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2009-06-20Merge branch 'timers-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: NOHZ: Properly feed cpufreq ondemand governor
2009-05-27NOHZ: Properly feed cpufreq ondemand governorEero Nurkkala
A call from irq_exit() may occasionally pause the timing info for cpufreq ondemand governor. This results in the cpufreq ondemand governor to fail to calculate the system load properly. Thus, relocate the checks for this particular case to keep the governor always functional. Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com> Reported-by: Tero Kristo <tero.kristo@nokia.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-05-13timers: Identifying the existing pinned timersArun R Bharadwaj
* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]: The following pinned hrtimers have been identified and marked: 1)sched_rt_period_timer 2)tick_sched_timer 3)stack_trace_timer_fn [ tglx: fixup the hrtimer pinned mode ] Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-01-15time-sched.c: tick_nohz_update_jiffies should be staticJaswinder Singh Rajput
Impact: cleanup, reduce kernel size a bit, avoid sparse warning Fixes sparse warning: kernel/time/tick-sched.c:137:6: warning: symbol 'tick_nohz_update_jiffies' was not declared. Should it be static? Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-03Merge branch 'cputime' of git://git390.osdl.marist.edu/pub/scm/linux-2.6Linus Torvalds
* 'cputime' of git://git390.osdl.marist.edu/pub/scm/linux-2.6: [PATCH] fast vdso implementation for CLOCK_THREAD_CPUTIME_ID [PATCH] improve idle cputime accounting [PATCH] improve precision of idle time detection. [PATCH] improve precision of process accounting. [PATCH] idle cputime accounting [PATCH] fix scaled & unscaled cputime accounting
2009-01-02Merge branch 'cpus4096-for-linus-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'cpus4096-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (66 commits) x86: export vector_used_by_percpu_irq x86: use logical apicid in x2apic_cluster's x2apic_cpu_mask_to_apicid_and() sched: nominate preferred wakeup cpu, fix x86: fix lguest used_vectors breakage, -v2 x86: fix warning in arch/x86/kernel/io_apic.c sched: fix warning in kernel/sched.c sched: move test_sd_parent() to an SMP section of sched.h sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0 sched: activate active load balancing in new idle cpus sched: bias task wakeups to preferred semi-idle packages sched: nominate preferred wakeup cpu sched: favour lower logical cpu number for sched_mc balance sched: framework for sched_mc/smt_power_savings=N sched: convert BALANCE_FOR_xx_POWER to inline functions x86: use possible_cpus=NUM to extend the possible cpus allowed x86: fix cpu_mask_to_apicid_and to include cpu_online_mask x86: update io_apic.c to the new cpumask code x86: Introduce topology_core_cpumask()/topology_thread_cpumask() x86: xen: use smp_call_function_many() x86: use work_on_cpu in x86/kernel/cpu/mcheck/mce_amd_64.c ... Fixed up trivial conflict in kernel/time/tick-sched.c manually
2008-12-31[PATCH] idle cputime accountingMartin Schwidefsky
The cpu time spent by the idle process actually doing something is currently accounted as idle time. This is plain wrong, the architectures that support VIRT_CPU_ACCOUNTING=y can do better: distinguish between the time spent doing nothing and the time spent by idle doing work. The first is accounted with account_idle_time and the second with account_system_time. The architectures that use the account_xxx_time interface directly and not the account_xxx_ticks interface now need to do the check for the idle process in their arch code. In particular to improve the system vs true idle time accounting the arch code needs to measure the true idle time instead of just testing for the idle process. To improve the tick based accounting as well we would need an architecture primitive that can tell us if the pt_regs of the interrupted context points to the magic instruction that halts the cpu. In addition idle time is no more added to the stime of the idle process. This field now contains the system time of the idle process as it should be. On systems without VIRT_CPU_ACCOUNTING this will always be zero as every tick that occurs while idle is running will be accounted as idle time. This patch contains the necessary common code changes to be able to distinguish idle system time and true idle time. The architectures with support for VIRT_CPU_ACCOUNTING need some changes to exploit this. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-31[PATCH] fix scaled & unscaled cputime accountingMartin Schwidefsky
The utimescaled / stimescaled fields in the task structure and the global cpustat should be set on all architectures. On s390 the calls to account_user_time_scaled and account_system_time_scaled never have been added. In addition system time that is accounted as guest time to the user time of a process is accounted to the scaled system time instead of the scaled user time. To fix the bugs and to prevent future forgetfulness this patch merges account_system_time_scaled into account_system_time and account_user_time_scaled into account_user_time. Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Michael Neuling <mikey@neuling.org> Acked-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-12-25Merge branches 'timers/clocksource', 'timers/hpet', 'timers/hrtimers', ↵Ingo Molnar
'timers/nohz', 'timers/ntp', 'timers/posixtimers' and 'timers/rtc' into timers/core
2008-12-12nohz: suppress needless timer reprogrammingWoodruff, Richard
In my device I get many interrupts from a high speed USB device in a very short period of time. The system spends a lot of time reprogramming the hardware timer which is in a slower timing domain as compared to the CPU. This results in the CPU spending a huge amount of time waiting for the timer posting to be done. All of this reprogramming is useless as the wake up time has not changed. As measured using ETM trace this drops my reprogramming penalty from almost 60% CPU load down to 15% during high interrupt rate. I can send traces to show this. Suppress setting of duplicate timer event when timer already stopped. Timer programming can be very costly and can result in long cpu stall/wait times. [akpm@linux-foundation.org: coding-style fixes] [tglx@linutronix.de: move the check to the right place and avoid raising the softirq for nothing] Signed-off-by: Richard Woodruff <r-woodruff2@ti.com> Cc: johnstul@us.ibm.com Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-12-12nohz: no softirq pending warnings for offline cpusHeiko Carstens
Impact: remove false positive warning After a cpu was taken down during cpu hotplug (read: disabled for interrupts) it still might have pending softirqs. However take_cpu_down makes sure that the idle task will run next instead of ksoftirqd on the taken down cpu. The idle task will call tick_nohz_stop_sched_tick which might warn about pending softirqs just before the cpu kills itself completely. However the pending softirqs on the dead cpu aren't a problem because they will be moved to an online cpu during CPU_DEAD handling. So make sure we warn only for online cpus. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-25hrtimer: removing all ur callback modesPeter Zijlstra
Impact: cleanup, move all hrtimer processing into hardirq context This is an attempt at removing some of the hrtimer complexity by reducing the number of callback modes to 1. This means that all hrtimer callback functions will be ran from HARD-irq context. I went through all the 30 odd hrtimer callback functions in the kernel and saw only one that I'm not quite sure of, which is the one in net/can/bcm.c - hence I'm CC-ing the folks responsible for that code. Furthermore, the hrtimer core now calls callbacks directly with IRQs disabled in case you try to enqueue an expired timer. If this timer is a periodic timer (which should use hrtimer_forward() to advance its time) then it might be possible to end up in an inf. recursive loop due to the fact that hrtimer_forward() doesn't round up to the next timer granularity, and therefore keeps on calling the callback - obviously this needs a fix. Aside from that, this seems to compile and actually boot on my dual core test box - although I'm sure there are some bugs in, me not hitting any makes me certain :-) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-24sched: convert nohz_cpu_mask to cpumask_var_t.Rusty Russell
Impact: (future) size reduction for large NR_CPUS. Dynamically allocating cpumasks (when CONFIG_CPUMASK_OFFSTACK) saves space for small nr_cpu_ids but big CONFIG_NR_CPUS. cpumask_var_t is just a struct cpumask for !CONFIG_CPUMASK_OFFSTACK. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-10nohz: disable tick_nohz_kick_tick() for nowThomas Gleixner
Impact: nohz powersavings and wakeup regression commit fb02fbc14d17837b4b7b02dbb36142c16a7bf208 (NOHZ: restart tick device from irq_enter()) causes a serious wakeup regression. While the patch is correct it does not take into account that spurious wakeups happen on x86. A fix for this issue is available, but we just revert to the .27 behaviour and let long running softirqs screw themself. Disable it for now. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-22Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2Thomas Gleixner
Conflicts: kernel/time/tick-sched.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-21NOHZ: fix thinko in the timer restart code pathThomas Gleixner
commit fb02fbc14d17837b4b7b02dbb36142c16a7bf208 (NOHZ: restart tick device from irq_enter()) solves the problem of stale jiffies when long running softirqs happen in a long idle sleep period, but it has a major thinko in it: When the interrupt which came in _is_ the timer interrupt which should expire ts->sched_timer then we cancel and rearm the timer _before_ it gets expired in hrtimer_interrupt() to the next period. That means the call back function is not called. This game can go on for ever :( Prevent this by making sure to only rearm the timer when the expiry time is more than one tick_period away. Otherwise keep it running as it is either already expired or will expiry at the right point to update jiffies. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Venkatesch Pallipadi <venkatesh.pallipadi@intel.com>
2008-10-17Merge commit 'linus/master' into merge-linusArjan van de Ven
Conflicts: arch/x86/kvm/i8254.c
2008-10-17NOHZ: restart tick device from irq_enter()Thomas Gleixner
We did not restart the tick device from irq_enter() to avoid double reprogramming and extra events in the return immediate to idle case. But long lasting softirqs can lead to a situation where jiffies become stale: idle() tick stopped (reprogrammed to next pending timer) halt() interrupt jiffies updated from irq_enter() interrupt handler softirq function 1 runs 20ms softirq function 2 arms a 10ms timer with a stale jiffies value jiffies updated from irq_exit() timer wheel has now an already expired timer (the one added in function 2) timer fires and timer softirq runs This was discovered when debugging a timer problem which happend only when the ath5k driver is active. The debugging proved that there is a softirq function running for more than 20ms, which is a bug by itself. To solve this we restart the tick timer right from irq_enter(), but do not go through the other functions which are necessary to return from idle when need_resched() is set. Reported-by: Elias Oltmanns <eo@nebensachen.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Elias Oltmanns <eo@nebensachen.de>
2008-10-17NOHZ: split tick_nohz_restart_sched_tick()Thomas Gleixner
Split out the clock event device reprogramming. Preparatory patch. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-17NOHZ: unify the nohz function calls in irq_enter()Thomas Gleixner
We have two separate nohz function calls in irq_enter() for no good reason. Just call a single NOHZ function from irq_enter() and call the bits in the tick code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-15Merge branches 'core/softlockup', 'core/softirq', 'core/resources', ↵Ingo Molnar
'core/printk' and 'core/misc' into core-v28-for-linus
2008-10-09[CPUFREQ][5/6] cpufreq: Changes to get_cpu_idle_time_us(), used by ondemand ↵venkatesh.pallipadi@intel.com
governor export get_cpu_idle_time_us() for it to be used in ondemand governor. Last update time can be current time when the CPU is currently non-idle, accounting for the busy time since last idle. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Dave Jones <davej@redhat.com>
2008-09-29hrtimer: prevent migration of per CPU hrtimersThomas Gleixner
Impact: per CPU hrtimers can be migrated from a dead CPU The hrtimer code has no knowledge about per CPU timers, but we need to prevent the migration of such timers and warn when such a timer is active at migration time. Explicitely mark the timers as per CPU and use a more understandable mode descriptor for the interrupts safe unlocked callback mode, which is used by hrtimer_sleeper and the scheduler code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-23clockevents: prevent stale tick_next_period for onlining CPUsThomas Gleixner
Impact: possible hang on CPU onlining in timer one shot mode. The tick_next_period variable is only used during boot on nohz/highres enabled systems, but for CPU onlining it needs to be maintained when the per cpu clock events device operates in one shot mode. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-23clockevents: prevent cpu online to interfere with nohzThomas Gleixner
Impact: rare hang which can be triggered on CPU online. tick_do_timer_cpu keeps track of the CPU which updates jiffies via do_timer. The value -1 is used to signal, that currently no CPU is doing this. There are two cases, where the variable can have this state: boot: necessary for systems where the boot cpu id can be != 0 nohz long idle sleep: When the CPU which did the jiffies update last goes into a long idle sleep it drops the update jiffies duty so another CPU which is not idle can pick it up and keep jiffies going. Using the same value for both situations is wrong, as the CPU online code can see the -1 state when the timer of the newly onlined CPU is setup. The setup for a newly onlined CPU goes through periodic mode and can pick up the do_timer duty without being aware of the nohz / highres mode of the already running system. Use two separate states and make them constants to avoid magic numbers confusion. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-09-05hrtimer: convert kernel/* to the new hrtimer apisArjan van de Ven
