linux/kernel/time, branch v2.6.32.32

clockevents: Prevent oneshot mode when broadcast device is periodic

2011-03-07T23:17:54Z

commit 3a142a0672b48a853f00af61f184c7341ac9c99d upstream. When the per cpu timer is marked CLOCK_EVT_FEAT_C3STOP, then we only can switch into oneshot mode, when the backup broadcast device supports oneshot mode as well. Otherwise we would try to switch the broadcast device into an unsupported mode unconditionally. This went unnoticed so far as the current available broadcast devices support oneshot mode. Seth unearthed this problem while debugging and working around an hpet related BIOS wreckage. Add the necessary check to tick_is_oneshot_available(). Reported-and-tested-by: Seth Forshee Signed-off-by: Thomas Gleixner LKML-Reference: Signed-off-by: Greg Kroah-Hartman

timekeeping: Fix clock_gettime vsyscall time warp

2010-08-13T20:20:13Z

commit 0696b711e4be45fa104c12329f617beb29c03f78 upstream. Since commit 0a544198 "timekeeping: Move NTP adjusted clock multiplier to struct timekeeper" the clock multiplier of vsyscall is updated with the unmodified clock multiplier of the clock source and not with the NTP adjusted multiplier of the timekeeper. This causes user space observerable time warps: new CLOCK-warp maximum: 120 nsecs, 00000025c337c537 -> 00000025c337c4bf Add a new argument "mult" to update_vsyscall() and hand in the timekeeping internal NTP adjusted multiplier. Signed-off-by: Lin Ming Cc: "Zhang Yanmin" Cc: Martin Schwidefsky Cc: Benjamin Herrenschmidt Cc: Tony Luck LKML-Reference: <1258436990.17765.83.camel@minggr.sh.intel.com> Signed-off-by: Thomas Gleixner Signed-off-by: Kurt Garloff Signed-off-by: Greg Kroah-Hartman

nohz: Reuse ktime in sub-functions of tick_check_idle.

2010-08-13T20:20:13Z

commit eed3b9cf3fe3fcc7a50238dfcab63a63914e8f42 upstream. On a system with NOHZ=y tick_check_idle calls tick_nohz_stop_idle and tick_nohz_update_jiffies. Given the right conditions (ts->idle_active and/or ts->tick_stopped) both function get a time stamp with ktime_get. The same time stamp can be reused if both function require one. On s390 this change has the additional benefit that gcc inlines the tick_nohz_stop_idle function into tick_check_idle. The number of instructions to execute tick_check_idle drops from 225 to 144 (without the ktime_get optimization it is 367 vs 215 instructions). before: 0) | tick_check_idle() { 0) | tick_nohz_stop_idle() { 0) | ktime_get() { 0) | read_tod_clock() { 0) 0.601 us | } 0) 1.765 us | } 0) 3.047 us | } 0) | ktime_get() { 0) | read_tod_clock() { 0) 0.570 us | } 0) 1.727 us | } 0) | tick_do_update_jiffies64() { 0) 0.609 us | } 0) 8.055 us | } after: 0) | tick_check_idle() { 0) | ktime_get() { 0) | read_tod_clock() { 0) 0.617 us | } 0) 1.773 us | } 0) | tick_do_update_jiffies64() { 0) 0.593 us | } 0) 4.477 us | } Signed-off-by: Martin Schwidefsky Cc: john stultz LKML-Reference: <20090929122533.206589318@de.ibm.com> Signed-off-by: Thomas Gleixner Acked-by: John Jolly Signed-off-by: Greg Kroah-Hartman

nohz: Introduce arch_needs_cpu

2010-08-13T20:20:13Z

commit 3c5d92a0cfb5103c0d5ab74d4ae6373d3af38148 upstream. Allow the architecture to request a normal jiffy tick when the system goes idle and tick_nohz_stop_sched_tick is called . On s390 the hook is used to prevent the system going fully idle if there has been an interrupt other than a clock comparator interrupt since the last wakeup. On s390 the HiperSockets response time for 1 connection ping-pong goes down from 42 to 34 microseconds. The CPU cost decreases by 27%. Signed-off-by: Martin Schwidefsky LKML-Reference: <20090929122533.402715150@de.ibm.com> Signed-off-by: Thomas Gleixner Acked-by: John Jolly Signed-off-by: Greg Kroah-Hartman

hrtimer: Tune hrtimer_interrupt hang logic

2010-04-01T22:58:14Z

commit 41d2e494937715d3150e5c75d01f0e75ae899337 upstream. The hrtimer_interrupt hang logic adjusts min_delta_ns based on the execution time of the hrtimer callbacks. This is error-prone for virtual machines, where a guest vcpu can be scheduled out during the execution of the callbacks (and the callbacks themselves can do operations that translate to blocking operations in the hypervisor), which in can lead to large min_delta_ns rendering the system unusable. Replace the current heuristics with something more reliable. Allow the interrupt code to try 3 times to catch up with the lost time. If that fails use the total time spent in the interrupt handler to defer the next timer interrupt so the system can catch up with other things which got delayed. Limit that deferment to 100ms. The retry events and the maximum time spent in the interrupt handler are recorded and exposed via /proc/timer_list Inspired by a patch from Marcelo. Reported-by: Michael Tokarev Signed-off-by: Thomas Gleixner Tested-by: Marcelo Tosatti Cc: kvm@vger.kernel.org Cc: Jeremy Fitzhardinge Signed-off-by: Greg Kroah-Hartman

timekeeping: Prevent oops when GENERIC_TIME=n

2010-04-01T22:58:06Z

commit ad6759fbf35d104dbf573cd6f4c6784ad6823f7e upstream. Aaro Koskinen reported an issue in kernel.org bugzilla #15366, where on non-GENERIC_TIME systems, accessing /sys/devices/system/clocksource/clocksource0/current_clocksource results in an oops. It seems the timekeeper/clocksource rework missed initializing the curr_clocksource value in the !GENERIC_TIME case. Thanks to Aaro for reporting and diagnosing the issue as well as testing the fix! Reported-by: Aaro Koskinen Signed-off-by: John Stultz Cc: Martin Schwidefsky LKML-Reference: <1267475683.4216.61.camel@localhost.localdomain> Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

Export the symbol of getboottime and mmonotonic_to_bootbased

2010-02-23T15:37:52Z

commit c93d89f3dbf0202bf19c07960ca8602b48c2f9a0 upstream. Export getboottime and monotonic_to_bootbased in order to let them could be used by following patch. Signed-off-by: Jason Wang Signed-off-by: Marcelo Tosatti Signed-off-by: Greg Kroah-Hartman

clocksource: fix compilation if no GENERIC_TIME

2010-02-09T12:50:54Z

commit a362c638bdf052bf424bce7645d39b101090f6ba upstream Commit a9238ce3bb0fda6e760780b702c6cbd3793087d3 broke compilation on platforms that do not implement GENERIC_TIME (e.g. iop32x): kernel/time/clocksource.c: In function 'clocksource_register': kernel/time/clocksource.c:556: error: implicit declaration of function 'clocksource_max_deferment' Provide the implementation of clocksource_max_deferment() also for such platforms. Signed-off-by: Aaro Koskinen Cc: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

nohz: Prevent clocksource wrapping during idle

2010-01-28T23:01:12Z

commit 98962465ed9e6ea99c38e0af63fe1dcb5a79dc25 upstream. The dynamic tick allows the kernel to sleep for periods longer than a single tick, but it does not limit the sleep time currently. In the worst case the kernel could sleep longer than the wrap around time of the time keeping clock source which would result in losing track of time. Prevent this by limiting it to the safe maximum sleep time of the current time keeping clock source. The value is calculated when the clock source is registered. [ tglx: simplified the code a bit and massaged the commit msg ] Signed-off-by: Jon Hunter Cc: John Stultz LKML-Reference: <1250617512-23567-2-git-send-email-jon-hunter@ti.com> Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

clockevents: Add missing include to pacify sparse

2010-01-28T23:00:24Z

commit 8e1a928a2ed7e8d5cad97c8e985294b4caedd168 upstream. Include "tick-internal.h" in order to pick up the extern function prototype for clockevents_shutdown(). This quiets the following sparse build noise: warning: symbol 'clockevents_shutdown' was not declared. Should it be static? Signed-off-by: H Hartley Sweeten LKML-Reference: Reviewed-by: Yong Zhang Cc: johnstul@us.ibm.com Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman