kernel/linux.git/include/linux/hrtimer.h, branch linux-2.6.34.y

timekeeping: Provide hrtimer update function

2012-08-17T19:35:49+00:00

commit f6c06abfb3972ad4914cef57d8348fcb2932bc3b upstream. To finally fix the infamous leap second issue and other race windows caused by functions which change the offsets between the various time bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a function which atomically gets the current monotonic time and updates the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic overhead. The previous patch which provides ktime_t offsets allows us to make this function almost as cheap as ktime_get() which is going to be replaced in hrtimer_interrupt(). Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Prarit Bhargava Signed-off-by: John Stultz Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com Signed-off-by: Thomas Gleixner Cc: Prarit Bhargava Cc: Thomas Gleixner Cc: Linux Kernel Signed-off-by: John Stultz Signed-off-by: Paul Gortmaker

hrtimer: Provide clock_was_set_delayed()

2012-08-17T19:35:47+00:00

commit f55a6faa384304c89cfef162768e88374d3312cb upstream. clock_was_set() cannot be called from hard interrupt context because it calls on_each_cpu(). For fixing the widely reported leap seconds issue it is necessary to call it from hard interrupt context, i.e. the timer tick code, which does the timekeeping updates. Provide a new function which denotes it in the hrtimer cpu base structure of the cpu on which it is called and raise the hrtimer softirq. We then execute the clock_was_set() notificiation from softirq context in run_hrtimer_softirq(). The hrtimer softirq is rarely used, so polling the flag there is not a performance issue. [ tglx: Made it depend on CONFIG_HIGH_RES_TIMERS. We really should get rid of all this ifdeffery ASAP ] Signed-off-by: John Stultz Reported-by: Jan Engelhardt Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Prarit Bhargava Link: http://lkml.kernel.org/r/1341960205-56738-2-git-send-email-johnstul@us.ibm.com Signed-off-by: Thomas Gleixner Cc: Prarit Bhargava Cc: Thomas Gleixner Cc: Linux Kernel Signed-off-by: John Stultz Signed-off-by: Paul Gortmaker

hrtimers: Convert to raw_spinlocks

2009-12-14T22:55:34+00:00

Convert locks which cannot be sleeping locks in preempt-rt to raw_spinlocks. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: Ingo Molnar

hrtimer: move timer stats helper functions to hrtimer.c

2009-12-10T12:08:11+00:00

There is no reason to make timer_stats_hrtimer_set_start_info and friends visible to the rest of the kernel. So move all of them to hrtimer.c. Also make timer_stats_hrtimer_set_start_info a static inline function so it gets inlined and we avoid another function call. Based on a patch by Thomas Gleixner. Signed-off-by: Heiko Carstens LKML-Reference: <20091210095629.GC4144@osiris.boeblingen.de.ibm.com> Signed-off-by: Thomas Gleixner

hrtimer: Tune hrtimer_interrupt hang logic

2009-12-10T12:08:11+00:00

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

hrtimer: Fix /proc/timer_list regression

2009-11-20T10:25:48+00:00

commit 507e1231 (timer stats: Optimize by adding quick check to avoid function calls) introduced a regression in /proc/timer_list. /proc/timer_list shows now #0: , tick_sched_timer, S:01, <(null)>, /-1 instead of #0: , tick_sched_timer, S:01, hrtimer_start, swapper/0 Revert the hrtimer quick check for now. The optimization needs more thought, but this is neither 2.6.32-rc7 nor stable material. [ tglx: - Removed unrelated changes from the original patch - Prevent unneccesary call to timer_stats_update_stats - massaged the changelog ] Signed-off-by: Feng Tang LKML-Reference: Cc: Heiko Carstens Cc: stable@kernel.org Signed-off-by: Andrew Morton Signed-off-by: Thomas Gleixner

Merge branch 'linus' into timers/core

2009-08-14T13:59:30+00:00

Reason: Martin's timekeeping cleanup series depends on both timers/core and mainline changes. Signed-off-by: Thomas Gleixner

hrtimer: Remove cb_entry from struct hrtimer

2009-07-22T15:12:32+00:00

It's unused, remove it. Signed-off-by: Peter Zijlstra Signed-off-by: Thomas Gleixner LKML-Reference:

timer stats: fix quick check optimization

2009-07-10T17:33:00+00:00

git commit 507e1231 "timer stats: Optimize by adding quick check to avoid function calls" added one wrong check so that one unnecessary function call isn't elimated. time_stats_account_hrtimer() checks if timer->start_pid isn't initialized in order to find out if timer_stats_update_stats() should be called. However start_pid is initialized with -1 instead of 0, so that the function call always happens. Check timer->start_site like in timer_stats_account_timer() to fix this. Signed-off-by: Heiko Carstens Signed-off-by: Thomas Gleixner

timer stats: Optimize by adding quick check to avoid function calls

2009-06-24T09:15:09+00:00

When the kernel is configured with CONFIG_TIMER_STATS but timer stats are runtime disabled we still get calls to __timer_stats_timer_set_start_info which initializes some fields in the corresponding struct timer_list. So add some quick checks in the the timer stats setup functions to avoid function calls to __timer_stats_timer_set_start_info when timer stats are disabled. In an artificial workload that does nothing but playing ping pong with a single tcp packet via loopback this decreases cpu consumption by 1 - 1.5%. This is part of a modified function trace output on SLES11: perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer Signed-off-by: Heiko Carstens Cc: Andrew Morton Cc: Martin Schwidefsky Cc: Mustafa Mesanovic Cc: Arjan van de Ven LKML-Reference: <20090623153811.GA4641@osiris.boeblingen.de.ibm.com> Signed-off-by: Ingo Molnar