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* hrtimers: Fix typo causing erratic timersThomas Gleixner2011-05-251-1/+1
| | | | | | | | | | | | | | | | | commit 9ec2690758a5 ("timerfd: Manage cancelable timers in timerfd") introduced a CONFIG_HIGHRES_TIMERS (should be CONFIG_HIGH_RES_TIMERS) typo, which caused applications depending on CLOCK_REALTIME timers to become sluggy due to the fact that the time base of the realtime timers was not updated when the wall clock time was set. This causes anything from 100% CPU use for some applications to odd delays and hickups. Reported-bisected-and-tested-by: Anca Emanuel <anca.emanuel@gmail.com> Tested-by: Linus Torvalds <torvalds@linux-foundation.org> Fatfingered-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hrtimers: Reorder clock basesThomas Gleixner2011-05-231-6/+6
| | | | | | | | | | | | | | | | | The ordering of the clock bases is historical due to the CLOCK_REALTIME and CLOCK_MONOTONIC constants. Now the hrtimer bases have their own enumeration due to the gap between CLOCK_MONOTONIC and CLOCK_BOOTTIME. So we can be more clever as most timers end up on the CLOCK_MONOTONIC base due to the virtue of POSIX declaring that relative CLOCK_REALTIME timers are not affected by time changes. In desktop environments this is slowly changing as applications switch to absolute timers, but I've observed empty CLOCK_REALTIME bases often enough. There is no performance penalty or overhead when CLOCK_REALTIME timers are active, but in case they are not we don't skip over a full cache line. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Peter Zijlstra <peterz@infradead.org>
* hrtimers: Avoid touching inactive timer basesThomas Gleixner2011-05-231-11/+18
| | | | | | | | Instead of iterating over all possible timer bases avoid it by marking the active bases in the cpu base. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Peter Zijlstra <peterz@infradead.org>
* timerfd: Manage cancelable timers in timerfdThomas Gleixner2011-05-231-62/+32
| | | | | | | | | | | | | Peter is concerned about the extra scan of CLOCK_REALTIME_COS in the timer interrupt. Yes, I did not think about it, because the solution was so elegant. I didn't like the extra list in timerfd when it was proposed some time ago, but with a rcu based list the list walk it's less horrible than the original global lock, which was held over the list iteration. Requested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Peter Zijlstra <peterz@infradead.org>
* timerfd: Allow timers to be cancelled when clock was setThomas Gleixner2011-05-021-1/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some applications must be aware of clock realtime being set backward. A simple example is a clock applet which arms a timer for the next minute display. If clock realtime is set backward then the applet displays a stale time for the amount of time which the clock was set backwards. Due to that applications poll the time because we don't have an interface. Extend the timerfd interface by adding a flag which puts the timer onto a different internal realtime clock. All timers on this clock are expired whenever the clock was set. The timerfd core records the monotonic offset when the timer is created. When the timer is armed, then the current offset is compared to the previous recorded offset. When it has changed, then timerfd_settime returns -ECANCELED. When a timer is read the offset is compared and if it changed -ECANCELED returned to user space. Periodic timers are not rearmed in the cancelation case. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <johnstul@us.ibm.com> Cc: Chris Friesen <chris.friesen@genband.com> Tested-by: Kay Sievers <kay.sievers@vrfy.org> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Davide Libenzi <davidel@xmailserver.org> Reviewed-by: Alexander Shishkin <virtuoso@slind.org> Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1104271359580.3323%40ionos%3E Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* hrtimers: Prepare for cancel on clock was set timersThomas Gleixner2011-05-021-64/+61
| | | | | | | | Make clock_was_set() unconditional and rename hres_timers_resume to hrtimers_resume. This is a preparatory patch for hrtimers which are cancelled when clock realtime was set. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* hrtimer: Make lookup table constMike Frysinger2011-05-021-1/+1
| | | | | | Signed-off-by: Mike Frysinger <vapier@gentoo.org> Link: http://lkml.kernel.org/r/%3C1304364267-14489-1-git-send-email-vapier%40gentoo.org%3E Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* hrtimer: Initialize CLOCK_ID to HRTIMER_BASE table staticallyThomas Gleixner2011-04-291-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Sedat and Bruno reported RCU stalls which turned out to be caused by the following; sched_init() calls init_rt_bandwidth() which calls hrtimer_init() _BEFORE_ hrtimers_init() is called. While not entirely correct this worked because hrtimer_init() only accessed statically initialized data (hrtimer_bases.clock_base[CLOCK_MONOTONIC]) Commit e06383db9 (hrtimers: extend hrtimer base code to handle more then 2 clockids) added an indirection to the hrtimer_bases.clock_base lookup to avoid gap handling in the hot path. The table which is used for the translataion from CLOCK_ID to HRTIMER_BASE index is initialized at runtime in hrtimers_init(). So the early call of the scheduler code translates CLOCK_MONOTONIC to HRTIMER_BASE_REALTIME. Thus the rt_bandwith timer ends up on CLOCK_REALTIME. If the timer is armed and the wall clock time is set (e.g. ntpdate in the early boot process - which also gives the problem deterministic behaviour i.e. magic recovery after N hours), then the timer ends up with an expiry time far into the future. That breaks the RT throttler mechanism as rt runtime is accumulated and never cleared, so the rt throttler detects a false cpu hog condition and blocks all RT tasks until the timer finally expires. That in turn stalls the RCU thread of TINYRCU which leads to an huge amount of RCU callbacks piling up. Make the translation table statically initialized, so we are back to the status of <= 2.6.39. Reported-and-tested-by: Sedat Dilek <sedat.dilek@gmail.com> Reported-by: Bruno Prémont <bonbons@linux-vserver.org> Cc: John stultz <johnstul@us.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1104282353140.3005%40ionos%3E Reviewed-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'timers-core-for-linus' of ↵Linus Torvalds2011-03-151-39/+45
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (62 commits) posix-clocks: Check write permissions in posix syscalls hrtimer: Remove empty hrtimer_init_hres_timer() hrtimer: Update hrtimer->state documentation hrtimer: Update base[CLOCK_BOOTTIME].offset correctly timers: Export CLOCK_BOOTTIME via the posix timers interface timers: Add CLOCK_BOOTTIME hrtimer base time: Extend get_xtime_and_monotonic_offset() to also return sleep time: Introduce get_monotonic_boottime and ktime_get_boottime hrtimers: extend hrtimer base code to handle more then 2 clockids ntp: Remove redundant and incorrect parameter check mn10300: Switch do_timer() to xtimer_update() posix clocks: Introduce dynamic clocks posix-timers: Cleanup namespace posix-timers: Add support for fd based clocks x86: Add clock_adjtime for x86 posix-timers: Introduce a syscall for clock tuning. time: Splitout compat timex accessors ntp: Add ADJ_SETOFFSET mode bit time: Introduce timekeeping_inject_offset posix-timer: Update comment ... Fix up new system-call-related conflicts in arch/x86/ia32/ia32entry.S arch/x86/include/asm/unistd_32.h arch/x86/include/asm/unistd_64.h arch/x86/kernel/syscall_table_32.S (name_to_handle_at()/open_by_handle_at() vs clock_adjtime()), and some due to movement of get_jiffies_64() in: kernel/time.c
| * hrtimer: Remove empty hrtimer_init_hres_timer()Thomas Gleixner2011-03-101-10/+0
| | | | | | | | | | | | Leftover from earlier implementation. All empty, remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * hrtimer: Update base[CLOCK_BOOTTIME].offset correctlyThomas Gleixner2011-03-021-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | We calculate the current time of each clock base by adding an offset to clock_monotonic. The offset for the clock bases is set in retrigger_next_event() which is called when we switch a cpu to highres mode or when the clock was set. Add the missing update for clock boottime. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <johnstul@us.ibm.com>
| * timers: Add CLOCK_BOOTTIME hrtimer baseJohn Stultz2011-02-211-4/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | CLOCK_MONOTONIC stops while the system is in suspend. This is because to applications system suspend is invisible. However, there is a growing set of applications that are wanting to be suspend-aware, but do not want to deal with the complications of CLOCK_REALTIME (which might jump around if settimeofday is called). For these applications, I propose a new clockid: CLOCK_BOOTTIME. CLOCK_BOOTTIME is idential to CLOCK_MONOTONIC, except it also includes any time spent in suspend. This patch add hrtimer base for CLOCK_BOOTTIME, using get_monotonic_boottime/ktime_get_boottime, to allow in kernel users to set timers against. CC: Jamie Lokier <jamie@shareable.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Alexander Shishkin <virtuoso@slind.org> CC: Arve Hjønnevåg <arve@android.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
| * time: Extend get_xtime_and_monotonic_offset() to also return sleepJohn Stultz2011-02-211-4/+5
| | | | | | | | | | | | | | | | | | | | | | Extend get_xtime_and_monotonic_offset to get_xtime_and_monotonic_and_sleep_offset(). CC: Jamie Lokier <jamie@shareable.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Alexander Shishkin <virtuoso@slind.org> CC: Arve Hjønnevåg <arve@android.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
| * hrtimers: extend hrtimer base code to handle more then 2 clockidsJohn Stultz2011-02-211-13/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The hrtimer code is written mainly with CLOCK_REALTIME and CLOCK_MONOTONIC in mind. These are clockids 0 and 1 resepctively. However, if we are to introduce any new hrtimer bases, using new clockids, we have to skip the cputimers (clockids 2,3) as well as other clockids that may not impelement timers. This patch adds a little bit of indirection between the clockid and the base, so that we can extend the base by one when we add a new clockid at number 7 or so. CC: Jamie Lokier <jamie@shareable.org> CC: Thomas Gleixner <tglx@linutronix.de> CC: Alexander Shishkin <virtuoso@slind.org> CC: Arve Hjønnevåg <arve@android.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
| * time: Provide get_xtime_and_monotonic_offset()Torben Hohn2011-01-311-11/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The hrtimer code accesses timekeeping variables under xtime_lock. Provide a sensible accessor function and use it. [ tglx: Removed the conditionals, unused variable, fixed codingstyle and massaged changelog ] Signed-off-by: Torben Hohn <torbenh@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org LKML-Reference: <20110127145905.23248.30458.stgit@localhost> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | debugobjects: Add hint for better object identificationStanislaw Gruszka2011-03-081-0/+6
|/ | | | | | | | | | | | | | | | | | | In complex subsystems like mac80211 structures can contain several timers and work structs, so identifying a specific instance from the call trace and object type output of debugobjects can be hard. Allow the subsystems which support debugobjects to provide a hint function. This function returns a pointer to a kernel address (preferrably the objects callback function) which is printed along with the debugobjects type. Add hint methods for timer_list, work_struct and hrtimer. [ tglx: Massaged changelog, made it compile ] Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> LKML-Reference: <20110307085809.GA9334@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'for-next' of ↵Linus Torvalds2011-01-131-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial * 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits) Documentation/trace/events.txt: Remove obsolete sched_signal_send. writeback: fix global_dirty_limits comment runtime -> real-time ppc: fix comment typo singal -> signal drivers: fix comment typo diable -> disable. m68k: fix comment typo diable -> disable. wireless: comment typo fix diable -> disable. media: comment typo fix diable -> disable. remove doc for obsolete dynamic-printk kernel-parameter remove extraneous 'is' from Documentation/iostats.txt Fix spelling milisec -> ms in snd_ps3 module parameter description Fix spelling mistakes in comments Revert conflicting V4L changes i7core_edac: fix typos in comments mm/rmap.c: fix comment sound, ca0106: Fix assignment to 'channel'. hrtimer: fix a typo in comment init/Kconfig: fix typo anon_inodes: fix wrong function name in comment fix comment typos concerning "consistent" poll: fix a typo in comment ... Fix up trivial conflicts in: - drivers/net/wireless/iwlwifi/iwl-core.c (moved to iwl-legacy.c) - fs/ext4/ext4.h Also fix missed 'diabled' typo in drivers/net/bnx2x/bnx2x.h while at it.
| * hrtimer: fix a typo in commentNamhyung Kim2010-12-221-1/+1
| | | | | | | | | | Signed-off-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* | Merge branch 'for-2.6.38' of ↵Linus Torvalds2011-01-071-1/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits) gameport: use this_cpu_read instead of lookup x86: udelay: Use this_cpu_read to avoid address calculation x86: Use this_cpu_inc_return for nmi counter x86: Replace uses of current_cpu_data with this_cpu ops x86: Use this_cpu_ops to optimize code vmstat: User per cpu atomics to avoid interrupt disable / enable irq_work: Use per cpu atomics instead of regular atomics cpuops: Use cmpxchg for xchg to avoid lock semantics x86: this_cpu_cmpxchg and this_cpu_xchg operations percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support percpu,x86: relocate this_cpu_add_return() and friends connector: Use this_cpu operations xen: Use this_cpu_inc_return taskstats: Use this_cpu_ops random: Use this_cpu_inc_return fs: Use this_cpu_inc_return in buffer.c highmem: Use this_cpu_xx_return() operations vmstat: Use this_cpu_inc_return for vm statistics x86: Support for this_cpu_add, sub, dec, inc_return percpu: Generic support for this_cpu_add, sub, dec, inc_return ... Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c} as per Tejun.
| * | core: Replace __get_cpu_var with __this_cpu_read if not used for an address.Christoph Lameter2010-12-171-1/+1
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __get_cpu_var() can be replaced with this_cpu_read and will then use a single read instruction with implied address calculation to access the correct per cpu instance. However, the address of a per cpu variable passed to __this_cpu_read() cannot be determined (since it's an implied address conversion through segment prefixes). Therefore apply this only to uses of __get_cpu_var where the address of the variable is not used. Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Hugh Dickins <hughd@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | Merge branch 'timers-for-linus' of ↵Linus Torvalds2011-01-061-56/+27
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: MAINTAINERS: Update timer related entries timers: Use this_cpu_read timerqueue: Make timerqueue_getnext() static inline hrtimer: fix timerqueue conversion flub hrtimers: Convert hrtimers to use timerlist infrastructure timers: Fixup allmodconfig build issue timers: Rename timerlist infrastructure to timerqueue timers: Introduce timerlist infrastructure. hrtimer: Remove stale comment on curr_timer timer: Warn when del_timer_sync() is called in hardirq context timer: Del_timer_sync() can be used in softirq context timer: Make try_to_del_timer_sync() the same on SMP and UP posix-timers: Annotate lock_timer() timer: Permit statically-declared work with deferrable timers time: Use ARRAY_SIZE macro in timecompare.c timer: Initialize the field slack of timer_list timer_list: Remove alignment padding on 64 bit when CONFIG_TIMER_STATS time: Compensate for rounding on odd-frequency clocksources Fix up trivial conflict in MAINTAINERS
| * hrtimer: fix timerqueue conversion flubJohn Stultz2010-12-101-5/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | In converting the hrtimers to timerqueue, I missed a spot in hrtimer_run_queues where we loop running timers. We end up not pulling the new next value out and instead just use the last next value, causing boot time hangs in some cases. The proper fix is to pull timerqueue_getnext each iteration instead of using a local next value. Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: John Stultz <john.stultz@linaro.org>
| * hrtimers: Convert hrtimers to use timerlist infrastructureJohn Stultz2010-12-101-56/+30
| | | | | | | | | | | | | | | | | | | | | | Converts the hrtimer code to use the new timerlist infrastructure Signed-off-by: John Stultz <john.stultz@linaro.org> LKML Reference: <1290136329-18291-3-git-send-email-john.stultz@linaro.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> CC: Alessandro Zummo <a.zummo@towertech.it> CC: Thomas Gleixner <tglx@linutronix.de> CC: Richard Cochran <richardcochran@gmail.com>
* | hrtimer: Preserve timer state in remove_hrtimer()Salman Qazi2010-10-141-2/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The race is described as follows: CPU X CPU Y remove_hrtimer // state & QUEUED == 0 timer->state = CALLBACK unlock timer base timer->f(n) //very long hrtimer_start lock timer base remove_hrtimer // no effect hrtimer_enqueue timer->state = CALLBACK | QUEUED unlock timer base hrtimer_start lock timer base remove_hrtimer mode = INACTIVE // CALLBACK bit lost! switch_hrtimer_base CALLBACK bit not set: timer->base changes to a different CPU. lock this CPU's timer base The bug was introduced with commit ca109491f (hrtimer: removing all ur callback modes) in 2.6.29 [ tglx: Feed new state via local variable and add a comment. ] Signed-off-by: Salman Qazi <sqazi@google.com> Cc: akpm@linux-foundation.org Cc: Peter Zijlstra <peterz@infradead.org> LKML-Reference: <20101012142351.8485.21823.stgit@dungbeetle.mtv.corp.google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org
* | gcc-4.6: kernel/*: Fix unused but set warningsAndi Kleen2010-09-051-2/+1
|/ | | | | | | | | | No real bugs I believe, just some dead code. Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: andi@firstfloor.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'timers-timekeeping-for-linus' of ↵Linus Torvalds2010-08-061-5/+4
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timers-timekeeping-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: um: Fix read_persistent_clock fallout kgdb: Do not access xtime directly powerpc: Clean up obsolete code relating to decrementer and timebase powerpc: Rework VDSO gettimeofday to prevent time going backwards clocksource: Add __clocksource_updatefreq_hz/khz methods x86: Convert common clocksources to use clocksource_register_hz/khz timekeeping: Make xtime and wall_to_monotonic static hrtimer: Cleanup direct access to wall_to_monotonic um: Convert to use read_persistent_clock timkeeping: Fix update_vsyscall to provide wall_to_monotonic offset powerpc: Cleanup xtime usage powerpc: Simplify update_vsyscall time: Kill off CONFIG_GENERIC_TIME time: Implement timespec_add x86: Fix vtime/file timestamp inconsistencies Trivial conflicts in Documentation/feature-removal-schedule.txt Much less trivial conflicts in arch/powerpc/kernel/time.c resolved as per Thomas' earlier merge commit 47916be4e28c ("Merge branch 'powerpc.cherry-picks' into timers/clocksource")
| * hrtimer: Cleanup direct access to wall_to_monotonicJohn Stultz2010-07-271-5/+4
| | | | | | | | | | | | | | | | | | | | | | | | Provides an accessor function to replace hrtimer.c's direct access of wall_to_monotonic. This will allow wall_to_monotonic to be made static as planned in Documentation/feature-removal-schedule.txt Signed-off-by: John Stultz <johnstul@us.ibm.com> LKML-Reference: <1279068988-21864-9-git-send-email-johnstul@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | sched: Change nohz idle load balancing logic to push modelVenkatesh Pallipadi2010-06-091-6/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the new push model, all idle CPUs indeed go into nohz mode. There is still the concept of idle load balancer (performing the load balancing on behalf of all the idle cpu's in the system). Busy CPU kicks the nohz balancer when any of the nohz CPUs need idle load balancing. The kickee CPU does the idle load balancing on behalf of all idle CPUs instead of the normal idle balance. This addresses the below two problems with the current nohz ilb logic: * the idle load balancer continued to have periodic ticks during idle and wokeup frequently, even though it did not have any rebalancing to do on behalf of any of the idle CPUs. * On x86 and CPUs that have APIC timer stoppage on idle CPUs, this periodic wakeup can result in a periodic additional interrupt on a CPU doing the timer broadcast. Also currently we are migrating the unpinned timers from an idle to the cpu doing idle load balancing (when all the cpus in the system are idle, there is no idle load balancing cpu and timers get added to the same idle cpu where the request was made. So the existing optimization works only on semi idle system). And In semi idle system, we no longer have periodic ticks on the idle load balancer CPU. Using that cpu will add more delays to the timers than intended (as that cpu's timer base may not be uptodate wrt jiffies etc). This was causing mysterious slowdowns during boot etc. For now, in the semi idle case, use the nearest busy cpu for migrating timers from an idle cpu. This is good for power-savings anyway. Signed-off-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <1274486981.2840.46.camel@sbs-t61.sc.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hrtimer: Avoid double seqlockStanislaw Gruszka2010-05-261-1/+1
| | | | | | | | | | | hrtimer_get_softirq_time() has it's own xtime lock protection, so it's safe to use plain __current_kernel_time() and avoid the double seqlock loop. Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl> LKML-Reference: <20100525214912.GA1934@r2bh72.net.upc.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* hrtimers: Provide schedule_hrtimeout for CLOCK_REALTIMECarsten Emde2010-04-061-26/+41
| | | | | | | | | | | | | | | | | | The current version of schedule_hrtimeout() always uses the monotonic clock. Some system calls such as mq_timedsend() and mq_timedreceive(), however, require the use of the wall clock due to the definition of the system call. This patch provides the infrastructure to use schedule_hrtimeout() with a CLOCK_REALTIME timer. Signed-off-by: Carsten Emde <C.Emde@osadl.org> Tested-by: Pradyumna Sampath <pradysam@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Veen <arjan@infradead.org> LKML-Reference: <20100402204331.167439615@osadl.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* hrtimers: Convert to raw_spinlocksThomas Gleixner2009-12-141-25/+25
| | | | | | | | | Convert locks which cannot be sleeping locks in preempt-rt to raw_spinlocks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Ingo Molnar <mingo@elte.hu>
* hrtimer: move timer stats helper functions to hrtimer.cHeiko Carstens2009-12-101-4/+20
| | | | | | | | | | | | There is no reason to make timer_stats_hrtimer_set_start_info and friends visible to the rest of the kernel. So move all of them to hrtimer.c. Also make timer_stats_hrtimer_set_start_info a static inline function so it gets inlined and we avoid another function call. Based on a patch by Thomas Gleixner. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> LKML-Reference: <20091210095629.GC4144@osiris.boeblingen.de.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* hrtimer: Tune hrtimer_interrupt hang logicThomas Gleixner2009-12-101-40/+57
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The hrtimer_interrupt hang logic adjusts min_delta_ns based on the execution time of the hrtimer callbacks. This is error-prone for virtual machines, where a guest vcpu can be scheduled out during the execution of the callbacks (and the callbacks themselves can do operations that translate to blocking operations in the hypervisor), which in can lead to large min_delta_ns rendering the system unusable. Replace the current heuristics with something more reliable. Allow the interrupt code to try 3 times to catch up with the lost time. If that fails use the total time spent in the interrupt handler to defer the next timer interrupt so the system can catch up with other things which got delayed. Limit that deferment to 100ms. The retry events and the maximum time spent in the interrupt handler are recorded and exposed via /proc/timer_list Inspired by a patch from Marcelo. Reported-by: Michael Tokarev <mjt@tls.msk.ru> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Marcelo Tosatti <mtosatti@redhat.com> Cc: kvm@vger.kernel.org
* Merge branch 'timers-for-linus' of ↵Linus Torvalds2009-12-081-1/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: Allow 32-bit machines to sleep for more than 2.15 secondsJon Hunter2009-11-131-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the dynamic tick code, "max_delta_ns" (member of the "clock_event_device" structure) represents the maximum sleep time that can occur between timer events in nanoseconds. The variable, "max_delta_ns", is defined as an unsigned long which is a 32-bit integer for 32-bit machines and a 64-bit integer for 64-bit machines (if -m64 option is used for gcc). The value of max_delta_ns is set by calling the function "clockevent_delta2ns()" which returns a maximum value of LONG_MAX. For a 32-bit machine LONG_MAX is equal to 0x7fffffff and in nanoseconds this equates to ~2.15 seconds. Hence, the maximum sleep time for a 32-bit machine is ~2.15 seconds, where as for a 64-bit machine it will be many years. This patch changes the type of max_delta_ns to be "u64" instead of "unsigned long" so that this variable is a 64-bit type for both 32-bit and 64-bit machines. It also changes the maximum value returned by clockevent_delta2ns() to KTIME_MAX. Hence this allows a 32-bit machine to sleep for longer than ~2.15 seconds. Please note that this patch also changes "min_delta_ns" to be "u64" too and although this is unnecessary, it makes the patch simpler as it avoids to fixup all callers of clockevent_delta2ns(). [ tglx: changed "unsigned long long" to u64 as we use this data type through out the time code ] Signed-off-by: Jon Hunter <jon-hunter@ti.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <1250617512-23567-3-git-send-email-jon-hunter@ti.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | Merge branch 'timers-fixes-for-linus' of ↵Linus Torvalds2009-10-051-2/+0
|\ \ | |/ |/| | | | | | | | | 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: hrtimer: Remove overly verbose "switch to high res mode" message
| * hrtimer: Remove overly verbose "switch to high res mode" messageRoland Dreier2009-09-261-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | On big systems, printing <number of CPUs> copies of Switched to high resolution mode on CPU nnn clutters up the kernel log for minimal gain. Just get rid of them. Signed-off-by: Roland Dreier <rolandd@cisco.com> LKML-Reference: <ada1vlw126s.fsf_-_@cisco.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | Merge branch 'timers-for-linus' of ↵Linus Torvalds2009-09-271-18/+35
|\ \ | |/ |/| | | | | | | | | 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: hrtimer: Eliminate needless reprogramming of clock events device
| * hrtimer: Eliminate needless reprogramming of clock events deviceAshwin Chaugule2009-09-151-18/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On NOHZ systems the following timers, - tick_nohz_restart_sched_tick (tick_sched_timer) - hrtimer_start (tick_sched_timer) are reprogramming the clock events device far more often than needed. No specific test case was required to observe this effect. This occurres because there was no check to see if the currently removed or restarted hrtimer was: 1) the one which previously armed the clock events device. 2) going to be replaced by another timer which has the same expiry time. Avoid the reprogramming in hrtimer_force_reprogram when the new expiry value which is evaluated from the clock bases is equal to cpu_base->expires_next. This results in faster application startup time by ~4%. [ tglx: simplified initial solution ] Signed-off-by: Ashwin Chaugule <ashwinc@quicinc.com> LKML-Reference: <4AA00165.90609@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | Merge branch 'timers-for-linus' of ↵Linus Torvalds2009-09-231-8/+32
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: itimers: Add tracepoints for itimer hrtimer: Add tracepoint for hrtimers timers: Add tracepoints for timer_list timers cputime: Optimize jiffies_to_cputime(1) itimers: Simplify arm_timer() code a bit itimers: Fix periodic tics precision itimers: Merge ITIMER_VIRT and ITIMER_PROF Trivial header file include conflicts in kernel/fork.c
| * | hrtimer: Add tracepoint for hrtimersXiao Guangrong2009-08-291-8/+32
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add tracepoints which cover the life cycle of a hrtimer. The tracepoints are integrated with the already existing debug_object debug points as far as possible. [ tglx: Fixed comments, made output conistent, easier to read and parse. Fixed output for 32bit archs which do not use the scalar representation of ktime_t. Hand current time to trace_hrtimer_expiry_entry instead of calling get_time() inside of the trace assignment. ] Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Anton Blanchard <anton@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Zhaolei <zhaolei@cn.fujitsu.com> LKML-Reference: <4A7F8B2B.5020908@cn.fujitsu.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | Merge branch 'timers-for-linus' of ↵Linus Torvalds2009-09-181-57/+0
|\ \ | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: (34 commits) time: Prevent 32 bit overflow with set_normalized_timespec() clocksource: Delay clocksource down rating to late boot clocksource: clocksource_select must be called with mutex locked clocksource: Resolve cpu hotplug dead lock with TSC unstable, fix crash timers: Drop a function prototype clocksource: Resolve cpu hotplug dead lock with TSC unstable timer.c: Fix S/390 comments timekeeping: Fix invalid getboottime() value timekeeping: Fix up read_persistent_clock() breakage on sh timekeeping: Increase granularity of read_persistent_clock(), build fix time: Introduce CLOCK_REALTIME_COARSE x86: Do not unregister PIT clocksource on PIT oneshot setup/shutdown clocksource: Avoid clocksource watchdog circular locking dependency clocksource: Protect the watchdog rating changes with clocksource_mutex clocksource: Call clocksource_change_rating() outside of watchdog_lock timekeeping: Introduce read_boot_clock timekeeping: Increase granularity of read_persistent_clock() timekeeping: Update clocksource with stop_machine timekeeping: Add timekeeper read_clock helper functions timekeeping: Move NTP adjusted clock multiplier to struct timekeeper ... Fix trivial conflict due to MIPS lemote -> loongson renaming.
| * Merge branch 'linus' into timers/coreThomas Gleixner2009-08-141-46/+64
| |\ | | | | | | | | | | | | | | | | | | Reason: Martin's timekeeping cleanup series depends on both timers/core and mainline changes. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | hrtimer: Remove cb_entry from struct hrtimerPeter Zijlstra2009-07-221-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | It's unused, remove it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> LKML-Reference: <new-submission>
| * | timekeeping: Move ktime_get() functions to timekeeping.cThomas Gleixner2009-07-071-60/+0
| | | | | | | | | | | | | | | | | | | | | | | | The ktime_get() functions for GENERIC_TIME=n are still located in hrtimer.c. Move them to time/timekeeping.c where they belong. LKML-Reference: <new-submission> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| * | timekeeping: optimized ktime_get[_ts] for GENERIC_TIME=yMartin Schwidefsky2009-07-071-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The generic ktime_get function defined in kernel/hrtimer.c is suboptimial for GENERIC_TIME=y: 0) | ktime_get() { 0) | ktime_get_ts() { 0) | getnstimeofday() { 0) | read_tod_clock() { 0) 0.601 us | } 0) 1.938 us | } 0) | set_normalized_timespec() { 0) 0.602 us | } 0) 4.375 us | } 0) 5.523 us | } Overall there are two read_seqbegin/read_seqretry loops and a lot of unnecessary struct timespec calculations. ktime_get returns a nano second value which is the sum of xtime, wall_to_monotonic and the nano second delta from the clock source. ktime_get can be optimized for GENERIC_TIME=y. The new version only calls clocksource_read: 0) | ktime_get() { 0) | read_tod_clock() { 0) 0.610 us | } 0) 1.977 us | } It uses a single read_seqbegin/readseqretry loop and just adds everthing to a nano second value. ktime_get_ts is optimized in a similar fashion. [ tglx: added WARN_ON(timekeeping_suspended) as in getnstimeofday() ] Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Acked-by: john stultz <johnstul@us.ibm.com> LKML-Reference: <20090707112728.3005244d@skybase> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | | pktgen: spin using hrtimerStephen Hemminger2009-08-281-0/+2
| |/ |/| | | | | | | | | | | | | | | This changes how the pktgen thread spins/waits between packets if delay is configured. It uses a high res timer to wait for time to arrive. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | hrtimer: Fix migration expiry checkThomas Gleixner2009-07-101-57/+64
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The timer migration expiry check should prevent the migration of a timer to another CPU when the timer expires before the next event is scheduled on the other CPU. Migrating the timer might delay it because we can not reprogram the clock event device on the other CPU. But the code implementing that check has two flaws: - for !HIGHRES the check compares the expiry value with the clock events device expiry value which is wrong for CLOCK_REALTIME based timers. - the check is racy. It holds the hrtimer base lock of the target CPU, but the clock event device expiry value can be modified nevertheless, e.g. by an timer interrupt firing. The !HIGHRES case is easy to fix as we can enqueue the timer on the cpu which was selected by the load balancer. It runs the idle balancing code once per jiffy anyway. So the maximum delay for the timer is the same as when we keep the tick on the current cpu going. In the HIGHRES case we can get the next expiry value from the hrtimer cpu_base of the target CPU and serialize the update with the cpu_base lock. This moves the lock section in hrtimer_interrupt() so we can set next_event to KTIME_MAX while we are handling the expired timers and set it to the next expiry value after we handled the timers under the base lock. While the expired timers are processed timer migration is blocked because the expiry time of the timer is always <= KTIME_MAX. Also remove the now useless clockevents_get_next_event() function. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* | hrtimer: migration: do not check expiry time on current CPUThomas Gleixner2009-07-101-2/+13
|/ | | | | | | | | | | | | | | | | | | | | | | The timer migration code needs to check whether the expiry time of the timer is before the programmed clock event expiry time when the timer is enqueued on another CPU because we can not reprogram the timer device on the other CPU. The current logic checks the expiry time even if we enqueue on the current CPU when nohz_get_load_balancer() returns current CPU. This might lead to an endless loop in the expiry check code when the expiry time of the timer is before the current programmed next event. Check whether nohz_get_load_balancer() returns current CPU and skip the expiry check if this is the case. The bug was triggered from the networking code. The patch fixes the regression http://bugzilla.kernel.org/show_bug.cgi?id=13738 (Soft-Lockup/Race in networking in 2.6.31-rc1+195) Cc: Arun Bharadwaj <arun@linux.vnet.ibm.com Tested-by: Joao Correia <joaomiguelcorreia@gmail.com> Tested-by: Andres Freund <andres@anarazel.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'linux-next' of git://git.infradead.org/ubifs-2.6Linus Torvalds2009-06-171-0/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | * 'linux-next' of git://git.infradead.org/ubifs-2.6: UBIFS: start using hrtimers hrtimer: export ktime_add_safe UBIFS: do not forget to register BDI device UBIFS: allow sync option in rootflags UBIFS: remove dead code UBIFS: use anonymous device UBIFS: return proper error code if the compr is not present UBIFS: return error if link and unlink race UBIFS: reset no_space flag after inode deletion
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