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* tick-sched: Check tick_nohz_enabled in tick_nohz_switch_to_nohz()Viresh Kumar2014-04-151-1/+1
| | | | | | | | | | | | | | | | | | Since commit d689fe222 (NOHZ: Check for nohz active instead of nohz enabled) the tick_nohz_switch_to_nohz() function returns because it checks for the tick_nohz_active flag. This can't be set, because the function itself sets it. Undo the change in tick_nohz_switch_to_nohz(). Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: linaro-kernel@lists.linaro.org Cc: fweisbec@gmail.com Cc: Arvind.Chauhan@arm.com Cc: linaro-networking@linaro.org Cc: <stable@vger.kernel.org> # 3.13+ Link: http://lkml.kernel.org/r/40939c05f2d65d781b92b20302b02243d0654224.1397537987.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* tick-sched: Don't call update_wall_time() when delta is lesser than tick_periodViresh Kumar2014-04-151-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | In tick_do_update_jiffies64() we are processing ticks only if delta is greater than tick_period. This is what we are supposed to do here and it broke a bit with this patch: commit 47a1b796 (tick/timekeeping: Call update_wall_time outside the jiffies lock) With above patch, we might end up calling update_wall_time() even if delta is found to be smaller that tick_period. Fix this by returning when the delta is less than tick period. [ tglx: Made it a 3 liner and massaged changelog ] Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: linaro-kernel@lists.linaro.org Cc: fweisbec@gmail.com Cc: Arvind.Chauhan@arm.com Cc: linaro-networking@linaro.org Cc: John Stultz <john.stultz@linaro.org> Cc: <stable@vger.kernel.org> # v3.14+ Link: http://lkml.kernel.org/r/80afb18a494b0bd9710975bcc4de134ae323c74f.1397537987.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* tick-common: Fix wrong check in tick_check_replacement()Viresh Kumar2014-04-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | tick_check_replacement() returns if a replacement of clock_event_device is possible or not. It does this as the first check: if (tick_check_percpu(curdev, newdev, smp_processor_id())) return false; Thats wrong. tick_check_percpu() returns true when the device is useable. Check for false instead. [ tglx: Massaged changelog ] Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: <stable@vger.kernel.org> # v3.11+ Cc: linaro-kernel@lists.linaro.org Cc: fweisbec@gmail.com Cc: Arvind.Chauhan@arm.com Cc: linaro-networking@linaro.org Link: http://lkml.kernel.org/r/486a02efe0246635aaba786e24b42d316438bf3b.1397537987.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* kernel: use macros from compiler.h instead of __attribute__((...))Gideon Israel Dsouza2014-04-071-2/+3
| | | | | | | | | | | | | To increase compiler portability there is <linux/compiler.h> which provides convenience macros for various gcc constructs. Eg: __weak for __attribute__((weak)). I've replaced all instances of gcc attributes with the right macro in the kernel subsystem. Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'timers-core-for-linus' of ↵Linus Torvalds2014-04-019-36/+236
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer changes from Thomas Gleixner: "This assorted collection provides: - A new timer based timer broadcast feature for systems which do not provide a global accessible timer device. That allows those systems to put CPUs into deep idle states where the per cpu timer device stops. - A few NOHZ_FULL related improvements to the timer wheel - The usual updates to timer devices found in ARM SoCs - Small improvements and updates all over the place" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits) tick: Remove code duplication in tick_handle_periodic() tick: Fix spelling mistake in tick_handle_periodic() x86: hpet: Use proper destructor for delayed work workqueue: Provide destroy_delayed_work_on_stack() clocksource: CMT, MTU2, TMU and STI should depend on GENERIC_CLOCKEVENTS timer: Remove code redundancy while calling get_nohz_timer_target() hrtimer: Rearrange comments in the order struct members are declared timer: Use variable head instead of &work_list in __run_timers() clocksource: exynos_mct: silence a static checker warning arm: zynq: Add support for cpufreq arm: zynq: Don't use arm_global_timer with cpufreq clocksource/cadence_ttc: Overhaul clocksource frequency adjustment clocksource/cadence_ttc: Call clockevents_update_freq() with IRQs enabled clocksource: Add Kconfig entries for CMT, MTU2, TMU and STI sh: Remove Kconfig entries for TMU, CMT and MTU2 ARM: shmobile: Remove CMT, TMU and STI Kconfig entries clocksource: armada-370-xp: Use atomic access for shared registers clocksource: orion: Use atomic access for shared registers clocksource: timer-keystone: Delete unnecessary variable clocksource: timer-keystone: introduce clocksource driver for Keystone ...
| * tick: Remove code duplication in tick_handle_periodic()Viresh Kumar2014-03-261-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | tick_handle_periodic() is calling ktime_add() at two places, first before the infinite loop and then at the end of infinite loop. We can rearrange code a bit to fix code duplication here. It looks quite simple and shouldn't break anything, I guess :) Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: linaro-kernel@lists.linaro.org Cc: fweisbec@gmail.com Link: http://lkml.kernel.org/r/be3481e8f3f71df694a4b43623254fc93ca51b59.1395735873.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * tick: Fix spelling mistake in tick_handle_periodic()Viresh Kumar2014-03-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | One of the comments in tick_handle_periodic() had 'when' instead of 'which' (My guess :)). Fix it. Also fix spelling mistake in 'Possible'. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: linaro-kernel@lists.linaro.org Cc: skarafotis@gmail.com Link: http://lkml.kernel.org/r/2b29ca4230c163e44179941d7c7a16c1474385c2.1395743878.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * Merge branch 'fortglx/3.15/time' of ↵Thomas Gleixner2014-03-101-0/+2
| |\ | | | | | | | | | | | | | | | | | | | | | | | | git://git.linaro.org/people/john.stultz/linux into timers/core - support CLOCK_BOOTTIME clock in timerfd - Add missing header file Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| | * kernel: Include appropriate header file in time/timekeeping_debug.cRashika Kheria2014-03-021-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Include appropriate header file kernel/time/timekeeping_internal.h in kernel/time/timekeeping_debug.c because it has prototype declaration of function defined in kernel/time/timekeeping_debug.c. This eliminates the following warning in kernel/time/timekeeping_debug.c: kernel/time/timekeeping_debug.c:68:6: warning: no previous prototype for ‘tk_debug_account_sleep_time’ [-Wmissing-prototypes] Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
| * | nohz: ensure users are aware boot CPU is not NO_HZ_FULLPaul Gortmaker2014-02-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This bit of information is in the Kconfig help text: "Note the boot CPU will still be kept outside the range to handle the timekeeping duty." However neither the variable NO_HZ_FULL_ALL, or the prompt convey this important detail, so lets add it to the prompt to make it more explicitly obvious to the average user. Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1391711781-7466-1-git-send-email-paul.gortmaker@windriver.com Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
| * | tick: Fixup more fallout from hrtimer broadcast modePreeti U Murthy2014-02-092-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The hrtimer mode of broadcast is supported only when GENERIC_CLOCKEVENTS_BROADCAST and TICK_ONESHOT config options are enabled. Hence compile in the functions for hrtimer mode of broadcast only when these options are selected. Also fix max_delta_ticks value for the pseudo clock device. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/52F719EE.9010304@linux.vnet.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | time: Fixup fallout from recent clockevent/tick changesThomas Gleixner2014-02-071-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make the stub function static inline instead of static and move the clockevents related function into the proper ifdeffed section. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Soren Brinkmann <soren.brinkmann@xilinx.com> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
| * | tick: Introduce hrtimer based broadcastPreeti U Murthy2014-02-073-4/+158
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On some architectures, in certain CPU deep idle states the local timers stop. An external clock device is used to wakeup these CPUs. The kernel support for the wakeup of these CPUs is provided by the tick broadcast framework by using the external clock device as the wakeup source. However not all implementations of architectures provide such an external clock device. This patch includes support in the broadcast framework to handle the wakeup of the CPUs in deep idle states on such systems by queuing a hrtimer on one of the CPUs, which is meant to handle the wakeup of CPUs in deep idle states. This patchset introduces a pseudo clock device which can be registered by the archs as tick_broadcast_device in the absence of a real external clock device. Once registered, the broadcast framework will work as is for these architectures as long as the archs take care of the BROADCAST_ENTER notification failing for one of the CPUs. This CPU is made the stand by CPU to handle wakeup of the CPUs in deep idle and it *must not enter deep idle states*. The CPU with the earliest wakeup is chosen to be this CPU. Hence this way the stand by CPU dynamically moves around and so does the hrtimer which is queued to trigger at the next earliest wakeup time. This is consistent with the case where an external clock device is present. The smp affinity of this clock device is set to the CPU with the earliest wakeup. This patchset handles the hotplug of the stand by CPU as well by moving the hrtimer on to the CPU handling the CPU_DEAD notification. Originally-from: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: deepthi@linux.vnet.ibm.com Cc: paulmck@linux.vnet.ibm.com Cc: fweisbec@gmail.com Cc: paulus@samba.org Cc: srivatsa.bhat@linux.vnet.ibm.com Cc: svaidy@linux.vnet.ibm.com Cc: peterz@infradead.org Cc: benh@kernel.crashing.org Cc: rafael.j.wysocki@intel.com Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20140207080632.17187.80532.stgit@preeti.in.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | time: Change the return type of clockevents_notify() to integerPreeti U Murthy2014-02-073-8/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The broadcast framework can potentially be made use of by archs which do not have an external clock device as well. Then, it is required that one of the CPUs need to handle the broadcasting of wakeup IPIs to the CPUs in deep idle. As a result its local timers should remain functional all the time. For such a CPU, the BROADCAST_ENTER notification has to fail indicating that its clock device cannot be shutdown. To make way for this support, change the return type of tick_broadcast_oneshot_control() and hence clockevents_notify() to indicate such scenarios. Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: deepthi@linux.vnet.ibm.com Cc: paulmck@linux.vnet.ibm.com Cc: fweisbec@gmail.com Cc: paulus@samba.org Cc: srivatsa.bhat@linux.vnet.ibm.com Cc: svaidy@linux.vnet.ibm.com Cc: peterz@infradead.org Cc: benh@kernel.crashing.org Cc: rafael.j.wysocki@intel.com Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20140207080606.17187.78306.stgit@preeti.in.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | clockevents: Adjust timer interval when frequency changesSoren Brinkmann2014-02-071-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | clockevent devices in periodic mode are not updated when the frequency of the device changes. Issue a dev->set_mode() callback which forces the device to reevaluate the timer settings. Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> Cc: linux-arm-kernel@lists.infradead.org Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Michal Simek <michal.simek@xilinx.com> Link: http://lkml.kernel.org/r/1391466877-28908-3-git-send-email-soren.brinkmann@xilinx.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | clockevents: Serialize calls to clockevents_update_freq() in the coreThomas Gleixner2014-02-073-13/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We can identify the broadcast device in the core and serialize all callers including interrupts on a different CPU against the update. Also, disabling interrupts is moved into the core allowing callers to leave interrutps enabled when calling clockevents_update_freq(). Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com> Cc: linux-arm-kernel@lists.infradead.org Cc: Soeren Brinkmann <soren.brinkmann@xilinx.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Michal Simek <michal.simek@xilinx.com> Link: http://lkml.kernel.org/r/1391466877-28908-2-git-send-email-soren.brinkmann@xilinx.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | timekeeping: Move clock sync work to power efficient workqueueShaibal Dutta2014-02-071-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For better use of CPU idle time, allow the scheduler to select the CPU on which the CMOS clock sync work would be scheduled. This improves idle residency time and conserver power. This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected. Signed-off-by: Shaibal Dutta <shaibal.dutta@broadcom.com> [zoran.markovic@linaro.org: Added commit message. Aligned code.] Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org> Cc: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/1391195904-12497-1-git-send-email-zoran.markovic@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | time: Revert to calling clock_was_set_delayed() while in irq contextJohn Stultz2014-03-281-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In commit 47a1b796306356f35 ("tick/timekeeping: Call update_wall_time outside the jiffies lock"), we moved to calling clock_was_set() due to the fact that we were no longer holding the timekeeping or jiffies lock. However, there is still the problem that clock_was_set() triggers an IPI, which cannot be done from the timer's hard irq context, and will generate WARN_ON warnings. Apparently in my earlier testing, I'm guessing I didn't bump the dmesg log level, so I somehow missed the WARN_ONs. Thus we need to revert back to calling clock_was_set_delayed(). Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1395963049-11923-1-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | sched_clock: Prevent callers from seeing half-updated dataStephen Boyd2014-02-191-17/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The generic sched_clock registration function was previously done lockless, due to the fact that it was expected to be called only once. However, now there are systems that may register multiple sched_clock sources, for which the lack of locking has casued problems: If two sched_clock sources are registered we may end up in a situation where a call to sched_clock() may be accessing the epoch cycle count for the old counter and the cycle count for the new counter. This can lead to confusing results where sched_clock() values jump and then are reset to 0 (due to the way the registration function forces the epoch_ns to be 0). Fix this by reorganizing the registration function to hold the seqlock for as short a time as possible while we update the clock_data structure for a new counter. We also put any accumulated time into epoch_ns instead of resetting the time to 0 so that the clock doesn't reset after each successful registration. [jstultz: Added extra context to the commit message] Reported-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Josh Cartwright <joshc@codeaurora.org> Link: http://lkml.kernel.org/r/1392662736-7803-2-git-send-email-john.stultz@linaro.org Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | tick: Clear broadcast pending bit when switching to oneshotThomas Gleixner2014-02-131-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | AMD systems which use the C1E workaround in the amd_e400_idle routine trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU. The reason is that the idle routine of those AMD systems switches the cpu into forced broadcast mode early on before the newly brought up CPU can switch over to high resolution / NOHZ mode. The timer related CPU1 bringup looks like this: clockevent_register_device(local_apic); tick_setup(local_apic); ... idle() tick_broadcast_on_off(FORCE); tick_broadcast_oneshot_control(ENTER) cpumask_set(cpu, broadcast_oneshot_mask); halt(); Now the broadcast interrupt on CPU0 sets CPU1 in the broadcast_pending_mask and wakes CPU1. So CPU1 continues: local_apic_timer_interrupt() tick_handle_periodic(); softirq() tick_init_highres(); cpumask_clr(cpu, broadcast_oneshot_mask); tick_broadcast_oneshot_control(ENTER) WARN_ON(cpumask_test(cpu, broadcast_pending_mask); So while we remove CPU1 from the broadcast_oneshot_mask when we switch over to highres mode, we do not clear the pending bit, which then triggers the warning when we go back to idle. The reason why this is only visible on C1E affected AMD systems is that the other machines enter the deep sleep states via acpi_idle/intel_idle and exit the broadcast mode before executing the remote triggered local_apic_timer_interrupt. So the pending bit is already cleared when the switch over to highres mode is clearing the oneshot mask. The solution is simple: Clear the pending bit together with the mask bit when we switch over to highres mode. Stanislaw came up independently with the same patch by enforcing the C1E workaround and debugging the fallout. I picked mine, because mine has a changelog :) Reported-by: poma <pomidorabelisima@gmail.com> Debugged-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Olaf Hering <olaf@aepfle.de> Cc: Dave Jones <davej@redhat.com> Cc: Justin M. Forbes <jforbes@redhat.com> Cc: Josh Boyer <jwboyer@redhat.com> Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1402111434180.21991@ionos.tec.linutronix.de Cc: stable@vger.kernel.org # 3.10+ Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | time: Fix overflow when HZ is smaller than 60Mikulas Patocka2014-02-061-0/+6
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When compiling for the IA-64 ski emulator, HZ is set to 32 because the emulation is slow and we don't want to waste too many cycles processing timers. Alpha also has an option to set HZ to 32. This causes integer underflow in kernel/time/jiffies.c: kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow] .mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */ ^ This patch reduces the JIFFIES_SHIFT value to avoid the overflow. Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com Cc: stable@vger.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | Merge branch 'timers/core' of ↵Ingo Molnar2014-01-251-13/+14
|\ \ | |/ |/| | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/urgent Pull dynticks cleanups from Frederic Weisbecker. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * nohz_full: fix code style issue of tick_nohz_full_stop_tickAlex Shi2014-01-151-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Code usually starts with 'tab' instead of 7 'space' in kernel Signed-off-by: Alex Shi <alex.shi@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alex Shi <alex.shi@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Kevin Hilman <khilman@linaro.org> Link: http://lkml.kernel.org/r/1386074112-30754-2-git-send-email-alex.shi@linaro.org Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
| * nohz: Get timekeeping max deferment outside jiffies_lockFrederic Weisbecker2014-01-151-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We don't need to fetch the timekeeping max deferment under the jiffies_lock seqlock. If the clocksource is updated concurrently while we stop the tick, stop machine is called and the tick will be reevaluated again along with uptodate jiffies and its related values. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alex Shi <alex.shi@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Kevin Hilman <khilman@linaro.org> Link: http://lkml.kernel.org/r/1387320692-28460-9-git-send-email-fweisbec@gmail.com Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
| * tick: Rename tick_check_idle() to tick_irq_enter()Frederic Weisbecker2014-01-151-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This makes the code more symetric against the existing tick functions called on irq exit: tick_irq_exit() and tick_nohz_irq_exit(). These function are also symetric as they mirror each other's action: we start to account idle time on irq exit and we stop this accounting on irq entry. Also the tick is stopped on irq exit and timekeeping catches up with the tickless time elapsed until we reach irq entry. This rename was suggested by Peter Zijlstra a long while ago but it got forgotten in the mass. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alex Shi <alex.shi@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Kevin Hilman <khilman@linaro.org> Link: http://lkml.kernel.org/r/1387320692-28460-2-git-send-email-fweisbec@gmail.com Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* | Merge branch 'timers-core-for-linus' of ↵Linus Torvalds2014-01-205-55/+50
|\ \ | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer changes from Ingo Molnar: - ARM clocksource/clockevent improvements and fixes - generic timekeeping updates: TAI fixes/improvements, cleanups - Posix cpu timer cleanups and improvements - dynticks updates: full dynticks bugfixes, optimizations and cleanups * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits) clocksource: Timer-sun5i: Switch to sched_clock_register() timekeeping: Remove comment that's mostly out of date rtc-cmos: Add an alarm disable quirk timekeeper: fix comment typo for tk_setup_internals() timekeeping: Fix missing timekeeping_update in suspend path timekeeping: Fix CLOCK_TAI timer/nanosleep delays tick/timekeeping: Call update_wall_time outside the jiffies lock timekeeping: Avoid possible deadlock from clock_was_set_delayed timekeeping: Fix potential lost pv notification of time change timekeeping: Fix lost updates to tai adjustment clocksource: sh_cmt: Add clk_prepare/unprepare support clocksource: bcm_kona_timer: Remove unused bcm_timer_ids clocksource: vt8500: Remove deprecated IRQF_DISABLED clocksource: tegra: Remove deprecated IRQF_DISABLED clocksource: misc drivers: Remove deprecated IRQF_DISABLED clocksource: sh_mtu2: Remove unnecessary platform_set_drvdata() clocksource: sh_tmu: Remove unnecessary platform_set_drvdata() clocksource: armada-370-xp: Enable timer divider only when needed clocksource: clksrc-of: Warn if no clock sources are found clocksource: orion: Switch to sched_clock_register() ...
