user/sven/linux.git/include/linux/posix-timers.h, branch v3.2

alarmtimers: Remove period from alarm structure

2011-08-10T21:55:26Z

Now that periodic alarmtimers are managed by the handler function, remove the period value from the alarm structure and let the handlers manage the interval on their own. CC: Thomas Gleixner Signed-off-by: John Stultz

posix-timers: RCU conversion

2011-05-24T10:10:51Z

Ben Nagy reported a scalability problem with KVM/QEMU that hit very hard a single spinlock (idr_lock) in posix-timers code, on its 48 core machine. Even on a 16 cpu machine (2x4x2), a single test can show 98% of cpu time used in ticket_spin_lock, from lock_timer Ref: http://www.spinics.net/lists/kvm/msg51526.html Switching to RCU is quite easy, IDR being already RCU ready. idr_lock should be locked only for an insert/delete, not a lookup. Benchmark on a 2x4x2 machine, 16 processes calling timer_gettime(). Before : real 1m18.669s user 0m1.346s sys 1m17.180s After : real 0m3.296s user 0m1.366s sys 0m1.926s Reported-by: Ben Nagy Signed-off-by: Eric Dumazet Tested-by: Ben Nagy Cc: Oleg Nesterov Cc: Avi Kivity Cc: John Stultz Cc: Richard Cochran Cc: Paul E. McKenney Cc: Andrew Morton Signed-off-by: Thomas Gleixner

timers: Posix interface for alarm-timers

2011-04-26T21:01:46Z

This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ The concept for Alarm-timers was inspired by the Android Alarm driver (by Arve Hjønnevåg) found in the Android kernel tree. See: http://android.git.kernel.org/?p=kernel/common.git;a=blob;f=drivers/rtc/alarm.c;h=1250edfbdf3302f5e4ea6194847c6ef4bb7beb1c;hb=android-2.6.36 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). CC: Arve Hjønnevåg CC: Thomas Gleixner CC: Alessandro Zummo Acked-by: Arnd Bergmann Signed-off-by: John Stultz

posix clocks: Introduce dynamic clocks

2011-02-02T14:28:20Z

This patch adds support for adding and removing posix clocks. The clock lifetime cycle is patterned after usb devices. Each clock is represented by a standard character device. In addition, the driver may optionally implement custom character device operations. The posix clock and timer system calls listed below now work with dynamic posix clocks, as well as the traditional static clocks. The following system calls are affected: - clock_adjtime (brand new syscall) - clock_gettime - clock_getres - clock_settime - timer_create - timer_delete - timer_gettime - timer_settime [ tglx: Adapted to the posix-timer cleanup. Moved clock_posix_dynamic to posix-clock.c and made all referenced functions static ] Signed-off-by: Richard Cochran Acked-by: John Stultz LKML-Reference: <20110201134420.164172635@linutronix.de> Signed-off-by: Thomas Gleixner

posix-timers: Cleanup namespace

2011-02-02T14:28:19Z

Rename register_posix_clock() to posix_timers_register_clock(). That's what the function really does. As a side effect this cleans up the posix_clock namespace for the upcoming dynamic posix_clock infrastructure. Signed-off-by: Thomas Gleixner Tested-by: Richard Cochran Cc: John Stultz LKML-Reference:

posix-timers: Add support for fd based clocks

2011-02-02T14:28:19Z

Extend the negative clockids which are currently used by posix cpu timers to encode the PID with a file descriptor based type which encodes the fd in the upper bits. Originally-from: Richard Cochran Signed-off-by: Thomas Gleixner Acked-by: John Stultz LKML-Reference: <20110201134420.062860200@linutronix.de>

posix-timers: Introduce a syscall for clock tuning.

2011-02-02T14:28:19Z

A new syscall is introduced that allows tuning of a POSIX clock. The new call, clock_adjtime, takes two parameters, the clock ID and a pointer to a struct timex. Any ADJTIMEX(2) operation may be requested via this system call, but various POSIX clocks may or may not support tuning. [ tglx: Adapted to the posix-timer cleanup series. Avoid copy_to_user in the error case ] Signed-off-by: Richard Cochran Acked-by: John Stultz LKML-Reference: <20110201134419.869804645@linutronix.de> Signed-off-by: Thomas Gleixner

posix-timers: Make posix-cpu-timers functions static

2011-02-02T14:28:17Z

All functions are accessed via clock_posix_cpu now. So make them static. Signed-off-by: Thomas Gleixner Acked-by: John Stultz Tested-by: Richard Cochran LKML-Reference: <20110201134419.389755466@linutronix.de>

posix-timers: Remove useless res field from k_clock

2011-02-02T14:28:15Z

The res member of kclock is only used by mmtimer.c, but even there it contains redundant information. Remove the field and fixup mmtimer. Signed-off-by: Thomas Gleixner Acked-by: John Stultz Tested-by: Richard Cochran LKML-Reference: <20110201134418.808714587@linutronix.de>

posix-timers: Convert clock_settime to clockid_to_kclock()

2011-02-02T14:28:14Z

Use the new kclock decoding function in clock_settime and cleanup all kclocks which use the default functions. Rename the misnomed common_clock_set() to posix_clock_realtime_set(). Signed-off-by: Thomas Gleixner Acked-by: John Stultz Tested-by: Richard Cochran LKML-Reference: <20110201134418.518851246@linutronix.de>