In order to be able to do range hrtimers we need to use accessor functions to the "expire" member of the hrtimer struct. This patch converts kernel/* to these accessors. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
2008-09-05sched_clock: fix NOHZ interactionPeter Zijlstra
If HLT stops the TSC, we'll fail to account idle time, thereby inflating the actual process times. Fix this by re-calibrating the clock against GTOD when leaving nohz mode. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Avi Kivity <avi@qumranet.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-21nohz: fix wrong event handler after online an offlined cpuMiao Xie
On the tickless system(CONFIG_NO_HZ=y and CONFIG_HIGH_RES_TIMERS=n), after I made an offlined cpu online, I found this cpu's event handler was tick_handle_periodic, not tick_nohz_handler. After debuging, I found this bug was caused by the wrong tick mode. the tick mode is not changed to NOHZ_MODE_INACTIVE when the cpu is offline. This patch fixes this bug. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-11printk: robustify printkPeter Zijlstra
Avoid deadlocks against rq->lock and xtime_lock by deferring the klogd wakeup by polling from the timer tick. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-31sched clock: revert various sched_clock() changesIngo Molnar
Found an interactivity problem on a quad core test-system - simple CPU loops would occasionally delay the system un an unacceptable way. After much debugging with Peter Zijlstra it turned out that the problem is caused by the string of sched_clock() changes - they caused the CPU clock to jump backwards a bit - which confuses the scheduler arithmetics. (which is unsigned for performance reasons) So revert: # c300ba2: sched_clock: and multiplier for TSC to gtod drift # c0c8773: sched_clock: only update deltas with local reads. # af52a90: sched_clock: stop maximum check on NO HZ # f7cce27: sched_clock: widen the max and min time This solves the interactivity problems. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Mike Galbraith <efault@gmx.de>
2008-07-24Merge branch 'timers-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: nohz: adjust tick_nohz_stop_sched_tick() call of s390 as well nohz: prevent tick stop outside of the idle loop
2008-07-18Merge branch 'linus' into timers/nohzIngo Molnar
2008-07-18nohz: prevent tick stop outside of the idle loopThomas Gleixner
Jack Ren and Eric Miao tracked down the following long standing problem in the NOHZ code: scheduler switch to idle task enable interrupts Window starts here ----> interrupt happens (does not set NEED_RESCHED) irq_exit() stops the tick ----> interrupt happens (does set NEED_RESCHED) return from schedule() cpu_idle(): preempt_disable(); Window ends here The interrupts can happen at any point inside the race window. The first interrupt stops the tick, the second one causes the scheduler to rerun and switch away from idle again and we end up with the tick disabled. The fact that it needs two interrupts where the first one does not set NEED_RESCHED and the second one does made the bug obscure and extremly hard to reproduce and analyse. Kudos to Jack and Eric. Solution: Limit the NOHZ functionality to the idle loop to make sure that we can not run into such a situation ever again. cpu_idle() { preempt_disable(); while(1) { tick_nohz_stop_sched_tick(1); <- tell NOHZ code that we are in the idle loop while (!need_resched()) halt(); tick_nohz_restart_sched_tick(); <- disables NOHZ mode preempt_enable_no_resched(); schedule(); preempt_disable(); } } In hindsight we should have done this forever, but ... /me grabs a large brown paperbag. Debugged-by: Jack Ren <jack.ren@marvell.com>, Debugged-by: eric miao <eric.y.miao@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-07-15Merge branch 'linus' into core/softlockupIngo Molnar
Conflicts: kernel/softlockup.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-15Merge branch 'timers/for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timers/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86: add PCI ID for 6300ESB force hpet x86: add another PCI ID for ICH6 force-hpet kernel-paramaters: document pmtmr= command line option acpi_pm clccksource: fix printk format warning nohz: don't stop idle tick if softirqs are pending. pmtmr: allow command line override of ioport nohz: reduce jiffies polling overhead hrtimer: Remove unused variables in ktime_divns() hrtimer: remove warning in hres_timers_resume posix-timers: print RT watchdog message
2008-07-11sched_clock: stop maximum check on NO HZSteven Rostedt
Working with ftrace I would get large jumps of 11 millisecs or more with the clock tracer. This killed the latencing timings of ftrace and also caused the irqoff self tests to fail. What was happening is with NO_HZ the idle would stop the jiffy counter and before the jiffy counter was updated the sched_clock would have a bad delta jiffies to compare with the gtod with the maximum. The jiffies would stop and the last sched_tick would record the last gtod. On wakeup, the sched clock update would compare the gtod + delta jiffies (which would be zero) and compare it to the TSC. The TSC would have correctly (with a stable TSC) moved forward several jiffies. But because the jiffies has not been updated yet the clock would be prevented from moving forward because it would appear that the TSC jumped too far ahead. The clock would then virtually stop, until the jiffies are updated. Then the next sched clock update would see that the clock was very much behind since the delta jiffies is now correct. This would then jump the clock forward by several jiffies. This caused ftrace to report several milliseconds of interrupts off latency at every resume from NO_HZ idle. This patch adds hooks into the nohz code to disable the checking of the maximum clock update when nohz is in effect. It resumes the max check when nohz has updated the jiffies again. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-11nohz: don't stop idle tick if softirqs are pending.Heiko Carstens
In case a cpu goes idle but softirqs are pending only an error message is printed to the console. It may take a very long time until the pending softirqs will finally be executed. Worst case would be a hanging system. With this patch the timer tick just continues and the softirqs will be executed after the next interrupt. Still a delay but better than a hanging system. Currently we have at least two device drivers on s390 which under certain circumstances schedule a tasklet from process context. This is a reason why we can end up with pending softirqs when going idle. Fixing these drivers seems to be non-trivial. However there is no question that the drivers should be fixed. This patch shouldn't be considered as a bug fix. It just is intended to keep a system running even if device drivers are buggy. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Jan Glauber <jan.glauber@de.ibm.com> Cc: Stefan Weinhuber <wein@de.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-30nohz: reduce jiffies polling overheadIngo Molnar
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-30softlockup: fix false positives on nohz if CPU is 100% idle for more than 60 ↵Ingo Molnar
seconds Fix (probably theoretical only) rq->clock update bug: in tick_nohz_update_jiffies() [which is called on all irq entry on all cpus where the irq entry hits an idle cpu] we call touch_softlockup_watchdog() before we update jiffies. That works fine most of the time when idle timeouts are within 60 seconds. But when an idle timeout is beyond 60 seconds, jiffies is updated with a jump of more than 60 seconds, which causes a jump in cpu-clock of more than 60 seconds, triggering a false positive. Reported-by: David Miller <davem@davemloft.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-25softlockup: fix NOHZ wakeupIngo Molnar
David Miller reported: |---------------> the following commit: | commit 27ec4407790d075c325e1f4da0a19c56953cce23 | Author: Ingo Molnar <mingo@elte.hu> | Date: Thu Feb 28 21:00:21 2008 +0100 | | sched: make cpu_clock() globally synchronous | | Alexey Zaytsev reported (and bisected) that the introduction of | cpu_clock() in printk made the timestamps jump back and forth. | | Make cpu_clock() more reliable while still keeping it fast when it's | called frequently. | | Signed-off-by: Ingo Molnar <mingo@elte.hu> causes watchdog triggers when a cpu exits NOHZ state when it has been there for >= the soft lockup threshold, for example here are some messages from a 128 cpu Niagara2 box: [ 168.106406] BUG: soft lockup - CPU#11 stuck for 128s! [dd:3239] [ 168.989592] BUG: soft lockup - CPU#21 stuck for 86s! [swapper:0] [ 168.999587] BUG: soft lockup - CPU#29 stuck for 91s! [make:4511] [ 168.999615] BUG: soft lockup - CPU#2 stuck for 85s! [swapper:0] [ 169.020514] BUG: soft lockup - CPU#37 stuck for 91s! [swapper:0] [ 169.020514] BUG: soft lockup - CPU#45 stuck for 91s! [sh:4515] [ 169.020515] BUG: soft lockup - CPU#69 stuck for 92s! [swapper:0] [ 169.020515] BUG: soft lockup - CPU#77 stuck for 92s! [swapper:0] [ 169.020515] BUG: soft lockup - CPU#61 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#85 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#101 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#109 stuck for 92s! [swapper:0] [ 169.112554] BUG: soft lockup - CPU#117 stuck for 92s! [swapper:0] [ 169.171483] BUG: soft lockup - CPU#40 stuck for 80s! [dd:3239] [ 169.331483] BUG: soft lockup - CPU#13 stuck for 86s! [swapper:0] [ 169.351500] BUG: soft lockup - CPU#43 stuck for 101s! [dd:3239] [ 169.531482] BUG: soft lockup - CPU#9 stuck for 129s! [mkdir:4565] [ 169.595754] BUG: soft lockup - CPU#20 stuck for 93s! [swapper:0] [ 169.626787] BUG: soft lockup - CPU#52 stuck for 93s! [swapper:0] [ 169.626787] BUG: soft lockup - CPU#84 stuck for 92s! [swapper:0] [ 169.636812] BUG: soft lockup - CPU#116 stuck for 94s! [swapper:0] It's simple enough to trigger this by doing a 10 minute sleep after a fresh bootup then starting a parallel kernel build. I suspect this might be reintroducing a problem we've had and fixed before, see the thread: http://marc.info/?l=linux-kernel&m=119546414004065&w=2 <---------------| touch the softlockup watchdog when exiting NOHZ state - we are obviously not locked up. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-19sched: rt-group: synchonised bandwidth periodPeter Zijlstra
Various SMP balancing algorithms require that the bandwidth period run in sync. Possible improvements are moving the rt_bandwidth thing into root_domain and keeping a span per rt_bandwidth which marks throttled cpus. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-17clockevents: optimise tick_nohz_stop_sched_tick() a bitKarsten Wiese
Call ts = &per_cpu(tick_cpu_sched, cpu); and cpu = smp_processor_id(); once instead of twice. No functional change done, as changed code runs with local irq off. Reduces source lines and text size (20bytes on x86_64). [ akpm@linux-foundation.org: Build fix ] Signed-off-by: Karsten Wiese <fzu@wemgehoertderstaat.de> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-03-09time: don't touch an offlined CPU's ts->tick_stopped in ↵Karsten Wiese
tick_cancel_sched_timer() Silences WARN_ONs in rcu_enter_nohz() and rcu_exit_nohz(), which appeared before caused by (repeated) calls to: $ echo 0 > /sys/devices/system/cpu/cpu1/online $ echo 1 > /sys/devices/system/cpu/cpu1/online Signed-off-by: Karsten Wiese <fzu@wemgehoertderstaat.de> Cc: johnstul@us.ibm.com Cc: Rafael Wysocki <rjw@sisk.pl> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@elte.hu> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-02-29rcu: add support for dynamic ticks and preempt rcuSteven Rostedt
The PREEMPT-RCU can get stuck if a CPU goes idle and NO_HZ is set. The idle CPU will not progress the RCU through its grace period and a synchronize_rcu my get stuck. Without this patch I have a box that will not boot when PREEMPT_RCU and NO_HZ are set. That same box boots fine with this patch. This patch comes from the -rt kernel where it has been tested for several months. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-02-08timekeeping: rename timekeeping_is_continuous to timekeeping_valid_for_hresLi Zefan
Function timekeeping_is_continuous() no longer checks flag CLOCK_IS_CONTINUOUS, and it checks CLOCK_SOURCE_VALID_FOR_HRES now. So rename the function accordingly. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-01tick-sched: add more debug informationThomas Gleixner
To allow better diagnosis of tick-sched related, especially NOHZ related problems, we need to know when the last wakeup via an irq happened and when the CPU left the idle state. Add two fields (idle_waketime, idle_exittime) to the tick_sched structure and add them to the timer_list output. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30time: track accurate idle time with tick_sched.idle_sleeptimeVenki Pallipadi
Current idle time in kstat is based on jiffies and is coarse grained. tick_sched.idle_sleeptime is making some attempt to keep track of idle time in a fine grained manner. But, it is not handling the time spent in interrupts fully. Make tick_sched.idle_sleeptime accurate with respect to time spent on handling interrupts and also add tick_sched.idle_lastupdate, which keeps track of last time when idle_sleeptime was updated. This statistics will be crucial for cpufreq-ondemand governor, which can shed some conservative gaurd band that is uses today while setting the frequency. The ondemand changes that uses the exact idle time is coming soon. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30time: more timer related cleanupsPavel Machek
I was confused by FSEC = 10^15 NSEC statement, plus small whitespace fixes. When there's copyright, there should be GPL. Signed-off-by: Pavel Machek <pavel@suse.cz> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30time: timer cleanupsPavel Machek
Small cleanups to tick-related code. Wrong preempt count is followed by BUG(), so it is hardly KERN_WARNING. Signed-off-by: Pavel Machek <pavel@suse.cz> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-25hrtimer: clean up cpu->base locking tricksPeter Zijlstra
In order to more easily allow for the scheduler to use timers, clean up the locking a bit. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>