocksource adjustments are done only to the mult value. This allows for correct ntp interval calculation and additionally lays the groundwork for a new notion of time, what I'm calling the monotonic-raw time, which is introduced in a following patch. Signed-off-by: John Stultz Signed-off-by: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar

ntp: handle leap second via timer

2008-05-01T15:03:59+00:00

Remove the leap second handling from second_overflow(), which doesn't have to check for it every second anymore. With CONFIG_NO_HZ this also makes sure the leap second is handled close to the full second. Additionally this makes it possible to abort a leap second properly by resetting the STA_INS/STA_DEL status bits. Signed-off-by: Roman Zippel Cc: john stultz Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kgdb: clocksource watchdog

2008-04-17T18:05:38+00:00

In order to not trip the clocksource watchdog, kgdb must touch the clocksource watchdog on the return to normal system run state. Signed-off-by: Jason Wessel Signed-off-by: Ingo Molnar

clocksource: add unregister function to disable unusable clocksources

2008-01-30T12:30:02+00:00

On x86 the PIT might become an unusable clocksource. Add an unregister function to provide a possibilty to remove the PIT from the list of available clock sources. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

clocksource: make CLOCKSOURCE_MASK bullet-proof

2008-01-30T12:30:01+00:00

Signed-off-by: Atsushi Nemoto Cc: john stultz Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner

Fix discrepancy between VDSO based gettimeofday() and sys_gettimeofday().

2007-10-18T21:37:20+00:00

On platforms that copy sys_tz into the vdso (currently only x86_64, soon to include powerpc), it is possible for the vdso to get out of sync if a user calls (admittedly unusual) settimeofday(NULL, ptr). This patch adds a hook for architectures that set CONFIG_GENERIC_TIME_VSYSCALL to ensure when sys_tz is updated they can also updatee their copy in the vdso. Signed-off-by: Tony Breeds Cc: Andi Kleen Cc: Tony Luck Acked-by: John Stultz Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[IA64] Convert to generic timekeeping/clocksource

2007-07-20T18:22:30+00:00

This is a merge of Peter Keilty's initial patch (which was revived by Bob Picco) for this with Hidetoshi Seto's fixes and scaling improvements. Acked-by: Bob Picco Signed-off-by: Tony Luck

clocksource: fix resume logic

2007-05-09T19:30:56+00:00

We need to make sure that the clocksources are resumed, when timekeeping is resumed. The current resume logic does not guarantee this. Add a resume function pointer to the clocksource struct, so clocksource drivers which need to reinitialize the clocksource can provide a resume function. Add a resume function, which calls the maybe available clocksource resume functions and resets the watchdog function, so a stable TSC can be used accross suspend/resume. Signed-off-by: Thomas Gleixner Cc: john stultz Cc: Andi Kleen Cc: Ingo Molnar Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

time: SMP friendly alignment of struct clocksource

2007-05-08T18:15:06+00:00

struct clocksource is a critical data structure. Most of its fields are read only, some of them are heavily modified at each timer interrupt. It makes sense to separate those fields and make sure they all share one cache line, or at least the minimum for machines with small cache lines. [akpm@linux-foundation.org: build fix] Signed-off-by: Eric Dumazet Acked-by: John Stultz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds