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2008-04-29kernel: use non-racy method for proc entries creationDenis V. Lunev
Use proc_create()/proc_create_data() to make sure that ->proc_fops and ->data be setup before gluing PDE to main tree. Signed-off-by: Denis V. Lunev <den@openvz.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
2008-04-21Merge branch 'master' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt * 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt: hrtimer: optimize the softirq time optimization hrtimer: reduce calls to hrtimer_get_softirq_time() clockevents: fix typo in tick-broadcast.c jiffies: add time_is_after_jiffies and others which compare with jiffies
2008-04-21Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-devel * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-devel: (62 commits) sched: build fix sched: better rt-group documentation sched: features fix sched: /debug/sched_features sched: add SCHED_FEAT_DEADLINE sched: debug: show a weight tree sched: fair: weight calculations sched: fair-group: de-couple load-balancing from the rb-trees sched: fair-group scheduling vs latency sched: rt-group: optimize dequeue_rt_stack sched: debug: add some debug code to handle the full hierarchy sched: fair-group: SMP-nice for group scheduling sched, cpuset: customize sched domains, core sched, cpuset: customize sched domains, docs sched: prepatory code movement sched: rt: multi level group constraints sched: task_group hierarchy sched: fix the task_group hierarchy for UID grouping sched: allow the group scheduler to have multiple levels sched: mix tasks and groups ...
2008-04-21clockevents: fix typo in tick-broadcast.cGlauber Costa
braodcast -> broadcast Signed-off-by: Glauber Costa <gcosta@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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>
2008-04-19x86: tsc prevent time going backwardsThomas Gleixner
We already catch most of the TSC problems by sanity checks, but there is a subtle bug which has been in the code forever. This can cause time jumps in the range of hours. This was reported in: http://lkml.org/lkml/2007/8/23/96 and http://lkml.org/lkml/2008/3/31/23 I was able to reproduce the problem with a gettimeofday loop test on a dual core and a quad core machine which both have sychronized TSCs. The TSCs seems not to be perfectly in sync though, but the kernel is not able to detect the slight delta in the sync check. Still there exists an extremly small window where this delta can be observed with a real big time jump. So far I was only able to reproduce this with the vsyscall gettimeofday implementation, but in theory this might be observable with the syscall based version as well. CPU 0 updates the clock source variables under xtime/vyscall lock and CPU1, where the TSC is slighty behind CPU0, is reading the time right after the seqlock was unlocked. The clocksource reference data was updated with the TSC from CPU0 and the value which is read from TSC on CPU1 is less than the reference data. This results in a huge delta value due to the unsigned subtraction of the TSC value and the reference value. This algorithm can not be changed due to the support of wrapping clock sources like pm timer. The huge delta is converted to nanoseconds and added to xtime, which is then observable by the caller. The next gettimeofday call on CPU1 will show the correct time again as now the TSC has advanced above the reference value. To prevent this TSC specific wreckage we need to compare the TSC value against the reference value and return the latter when it is larger than the actual TSC value. I pondered to mark the TSC unstable when the readout is smaller than the reference value, but this would render an otherwise good and fast clocksource unusable without a real good reason. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-18Merge git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrtLinus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt: clocksource: make clocksource watchdog cycle through online CPUs Documentation: move timer related documentation to a single place clockevents: optimise tick_nohz_stop_sched_tick() a bit locking: remove unused double_spin_lock() hrtimers: simplify lockdep handling timers: simplify lockdep handling posix-timers: fix shadowed variables timer_list: add annotations to workqueue.c hrtimer: use nanosleep specific restart_block fields hrtimer: add nanosleep specific restart_block member
2008-04-18Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdbLinus Torvalds
* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-kgdb: kgdb: always use icache flush for sw breakpoints kgdb: fix SMP NMI kgdb_handle_exception exit race kgdb: documentation fixes kgdb: allow static kgdbts boot configuration kgdb: add documentation kgdb: Kconfig fix kgdb: add kgdb internal test suite kgdb: fix several kgdb regressions kgdb: kgdboc pl011 I/O module kgdb: fix optional arch functions and probe_kernel_* kgdb: add x86 HW breakpoints kgdb: print breakpoint removed on exception kgdb: clocksource watchdog kgdb: fix NMI hangs kgdb: fix kgdboc dynamic module configuration kgdb: document parameters x86: kgdb support consoles: polling support, kgdboc kgdb: core uaccess: add probe_kernel_write()
2008-04-17kgdb: clocksource watchdogJason Wessel
In order to not trip the clocksource watchdog, kgdb must touch the clocksource watchdog on the return to normal system run state. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-17clocksource: make clocksource watchdog cycle through online CPUsAndi Kleen
This way it checks if the clocks are synchronized between CPUs too. This might be able to detect slowly drifting TSCs which only go wrong over longer time. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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>
2008-04-17[S390] genirq/clockevents: move irq affinity prototypes/inlines to interrupt.hRussell King
> Generic code is not supposed to include irq.h. Replace this include > by linux/hardirq.h instead and add/replace an include of linux/irq.h > in asm header files where necessary. > This change should only matter for architectures that make use of > GENERIC_CLOCKEVENTS. > Architectures in question are mips, x86, arm, sh, powerpc, uml and sparc64. > > I did some cross compile tests for mips, x86_64, arm, powerpc and sparc64. > This patch fixes also build breakages caused by the include replacement in > tick-common.h. I generally dislike adding optional linux/* includes in asm/* includes - I'm nervous about this causing include loops. However, there's a separate point to be discussed here. That is, what interfaces are expected of every architecture in the kernel. If generic code wants to be able to set the affinity of interrupts, then that needs to become part of the interfaces listed in linux/interrupt.h rather than linux/irq.h. So what I suggest is this approach instead (against Linus' tree of a couple of days ago) - we move irq_set_affinity() and irq_can_set_affinity() to linux/interrupt.h, change the linux/irq.h includes to linux/interrupt.h and include asm/irq_regs.h where needed (asm/irq_regs.h is supposed to be rarely used include since not much touches the stacked parent context registers.) Build tested on ARM PXA family kernels and ARM's Realview platform kernels which both use genirq. [ tglx@linutronix.de: add GENERIC_HARDIRQ dependencies ] Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2008-03-25clocksource: revert: use init_timer_deferrable for clocksource_watchdogThomas Gleixner
Revert commit 1077f5a917b7c630231037826b344b2f7f5b903f Author: Parag Warudkar <parag.warudkar@gmail.com> Date: Wed Jan 30 13:30:01 2008 +0100 clocksource.c: use init_timer_deferrable for clocksource_watchdog clocksource_watchdog can use a deferrable timer - reduces wakeups from idle per second. The watchdog timer needs to run with the specified interval. Otherwise it will miss the possible wrap of the watchdog clocksource. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org
2008-03-24Don't 'printk()' while holding xtime lock for writingLinus Torvalds
The printk() can deadlock because it can wake up klogd(), and task enqueueing will try to read the time in order to set a hrtimer. Reported-by: Marcin Slusarz <marcin.slusarz@gmail.com> Debugged-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-19revert "clocksource: make clocksource watchdog cycle through online CPUs"Andrew Morton
Revert commit 1ada5cba6a0318f90e45b38557e7b5206a9cba38 ("clocksource: make clocksource watchdog cycle through online CPUs") due to the regression reported by Gabriel C at http://lkml.org/lkml/2008/2/24/281 (short vesion: it makes TSC be marked as always unstable on his machine). Cc: Andi Kleen <ak@suse.de> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Robert Hancock <hancockr@shaw.ca> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Gabriel C <nix.or.die@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-09time: remove obsolete CLOCK_TICK_ADJUSTRoman Zippel