| * Merge branch 'fortglx/3.14/time' of ↵Ingo Molnar2014-01-124-27/+29
| |\ | | | | | | | | | | | | | | | | | | | | | git://git.linaro.org/people/john.stultz/linux into timers/core Pull timekeeping updates from John Stultz. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| | * timekeeping: Remove comment that's mostly out of dateJohn Stultz2013-12-231-10/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Prior to 92bb1fcf57a0c2e45f7e67fbf0a8ed475a749236 (Only do nanosecond rounding on GENERIC_TIME_VSYSCALL_OLD systems), the comment here was accuate, but now we can mostly avoid the extra rounding which causes the unlikey to be actually likely here. So remove the out of date comment. Signed-off-by: John Stultz <john.stultz@linaro.org>
| | * timekeeper: fix comment typo for tk_setup_internals()Yijing Wang2013-12-231-1/+2
| | | | | | | | | | | | | | | | | | | | | Fix trivial comment typo for tk_setup_internals(). Signed-off-by: Yijing Wang <wangyijing@huawei.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
| | * timekeeping: Fix missing timekeeping_update in suspend pathJohn Stultz2013-12-231-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since 48cdc135d4840 (Implement a shadow timekeeper), we have to call timekeeping_update() after any adjustment to the timekeeping structure in order to make sure that any adjustments to the structure persist. In the timekeeping suspend path, we udpate the timekeeper structure, so we should be sure to update the shadow-timekeeper before releasing the timekeeping locks. Currently this isn't done. In most cases, the next time related code to run would be timekeeping_resume, which does update the shadow-timekeeper, but in an abundence of caution, this patch adds the call to timekeeping_update() in the suspend path. Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable <stable@vger.kernel.org> #3.10+ Signed-off-by: John Stultz <john.stultz@linaro.org>
| | * timekeeping: Fix CLOCK_TAI timer/nanosleep delaysJohn Stultz2013-12-231-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A think-o in the calculation of the monotonic -> tai time offset results in CLOCK_TAI timers and nanosleeps to expire late (the latency is ~2x the tai offset). Fix this by adding the tai offset from the realtime offset instead of subtracting. Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable <stable@vger.kernel.org> #3.10+ Signed-off-by: John Stultz <john.stultz@linaro.org>
| | * tick/timekeeping: Call update_wall_time outside the jiffies lockJohn Stultz2013-12-234-15/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the xtime lock was split into the timekeeping lock and the jiffies lock, we no longer need to call update_wall_time() while holding the jiffies lock. Thus, this patch splits update_wall_time() out from do_timer(). This allows us to get away from calling clock_was_set_delayed() in update_wall_time() and instead use the standard clock_was_set() call that previously would deadlock, as it causes the jiffies lock to be acquired. Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
| | * timekeeping: Avoid possible deadlock from clock_was_set_delayedJohn Stultz2013-12-231-2/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As part of normal operaions, the hrtimer subsystem frequently calls into the timekeeping code, creating a locking order of hrtimer locks -> timekeeping locks clock_was_set_delayed() was suppoed to allow us to avoid deadlocks between the timekeeping the hrtimer subsystem, so that we could notify the hrtimer subsytem the time had changed while holding the timekeeping locks. This was done by scheduling delayed work that would run later once we were out of the timekeeing code. But unfortunately the lock chains are complex enoguh that in scheduling delayed work, we end up eventually trying to grab an hrtimer lock. Sasha Levin noticed this in testing when the new seqlock lockdep enablement triggered the following (somewhat abrieviated) message: [ 251.100221] ====================================================== [ 251.100221] [ INFO: possible circular locking dependency detected ] [ 251.100221] 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053 Not tainted [ 251.101967] ------------------------------------------------------- [ 251.101967] kworker/10:1/4506 is trying to acquire lock: [ 251.101967] (timekeeper_seq){----..}, at: [<ffffffff81160e96>] retrigger_next_event+0x56/0x70 [ 251.101967] [ 251.101967] but task is already holding lock: [ 251.101967] (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70 [ 251.101967] [ 251.101967] which lock already depends on the new lock. [ 251.101967] [ 251.101967] [ 251.101967] the existing dependency chain (in reverse order) is: [ 251.101967] -> #5 (hrtimer_bases.lock#11){-.-...}: [snipped] -> #4 (&rt_b->rt_runtime_lock){-.-...}: [snipped] -> #3 (&rq->lock){-.-.-.}: [snipped] -> #2 (&p->pi_lock){-.-.-.}: [snipped] -> #1 (&(&pool->lock)->rlock){-.-...}: [ 251.101967] [<ffffffff81194803>] validate_chain+0x6c3/0x7b0 [ 251.101967] [<ffffffff81194d9d>] __lock_acquire+0x4ad/0x580 [ 251.101967] [<ffffffff81194ff2>] lock_acquire+0x182/0x1d0 [ 251.101967] [<ffffffff84398500>] _raw_spin_lock+0x40/0x80 [ 251.101967] [<ffffffff81153e69>] __queue_work+0x1a9/0x3f0 [ 251.101967] [<ffffffff81154168>] queue_work_on+0x98/0x120 [ 251.101967] [<ffffffff81161351>] clock_was_set_delayed+0x21/0x30 [ 251.101967] [<ffffffff811c4bd1>] do_adjtimex+0x111/0x160 [ 251.101967] [<ffffffff811e2711>] compat_sys_adjtimex+0x41/0x70 [ 251.101967] [<ffffffff843a4b49>] ia32_sysret+0x0/0x5 [ 251.101967] -> #0 (timekeeper_seq){----..}: [snipped] [ 251.101967] other info that might help us debug this: [ 251.101967] [ 251.101967] Chain exists of: timekeeper_seq --> &rt_b->rt_runtime_lock --> hrtimer_bases.lock#11 [ 251.101967] Possible unsafe locking scenario: [ 251.101967] [ 251.101967] CPU0 CPU1 [ 251.101967] ---- ---- [ 251.101967] lock(hrtimer_bases.lock#11); [ 251.101967] lock(&rt_b->rt_runtime_lock); [ 251.101967] lock(hrtimer_bases.lock#11); [ 251.101967] lock(timekeeper_seq); [ 251.101967] [ 251.101967] *** DEADLOCK *** [ 251.101967] [ 251.101967] 3 locks held by kworker/10:1/4506: [ 251.101967] #0: (events){.+.+.+}, at: [<ffffffff81154960>] process_one_work+0x200/0x530 [ 251.101967] #1: (hrtimer_work){+.+...}, at: [<ffffffff81154960>] process_one_work+0x200/0x530 [ 251.101967] #2: (hrtimer_bases.lock#11){-.-...}, at: [<ffffffff81160e7c>] retrigger_next_event+0x3c/0x70 [ 251.101967] [ 251.101967] stack backtrace: [ 251.101967] CPU: 10 PID: 4506 Comm: kworker/10:1 Not tainted 3.13.0-rc2-next-20131206-sasha-00005-g8be2375-dirty #4053 [ 251.101967] Workqueue: events clock_was_set_work So the best solution is to avoid calling clock_was_set_delayed() while holding the timekeeping lock, and instead using a flag variable to decide if we should call clock_was_set() once we've released the locks. This works for the case here, where the do_adjtimex() was the deadlock trigger point. Unfortuantely, in update_wall_time() we still hold the jiffies lock, which would deadlock with the ipi triggered by clock_was_set(), preventing us from calling it even after we drop the timekeeping lock. So instead call clock_was_set_delayed() at that point. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: stable <stable@vger.kernel.org> #3.10+ Reported-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
| | * timekeeping: Fix potential lost pv notification of time changeJohn Stultz2013-12-231-9/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In 780427f0e11 (Indicate that clock was set in the pvclock gtod notifier), logic was added to pass a CLOCK_WAS_SET notification to the pvclock notifier chain. While that patch added a action flag returned from accumulate_nsecs_to_secs(), it only uses the returned value in one location, and not in the logarithmic accumulation. This means if a leap second triggered during the logarithmic accumulation (which is most likely where it would happen), the notification that the clock was set would not make it to the pv notifiers. This patch extends the logarithmic_accumulation pass down that action flag so proper notification will occur. This patch also changes the varialbe action -> clock_set per Ingo's suggestion. Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: <xen-devel@lists.xen.org> Cc: stable <stable@vger.kernel.org> #3.11+ Signed-off-by: John Stultz <john.stultz@linaro.org>
| | * timekeeping: Fix lost updates to tai adjustmentJohn Stultz2013-12-231-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since 48cdc135d4840 (Implement a shadow timekeeper), we have to call timekeeping_update() after any adjustment to the timekeeping structure in order to make sure that any adjustments to the structure persist. Unfortunately, the updates to the tai offset via adjtimex do not trigger this update, causing adjustments to the tai offset to be made and then over-written by the previous value at the next update_wall_time() call. This patch resovles the issue by calling timekeeping_update() right after setting the tai offset. Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable <stable@vger.kernel.org> #3.10+ Signed-off-by: John Stultz <john.stultz@linaro.org>
| * | Merge branch 'linus' into timers/coreIngo Molnar2014-01-123-14/+28
| |\ \ | | |/ | |/| | | | | | | | | | Pick up the latest fixes and refresh the branch. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | nohz: Convert a few places to use local per cpu accessesFrederic Weisbecker2013-12-023-28/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A few functions use remote per CPU access APIs when they deal with local values. Just do the right conversion to improve performance, code readability and debug checks. While at it, lets extend some of these function names with *_this_cpu() suffix in order to display their purpose more clearly. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org>
* | | Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2014-01-201-1/+1
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler changes from Ingo Molnar: - Add the initial implementation of SCHED_DEADLINE support: a real-time scheduling policy where tasks that meet their deadlines and periodically execute their instances in less than their runtime quota see real-time scheduling and won't miss any of their deadlines. Tasks that go over their quota get delayed (Available to privileged users for now) - Clean up and fix preempt_enable_no_resched() abuse all around the tree - Do sched_clock() performance optimizations on x86 and elsewhere - Fix and improve auto-NUMA balancing - Fix and clean up the idle loop - Apply various cleanups and fixes * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) sched: Fix __sched_setscheduler() nice test sched: Move SCHED_RESET_ON_FORK into attr::sched_flags sched: Fix up attr::sched_priority warning sched: Fix up scheduler syscall LTP fails sched: Preserve the nice level over sched_setscheduler() and sched_setparam() calls sched/core: Fix htmldocs warnings sched/deadline: No need to check p if dl_se is valid sched/deadline: Remove unused variables sched/deadline: Fix sparse static warnings m68k: Fix build warning in mac_via.h sched, thermal: Clean up preempt_enable_no_resched() abuse sched, net: Fixup busy_loop_us_clock() sched, net: Clean up preempt_enable_no_resched() abuse sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding sched/preempt, locking: Rework local_bh_{dis,en}able() sched/clock, x86: Avoid a runtime condition in native_sched_clock() sched/clock: Fix up clear_sched_clock_stable() sched/clock, x86: Use a static_key for sched_clock_stable sched/clock: Remove local_irq_disable() from the clocks sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs ...
| * | | sched/clock, x86: Use a static_key for sched_clock_stablePeter Zijlstra2014-01-131-1/+1
| | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to avoid the runtime condition and variable load turn sched_clock_stable into a static_key. Also provide a shorter implementation of local_clock() and cpu_clock(int) when sched_clock_stable==1. MAINLINE PRE POST sched_clock_stable: 1 1 1 (cold) sched_clock: 329841 221876 215295 (cold) local_clock: 301773 234692 220773 (warm) sched_clock: 38375 25602 25659 (warm) local_clock: 100371 33265 27242 (warm) rdtsc: 27340 24214 24208 sched_clock_stable: 0 0 0 (cold) sched_clock: 382634 235941 237019 (cold) local_clock: 396890 297017 294819 (warm) sched_clock: 38194 25233 25609 (warm) local_clock: 143452 71234 71232 (warm) rdtsc: 27345 24245 24243 Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-eummbdechzz37mwmpags1gjr@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | sched_clock: Disable seqlock lockdep usage in sched_clock()John Stultz2014-01-121-3/+3
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Unfortunately the seqlock lockdep enablement can't be used in sched_clock(), since the lockdep infrastructure eventually calls into sched_clock(), which causes a deadlock. Thus, this patch changes all generic sched_clock() usage to use the raw_* methods. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Reported-by: Krzysztof Hałasa <khalasa@piap.pl> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1388704274-5278-2-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | nohz: Fix another inconsistency between CONFIG_NO_HZ=n and nohz=offThomas Gleixner2013-11-291-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If CONFIG_NO_HZ=n tick_nohz_get_sleep_length() returns NSEC_PER_SEC/HZ. If CONFIG_NO_HZ=y and the nohz functionality is disabled via the command line option "nohz=off" or not enabled due to missing hardware support, then tick_nohz_get_sleep_length() returns 0. That happens because ts->sleep_length is never set in that case. Set it to NSEC_PER_SEC/HZ when the NOHZ mode is inactive. Reported-by: Michal Hocko <mhocko@suse.cz> Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | time: Fix 1ns/tick drift w/ GENERIC_TIME_VSYSCALL_OLDMartin Schwidefsky2013-11-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit 1e75fa8be9f (time: Condense timekeeper.xtime into xtime_sec - merged in v3.6), there has been an problem with the error accounting in the timekeeping code, such that when truncating to nanoseconds, we round up to the next nsec, but the balancing adjustment to the ntp_error value was dropped. This causes 1ns per tick drift forward of the clock. In 3.7, this logic was isolated to only GENERIC_TIME_VSYSCALL_OLD architectures (s390, ia64, powerpc). The fix is simply to balance the accounting and to subtract the added nanosecond from ntp_error. This allows the internal long-term clock steering to keep the clock accurate. While this fix removes the regression added in 1e75fa8be9f, the ideal solution is to move away from GENERIC_TIME_VSYSCALL_OLD and use the new VSYSCALL method, which avoids entirely the nanosecond granular rounding, and the resulting short-term clock adjustment oscillation needed to keep long term accurate time. [ jstultz: Many thanks to Martin for his efforts identifying this subtle bug, and providing the fix. ] Originally-from: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Paul Turner <pjt@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable <stable@vger.kernel.org> #v3.6+ Link: http://lkml.kernel.org/r/1385149491-20307-1-git-send-email-john.stultz@linaro.org Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | tick: Document tick_do_timer_cpuAndrew Morton2013-11-191-0/+15
| | | | | | | | | | | | | | Taken straight from a tglx email ;) Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | NOHZ: Check for nohz active instead of nohz enabledThomas Gleixner2013-11-191-12/+9
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | RCU and the fine grained idle time accounting functions check tick_nohz_enabled. But that variable is merily telling that NOHZ has been enabled in the config and not been disabled on the command line. But it does not tell anything about nohz being active. That's what all this should check for. Matthew reported, that the idle accounting on his old P1 machine showed bogus values, when he enabled NOHZ in the config and did not disable it on the kernel command line. The reason is that his machine uses (refined) jiffies as a clocksource which explains why the "fine" grained accounting went into lala land, because it depends on when the system goes and leaves idle relative to the jiffies increment. Provide a tick_nohz_active indicator and let RCU and the accounting code use this instead of tick_nohz_enable. Reported-and-tested-by: Matthew Whitehead <tedheadster@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: john.stultz@linaro.org Cc: mwhitehe@redhat.com Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311132052240.30673@ionos.tec.linutronix.de
* Merge branch 'timers-core-for-linus' of ↵Linus Torvalds2013-11-1210-84/+107
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer changes from Ingo Molnar: "Main changes in this cycle were: - Updated full dynticks support. - Event stream support for architected (ARM) timers. - ARM clocksource driver updates. - Move arm64 to using the generic sched_clock framework & resulting cleanup in the generic sched_clock code. - Misc fixes and cleanups" * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits) x86/time: Honor ACPI FADT flag indicating absence of a CMOS RTC clocksource: sun4i: remove IRQF_DISABLED clocksource: sun4i: Report the minimum tick that we can program clocksource: sun4i: Select CLKSRC_MMIO clocksource: Provide timekeeping for efm32 SoCs clocksource: em_sti: convert to clk_prepare/unprepare time: Fix signedness bug in sysfs_get_uname() and its callers timekeeping: Fix some trivial typos in comments alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't exist clocksource: arch_timer: Do not register arch_sys_counter twice timer stats: Add a 'Collection: active/inactive' line to timer usage statistics sched_clock: Remove sched_clock_func() hook arch_timer: Move to generic sched_clock framework clocksource: tcb_clksrc: Remove IRQF_DISABLED clocksource: tcb_clksrc: Improve driver robustness clocksource: tcb_clksrc: Replace clk_enable/disable with clk_prepare_enable/disable_unprepare clocksource: arm_arch_timer: Use clocksource for suspend timekeeping clocksource: dw_apb_timer_of: Mark a few more functions as __init clocksource: Put nodes passed to CLOCKSOURCE_OF_DECLARE callbacks centrally arm: zynq: Enable arm_global_timer ...
| * time: Fix signedness bug in sysfs_get_uname() and its callersPatrick Palka2013-10-183-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sysfs_get_uname() is erroneously declared as returning size_t even though it may return a negative value, specifically -EINVAL. Its callers then check whether its return value is less than zero and indeed that is never the case for size_t. This patch changes sysfs_get_uname() to return ssize_t and makes sure its callers use ssize_t accordingly. Signed-off-by: Patrick Palka <patrick@parcs.ath.cx> [jstultz: Didn't apply cleanly, as a similar partial fix was also applied so had to resolve the collisions] Signed-off-by: John Stultz <john.stultz@linaro.org>
| * timekeeping: Fix some trivial typos in commentsXie XiuQi2013-10-181-1/+2
| | | | | | | | | | | | | | | | Fix some typos in timekeeping comments. Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com> [jstultz: Commit message tweaks] Signed-off-by: John Stultz <john.stultz@linaro.org>
| * alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't existKOSAKI Motohiro2013-10-181-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide on ARM. (http://bugs.ruby-lang.org/issues/9008) Because of, commit 1c6b39ad3f (alarmtimers: Return -ENOTSUPP if no RTC device is present) intruduced to return ENOTSUPP when clock_get{time,res} can't find a RTC device. However this is incorrect. First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the closest userland equivlents). Second, Posix and Linux man pages agree that clock_gettime and clock_getres should return EINVAL if clk_id argument is invalid. While the arugment that the clockid is valid, but just not supported on this hardware could be made, this is just a technicality that doesn't help userspace applicaitons, and only complicates error handling. Thus, this patch changes the code to use EINVAL. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: stable <stable@vger.kernel.org> #3.0 and up Reported-by: Vit Ondruch <v.ondruch@tiscali.cz> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> [jstultz: Tweaks to commit message to include full rational] Signed-off-by: John Stultz <john.stultz@linaro.org>
| * timer stats: Add a 'Collection: active/inactive' line to timer usage statisticsDong Zhu2013-10-101-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We can enable/disable timer statistics collection via: echo [1|0] > /proc/timers_stats and it would be nice if apps had the ability to check what the current collection status is. This patch adds a 'Collection: active/inactive' line to display the current timer collection status. Also bump up the timer stats version to v0.3. Signed-off-by: Dong Zhu <bluezhudong@gmail.com> Cc: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/20131010075618.GH2139@zhudong.nay.redhat.com [ Improved the changelog and the code. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * Merge branch 'fortglx/3.13/time' of ↵Ingo Molnar2013-10-102-10/+3
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.linaro.org/people/jstultz/linux into timers/core Pull more timekeeping items for v3.13 from John Stultz: * Small cleanup in the clocksource code. * Fix for rtc-pl031 to let it work with alarmtimers. * Move arm64 to using the generic sched_clock framework & resulting cleanup in the generic sched_clock code. Signed-off-by: Ingo Molnar <mingo@kernel.org>
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