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* sched: Intoduce get_cpu_iowait_time_us()Arjan van de Ven2010-05-091-0/+28
| | | | | | | | | | | | | | | | | For the ondemand cpufreq governor, it is desired that the iowait time is microaccounted in a similar way as idle time is. This patch introduces the infrastructure to account and expose this information via the get_cpu_iowait_time_us() function. [akpm@linux-foundation.org: fix CONFIG_NO_HZ=n build] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: davej@redhat.com LKML-Reference: <20100509082523.284feab6@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Eliminate the ts->idle_lastupdate fieldArjan van de Ven2010-05-091-4/+1
| | | | | | | | | | | | | | | | | | Now that the only user of ts->idle_lastupdate is update_ts_time_stats(), the entire field can be eliminated. In update_ts_time_stats(), idle_lastupdate is first set to "now", and a few lines later, the only user is an if() statement that assigns a variable either to "now" or to ts->idle_lastupdate, which has the value of "now" at that point. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: davej@redhat.com LKML-Reference: <20100509082439.2fab0b4f@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Fold updating of the last_update_time_info into update_ts_time_stats()Arjan van de Ven2010-05-091-11/+11
| | | | | | | | | | | | | | | | This patch folds the updating of the last_update_time into the update_ts_time_stats() function, and updates the callers. This allows for further cleanups that are done in the next patch. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: davej@redhat.com LKML-Reference: <20100509082403.60072967@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Update the idle statistics in get_cpu_idle_time_us()Arjan van de Ven2010-05-091-1/+6
| | | | | | | | | | | | | | | | | | | | | Right now, get_cpu_idle_time_us() only reports the idle statistics upto the point the CPU entered last idle; not what is valid right now. This patch adds an update of the idle statistics to get_cpu_idle_time_us(), so that calling this function always returns statistics that are accurate at the point of the call. This includes resetting the start of the idle time for accounting purposes to avoid double accounting. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: davej@redhat.com LKML-Reference: <20100509082323.2d2f1945@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Introduce a function to update the idle statisticsArjan van de Ven2010-05-091-10/+19
| | | | | | | | | | | | | | | | Currently, two places update the idle statistics (and more to come later in this series). This patch creates a helper function for updating these statistics. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: davej@redhat.com LKML-Reference: <20100509082245.163e67ed@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Add a comment to get_cpu_idle_time_us()Arjan van de Ven2010-05-091-0/+14
| | | | | | | | | | | | | The exported function get_cpu_idle_time_us() has no comment describing it; add a kerneldoc comment Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: davej@redhat.com LKML-Reference: <20100509082208.7cb721f0@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Rate-limit nohzMike Galbraith2010-03-111-0/+3
| | | | | | | | | | | | | | | Entering nohz code on every micro-idle is costing ~10% throughput for netperf TCP_RR when scheduling cross-cpu. Rate limiting entry fixes this, but raises ticks a bit. On my Q6600, an idle box goes from ~85 interrupts/sec to 128. The higher the context switch rate, the more nohz entry costs. With this patch and some cycle recovery patches in my tree, max cross cpu context switch rate is improved by ~16%, a large portion of which of which is this ratelimiting. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1268301003.6785.28.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'timers-for-linus' of ↵Linus Torvalds2009-12-081-53/+88
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: timers, init: Limit the number of per cpu calibration bootup messages posix-cpu-timers: optimize and document timer_create callback clockevents: Add missing include to pacify sparse x86: vmiclock: Fix printk format x86: Fix printk format due to variable type change sparc: fix printk for change of variable type clocksource/events: Fix fallout of generic code changes nohz: Allow 32-bit machines to sleep for more than 2.15 seconds nohz: Track last do_timer() cpu nohz: Prevent clocksource wrapping during idle nohz: Type cast printk argument mips: Use generic mult/shift factor calculation for clocks clocksource: Provide a generic mult/shift factor calculation clockevents: Use u32 for mult and shift factors nohz: Introduce arch_needs_cpu nohz: Reuse ktime in sub-functions of tick_check_idle. time: Remove xtime_cache time: Implement logarithmic time accumulation
| * nohz: Track last do_timer() cpuThomas Gleixner2009-11-131-24/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The previous patch which limits the sleep time to the maximum deferment time of the time keeping clocksource has some limitations on SMP machines: if all CPUs are idle then for all CPUs the maximum sleep time is limited. Solve this by keeping track of which cpu had the do_timer() duty assigned last and limit the sleep time only for this cpu. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <new-submission> Cc: Jon Hunter <jon-hunter@ti.com> Cc: John Stultz <johnstul@us.ibm.com>
| * nohz: Prevent clocksource wrapping during idleJon Hunter2009-11-131-14/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The dynamic tick allows the kernel to sleep for periods longer than a single tick, but it does not limit the sleep time currently. In the worst case the kernel could sleep longer than the wrap around time of the time keeping clock source which would result in losing track of time. Prevent this by limiting it to the safe maximum sleep time of the current time keeping clock source. The value is calculated when the clock source is registered. [ tglx: simplified the code a bit and massaged the commit msg ] Signed-off-by: Jon Hunter <jon-hunter@ti.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <1250617512-23567-2-git-send-email-jon-hunter@ti.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * nohz: Type cast printk argumentThomas Gleixner2009-11-131-1/+1
| | | | | | | | | | | | | | | | | | On some archs local_softirq_pending() has a data type of unsigned long on others its unsigned int. Type cast it to (unsigned int) in the printk to avoid the compiler warning. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <new-submission>
| * nohz: Introduce arch_needs_cpuMartin Schwidefsky2009-11-051-5/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Allow the architecture to request a normal jiffy tick when the system goes idle and tick_nohz_stop_sched_tick is called . On s390 the hook is used to prevent the system going fully idle if there has been an interrupt other than a clock comparator interrupt since the last wakeup. On s390 the HiperSockets response time for 1 connection ping-pong goes down from 42 to 34 microseconds. The CPU cost decreases by 27%. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> LKML-Reference: <20090929122533.402715150@de.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * nohz: Reuse ktime in sub-functions of tick_check_idle.Martin Schwidefsky2009-11-051-29/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On a system with NOHZ=y tick_check_idle calls tick_nohz_stop_idle and tick_nohz_update_jiffies. Given the right conditions (ts->idle_active and/or ts->tick_stopped) both function get a time stamp with ktime_get. The same time stamp can be reused if both function require one. On s390 this change has the additional benefit that gcc inlines the tick_nohz_stop_idle function into tick_check_idle. The number of instructions to execute tick_check_idle drops from 225 to 144 (without the ktime_get optimization it is 367 vs 215 instructions). before: 0) | tick_check_idle() { 0) | tick_nohz_stop_idle() { 0) | ktime_get() { 0) | read_tod_clock() { 0) 0.601 us | } 0) 1.765 us | } 0) 3.047 us | } 0) | ktime_get() { 0) | read_tod_clock() { 0) 0.570 us | } 0) 1.727 us | } 0) | tick_do_update_jiffies64() { 0) 0.609 us | } 0) 8.055 us | } after: 0) | tick_check_idle() { 0) | ktime_get() { 0) | read_tod_clock() { 0) 0.617 us | } 0) 1.773 us | } 0) | tick_do_update_jiffies64() { 0) 0.593 us | } 0) 4.477 us | } Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: john stultz <johnstul@us.ibm.com> LKML-Reference: <20090929122533.206589318@de.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | NOHZ: update idle state also when NOHZ is inactiveEero Nurkkala2009-10-071-2/+7
|/ | | | | | | | | | | | | | | | | | | | | | | | | | Commit f2e21c9610991e95621a81407cdbab881226419b had unfortunate side effects with cpufreq governors on some systems. If the system did not switch into NOHZ mode ts->inidle is not set when tick_nohz_stop_sched_tick() is called from the idle routine. Therefor all subsequent calls from irq_exit() to tick_nohz_stop_sched_tick() fail to call tick_nohz_start_idle(). This results in bogus idle accounting information which is passed to cpufreq governors. Set the inidle flag unconditionally of the NOHZ active state to keep the idle time accounting correct in any case. [ tglx: Added comment and tweaked the changelog ] Reported-by: Steven Noonan <steven@uplinklabs.net> Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com> Cc: Rik van Riel <riel@redhat.com> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Greg KH <greg@kroah.com> Cc: Steven Noonan <steven@uplinklabs.net> Cc: stable@kernel.org LKML-Reference: <1254907901.30157.93.camel@eenurkka-desktop> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'timers-fixes-for-linus' of ↵Linus Torvalds2009-06-201-3/+9
|\ | | | | | | | | | | | | 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
| * NOHZ: Properly feed cpufreq ondemand governorEero Nurkkala2009-05-271-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | timers: Identifying the existing pinned timersArun R Bharadwaj2009-05-131-3/+4
|/ | | | | | | | | | | | | | * 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>
* time-sched.c: tick_nohz_update_jiffies should be staticJaswinder Singh Rajput2009-01-151-1/+1
| | | | | | | | | | | 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>
* Merge branch 'cputime' of git://git390.osdl.marist.edu/pub/scm/linux-2.6Linus Torvalds2009-01-031-6/+6
|\ | | | | | | | | | | | | | | | | | | * '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
| * [PATCH] idle cputime accountingMartin Schwidefsky2008-12-311-7/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * [PATCH] fix scaled & unscaled cputime accountingMartin Schwidefsky2008-12-311-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | Merge branch 'cpus4096-for-linus-2' of ↵Linus Torvalds2009-01-021-5/+5
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
| * sched: convert nohz_cpu_mask to cpumask_var_t.Rusty Russell2008-11-241-5/+5
| | | | | | | | | | | | | | | | | | | | | | 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>
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*---. \ Merge branches 'timers/clocksource', 'timers/hpet', 'timers/hrtimers', ↵Ingo Molnar2008-12-251-19/+25
|\ \ \ \ | |_|_|/ |/| | | | | | | 'timers/nohz', 'timers/ntp', 'timers/posixtimers' and 'timers/rtc' into timers/core
| | * | nohz: suppress needless timer reprogrammingWoodruff, Richard2008-12-121-17/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| | * | nohz: no softirq pending warnings for offline cpusHeiko Carstens2008-12-121-1/+1
| |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * | hrtimer: removing all ur callback modesPeter Zijlstra2008-11-251-1/+0
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | nohz: disable tick_nohz_kick_tick() for nowThomas Gleixner2008-11-101-0/+4
|/ | | | | | | | | | | | | | | | 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>
* Merge branch 'timers/range-hrtimers' into v28-range-hrtimers-for-linus-v2Thomas Gleixner2008-10-221-12/+13
|\ | | | | | | | | | | | | | | Conflicts: kernel/time/tick-sched.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * Merge commit 'linus/master' into merge-linusArjan van de Ven2008-10-171-7/+19
| |\ | | | | | | | | | | | | | | | Conflicts: arch/x86/kvm/i8254.c
| * | hrtimer: convert kernel/* to the new hrtimer apisArjan van de Ven2008-09-051-11/+10
| | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | NOHZ: fix thinko in the timer restart code pathThomas Gleixner2008-10-211-1/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | NOHZ: restart tick device from irq_enter()Thomas Gleixner2008-10-171-8/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | NOHZ: split tick_nohz_restart_sched_tick()Thomas Gleixner2008-10-171-22/+27
| | | | | | | | | | | | | | | | | | | | | Split out the clock event device reprogramming. Preparatory patch. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | NOHZ: unify the nohz function calls in irq_enter()Thomas Gleixner2008-10-171-1/+12
| |/ |/| | | | | | | | | | | | | 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>
| |
| \
*-. \ Merge branches 'core/softlockup', 'core/softirq', 'core/resources', ↵Ingo Molnar2008-10-151-1/+1
|\ \ \ | | |/ | |/| | | | 'core/printk' and 'core/misc' into core-v28-for-linus
| | * printk: robustify printkPeter Zijlstra2008-08-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | [CPUFREQ][5/6] cpufreq: Changes to get_cpu_idle_time_us(), used by ondemand ↵venkatesh.pallipadi@intel.com2008-10-091-1/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | hrtimer: prevent migration of per CPU hrtimersThomas Gleixner2008-09-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | clockevents: prevent stale tick_next_period for onlining CPUsThomas Gleixner2008-09-231-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | clockevents: prevent cpu online to interfere with nohzThomas Gleixner2008-09-231-4/+4
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | sched_clock: fix NOHZ interactionPeter Zijlstra2008-09-051-0/+3
| | | | | | | | | | | | | | | | | | | | 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>
* | nohz: fix wrong event handler after online an offlined cpuMiao Xie2008-08-211-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | sched clock: revert various sched_clock() changesIngo Molnar2008-07-311-2/+0
|/ | | | | | | | | | | | | | | | | | | | | | | | 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>
* Merge branch 'timers-fixes-for-linus' of ↵Linus Torvalds2008-07-241-2/+10
|\ | | | | | | | | | | | | | | 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
| * Merge branch 'linus' into timers/nohzIngo Molnar2008-07-181-0/+2
| |\
| * | nohz: prevent tick stop outside of the idle loopThomas Gleixner2008-07-181-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | | Merge branch 'linus' into core/softlockupIngo Molnar2008-07-151-0/+10
|\ \ \ | | |/ | |/| | | | | | | | | | | | | | | | Conflicts: kernel/softlockup.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | Merge branch 'timers/for-linus' of ↵Linus Torvalds2008-07-151-0/+8
| |\ \ | | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
| | * nohz: don't stop idle tick if softirqs are pending.Heiko Carstens2008-07-111-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
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