The first version of the ntp_interval/tick_length inconsistent usage patch was recently merged as bbe4d18ac2e058c56adb0cd71f49d9ed3216a405 http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bbe4d18ac2e058c56adb0cd71f49d9ed3216a405 While the fix did greatly improve the situation, it was correctly pointed out by Roman that it does have a small bug: If the users change clocksources after the system has been running and NTP has made corrections, the correctoins made against the old clocksource will be applied against the new clocksource, causing error. The second attempt, which corrects the issue in the NTP_INTERVAL_LENGTH definition has also made it up-stream as commit e13a2e61dd5152f5499d2003470acf9c838eab84 http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e13a2e61dd5152f5499d2003470acf9c838eab84 Roman has correctly pointed out that CLOCK_TICK_ADJUST is calculated based on the PIT's frequency, and isn't really relevant to non-PIT driven clocksources (that is, clocksources other then jiffies and pit). This patch reverts both of those changes, and simply removes CLOCK_TICK_ADJUST. This does remove the granularity error correction for users of PIT and Jiffies clocksource users, but the granularity error but for the majority of users, it should be within the 500ppm range NTP can accommodate for. For systems that have granularity errors greater then 500ppm, the "ntp_tick_adj=" boot option can be used to compensate. [johnstul@us.ibm.com: provided changelog] [mattilinnanvuori@yahoo.com: maek ntp_tick_adj static] Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Acked-by: john stultz <johnstul@us.ibm.com> Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: mingo@elte.hu 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>
2008-03-09ntp: use unsigned input for do_div()David Howells
The kernel NTP code shouldn't hand 64-bit *signed* values to do_div(). Make it instead hand 64-bit unsigned values. This gets rid of a couple of warnings. Signed-off-by: David Howells <dhowells@redhat.com> Cc: Roman Zippel <zippel@linux-m68k.org> 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: 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>
2008-02-17timer_list: print relative expiry time signedPavel Machek
Relative expiry time can get negative, so it should be signed. Signed-off-by: Pavel Machek <Pavel@suse.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-02-10ntp: correct inconsistent interval/tick_length usagejohn stultz
clocksource initialization and error accumulation. This corrects a 280ppm drift seen on some systems using acpi_pm, and affects other clocksources as well (likely to a lesser degree). Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Steven Rostedt <rostedt@goodmis.org> 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>
2008-02-08time: fix typo in commentsLi Zefan
Fix typo in comments. BTW: I have to fix coding style in arch/ia64/kernel/time.c also, otherwise checkpatch.pl will be complaining. 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>
2008-02-08timekeeping: 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>
2008-02-08clockevent: simplify list operationsLi Zefan
list_for_each_safe() suffices here. 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>
2008-02-08clocksource: remove redundant codeLi Zefan
Flag CLOCK_SOURCE_WATCHDOG is cleared twice. Note clocksource_change_rating() won't do anyting with the cs flag. 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>
2008-02-06time: fix sysfs_show_{available,current}_clocksources() buffer overflow problemMiao Xie
I found that there is a buffer overflow problem in the following code. Version: 2.6.24-rc2, File: kernel/time/clocksource.c:417-432 -------------------------------------------------------------------- static ssize_t sysfs_show_available_clocksources(struct sys_device *dev, char *buf) { struct clocksource *src; char *curr = buf; spin_lock_irq(&clocksource_lock); list_for_each_entry(src, &clocksource_list, list) { curr += sprintf(curr, "%s ", src->name); } spin_unlock_irq(&clocksource_lock); curr += sprintf(curr, "\n"); return curr - buf; } ----------------------------------------------------------------------- sysfs_show_current_clocksources() also has the same problem though in practice the size of current clocksource's name won't exceed PAGE_SIZE. I fix the bug by using snprintf according to the specification of the kernel (Version:2.6.24-rc2,File:Documentation/filesystems/sysfs.txt) Fix sysfs_show_available_clocksources() and sysfs_show_current_clocksources() buffer overflow problem with snprintf(). Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Cc: WANG Cong <xiyou.wangcong@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> 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>
2008-02-01timekeeping: update xtime_cache when time(zone) changesThomas Gleixner
xtime_cache needs to be updated whenever xtime and or wall_to_monotic are changed. Otherwise users of xtime_cache might see a stale (and in the case of timezone changes utterly wrong) value until the next update happens. Fixup the obvious places, which miss this update. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Tested-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> 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>
2008-01-30NTP: correct inconsistent ntp interval/tick_length usagejohn stultz
I recently noticed on one of my boxes that when synched with an NTP server, the drift value reported for the system was ~283ppm. While in some cases, clock hardware can be that bad, it struck me as unusual as the system was using the acpi_pm clocksource, which is one of the more trustworthy and accurate clocksources on x86 hardware. I brought up another system and let it sync to the same NTP server, and I noticed a similar 280some ppm drift. In looking at the code, I found that the acpi_pm's constant frequency was being computed correctly at boot-up, however once the system was up, even without the ntp daemon running, the clocksource's frequency was being modified by the clocksource_adjust() function. Digging deeper, I realized that in the code that keeps track of how much the clocksource is skewing from the ntp desired time, we were using different lengths to establish how long an time interval was. The clocksource was being setup with the following interval: NTP_INTERVAL_LENGTH = NSEC_PER_SEC/NTP_INTERVAL_FREQ While the ntp code was using the tick_length_base value: tick_length_base ~= (tick_usec * NSEC_PER_USEC * USER_HZ) /NTP_INTERVAL_FREQ The subtle difference is: (tick_usec * NSEC_PER_USEC * USER_HZ) != NSEC_PER_SEC This difference in calculation was causing the clocksource correction code to apply a correction factor to the clocksource so the two intervals were the same, however this results in the actual frequency of the clocksource to be made incorrect. I believe this difference would affect all clocksources, although to differing degrees depending on the clocksource resolution. The issue was introduced when my HZ free ntp patch landed in 2.6.21-rc1, so my apologies for the mistake, and for not noticing it until now. The following patch, corrects the clocksource's initialization code so it uses the same interval length as the code in ntp.c. After applying this patch, the drift value for the same system went from ~283ppm to only 2.635ppm. I believe this patch to be good, however it does affect all arches and I've only tested on x86, so some caution is advised. I do think it would be a likely candidate for a stable 2.6.24.x release. Any thoughts or feedback would be appreciated. Signed-off-by: John Stultz <johnstul@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30x86: make clockevents more robustIngo Molnar
detect zero event-device multiplicators - they then cause division-by-zero crashes if a clockevent has been initialized incorrectly. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30clocksource: add unregister function to disable unusable clocksourcesThomas Gleixner
On x86 the PIT might become an unusable clocksource. Add an unregister function to provide a possibilty to remove the PIT from the list of available clock sources. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30clocksource: make clocksource watchdog cycle through online CPUsAndi Kleen
This way it checks if the clocks are synchronized between CPUs too. This might be able to detect slowly drifting TSCs which only go wrong over longer time. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30clocksource.c: use init_timer_deferrable for clocksource_watchdogParag Warudkar
clocksource_watchdog can use a deferrable timer - reduces wakeups from idle per second. Signed-off-by: Parag Warudkar <parag.warudkar@gmail.com> 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>
2008-01-30time: fold __get_realtime_clock_ts() into getnstimeofday()Geert Uytterhoeven
- getnstimeofday() was just a wrapper around __get_realtime_clock_ts() - Replace calls to __get_realtime_clock_ts() by calls to getnstimeofday() - Fix bogus reference to get_realtime_clock_ts(), which never existed Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> 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>
2008-01-30timer: clean up tick-broadcast.cThomas Gleixner
clean up tick-broadcast.c Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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>
2008-01-25sched: rt throttling vs no_hzPeter Zijlstra
We need to teach no_hz about the rt throttling because its tick driven. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-24Driver core: change sysdev classes to use dynamic kobject namesKay Sievers
All kobjects require a dynamically allocated name now. We no longer need to keep track if the name is statically assigned, we can just unconditionally free() all kobject names on cleanup. Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-12-18clockevents: fix reprogramming decision in oneshot broadcastThomas Gleixner
Resolve the following regression of a choppy, almost unusable laptop: http://lkml.org/lkml/2007/12/7/299 http://bugzilla.kernel.org/show_bug.cgi?id=9525 A previous version of the code did the reprogramming of the broadcast device in the return from idle code. This was removed, but the logic in tick_handle_oneshot_broadcast() was kept the same. When a broadcast interrupt happens we signal the expiry to all CPUs which have an expired event. If none of the CPUs has an expired event, which can happen in dyntick mode, then we reprogram the broadcast device. We do not reprogram otherwise, but this is only correct if all CPUs, which are in the idle broadcast state have been woken up. The code ignores, that there might be pending not yet expired events on other CPUs, which are in the idle broadcast state. So the delivery of those events can be delayed for quite a time. Change the tick_handle_oneshot_broadcast() function to check for CPUs, which are in broadcast state and are not woken up by the current event, and enforce the rearming of the broadcast device for those CPUs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-12-07clockevents: warn once when program_event() is called with negative expiryThomas Gleixner
The hrtimer problem with large relative timeouts resulting in a negative expiry time went unnoticed as there is no check in the clockevents_program_event() code. Put a check there with a WARN_ONCE to avoid such problems in the future. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-28softlockup: fix false positives on CONFIG_NOHZThomas Gleixner
David Miller reported soft lockup false-positives that trigger on NOHZ due to CPUs idling for more than 10 seconds. The solution is touch the softlockup watchdog when we return from idle. (by definition we are not 'locked up' when we were idle) http://bugzilla.kernel.org/show_bug.cgi?id=9409 Reported-by: David Miller <davem@davemloft.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-26time: add ADJ_OFFSET_SS_READJohn Stultz
Michael Kerrisk reported that a long standing bug in the adjtimex() system call causes glibc's adjtime(3) function to deliver the wrong results if 'delta' is NULL. add the ADJ_OFFSET_SS_READ API detail, which will be used by glibc to fix this API compatibility bug. Also see: http://bugzilla.kernel.org/show_bug.cgi?id=6761 [ mingo@elte.hu: added patch description and made it backwards compatible ] NOTE: the new flag is defined 0xa001 so that it returns -EINVAL on older kernels - this way glibc can use it safely. Suggested by Ulrich Drepper. Acked-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-11-17ntp: fix typo that makes sync_cmos_clock erraticDavid P. Reed
Fix a typo in ntp.c that has caused updating of the persistent (RTC) clock when synced to NTP to behave erratically. When debugging a freeze that arises on my AMD64 machines when I run the ntpd service, I added a number of printk's to monitor the sync_cmos_clock procedure. I discovered that it was not syncing to cmos RTC every 11 minutes as documented, but instead would keep trying every second for hours at a time. The reason turned out to be a typo in sync_cmos_clock, where it attempts to ensure that update_persistent_clock is called very close to 500 msec. after a 1 second boundary (required by the PC RTC's spec). That typo referred to "xtime" in one spot, rather than "now", which is derived from "xtime" but not equal to it. This makes the test erratic, creating a "coin-flip" that decides when update_persistent_clock is called - when it is called, which is rarely, it may be at any time during the one second period, rather than close to 500 msec, so the value written is needlessly incorrect, too. Signed-off-by: David P. Reed Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-11-05time: fix inconsistent function names in commentsLi Zefan
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Thomas Gleixner <tglx@linutronix.de> 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>
2007-10-29timer_list: Fix printk format stringsVegard Nossum
This makes sure printk format strings contain no more than a single line. Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-29clockevents: unexport tick_nohz_get_sleep_lengthAdrian Bunk
This patch removes the unused EXPORT_SYMBOL_GPL(tick_nohz_get_sleep_length). Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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