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2015-06-19timer: Minimize nohz off overheadThomas Gleixner1-0/+2
If nohz is disabled on the kernel command line the [hr]timer code still calls wake_up_nohz_cpu() and tick_nohz_full_cpu(), a pretty pointless exercise. Cache nohz_active in [hr]timer per cpu bases and avoid the overhead. Before: 48.10% hog [.] main 15.25% [kernel] [k] _raw_spin_lock_irqsave 9.76% [kernel] [k] _raw_spin_unlock_irqrestore 6.50% [kernel] [k] mod_timer 6.44% [kernel] [k] lock_timer_base.isra.38 3.87% [kernel] [k] detach_if_pending 3.80% [kernel] [k] del_timer 2.67% [kernel] [k] internal_add_timer 1.33% [kernel] [k] __internal_add_timer 0.73% [kernel] [k] timerfn 0.54% [kernel] [k] wake_up_nohz_cpu After: 48.73% hog [.] main 15.36% [kernel] [k] _raw_spin_lock_irqsave 9.77% [kernel] [k] _raw_spin_unlock_irqrestore 6.61% [kernel] [k] lock_timer_base.isra.38 6.42% [kernel] [k] mod_timer 3.90% [kernel] [k] detach_if_pending 3.76% [kernel] [k] del_timer 2.41% [kernel] [k] internal_add_timer 1.39% [kernel] [k] __internal_add_timer 0.76% [kernel] [k] timerfn We probably should have a cached value for nohz full in the per cpu bases as well to avoid the cpumask check. The base cache line is hot already, the cpumask not necessarily. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Joonwoo Park <joonwoop@codeaurora.org> Cc: Wenbo Wang <wenbo.wang@memblaze.com> Link: http://lkml.kernel.org/r/20150526224512.207378134@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-19timer: Reduce timer migration overhead if disabledThomas Gleixner1-0/+2
Eric reported that the timer_migration sysctl is not really nice performance wise as it needs to check at every timer insertion whether the feature is enabled or not. Further the check does not live in the timer code, so we have an extra function call which checks an extra cache line to figure out that it is disabled. We can do better and store that information in the per cpu (hr)timer bases. I pondered to use a static key, but that's a nightmare to update from the nohz code and the timer base cache line is hot anyway when we select a timer base. The old logic enabled the timer migration unconditionally if CONFIG_NO_HZ was set even if nohz was disabled on the kernel command line. With this modification, we start off with migration disabled. The user visible sysctl is still set to enabled. If the kernel switches to NOHZ migration is enabled, if the user did not disable it via the sysctl prior to the switch. If nohz=off is on the kernel command line, migration stays disabled no matter what. Before: 47.76% hog [.] main 14.84% [kernel] [k] _raw_spin_lock_irqsave 9.55% [kernel] [k] _raw_spin_unlock_irqrestore 6.71% [kernel] [k] mod_timer 6.24% [kernel] [k] lock_timer_base.isra.38 3.76% [kernel] [k] detach_if_pending 3.71% [kernel] [k] del_timer 2.50% [kernel] [k] internal_add_timer 1.51% [kernel] [k] get_nohz_timer_target 1.28% [kernel] [k] __internal_add_timer 0.78% [kernel] [k] timerfn 0.48% [kernel] [k] wake_up_nohz_cpu After: 48.10% hog [.] main 15.25% [kernel] [k] _raw_spin_lock_irqsave 9.76% [kernel] [k] _raw_spin_unlock_irqrestore 6.50% [kernel] [k] mod_timer 6.44% [kernel] [k] lock_timer_base.isra.38 3.87% [kernel] [k] detach_if_pending 3.80% [kernel] [k] del_timer 2.67% [kernel] [k] internal_add_timer 1.33% [kernel] [k] __internal_add_timer 0.73% [kernel] [k] timerfn 0.54% [kernel] [k] wake_up_nohz_cpu Reported-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Joonwoo Park <joonwoop@codeaurora.org> Cc: Wenbo Wang <wenbo.wang@memblaze.com> Link: http://lkml.kernel.org/r/20150526224512.127050787@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-19hrtimer: Allow hrtimer::function() to free the timerPeter Zijlstra1-25/+16
Currently an hrtimer callback function cannot free its own timer because __run_hrtimer() still needs to clear HRTIMER_STATE_CALLBACK after it. Freeing the timer would result in a clear use-after-free. Solve this by using a scheme similar to regular timers; track the current running timer in hrtimer_clock_base::running. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: ktkhai@parallels.com Cc: rostedt@goodmis.org Cc: juri.lelli@gmail.com Cc: pang.xunlei@linaro.org Cc: wanpeng.li@linux.intel.com Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: umgwanakikbuti@gmail.com Link: http://lkml.kernel.org/r/20150611124743.471563047@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-19hrtimer: Remove HRTIMER_STATE_MIGRATEOleg Nesterov1-5/+1
I do not understand HRTIMER_STATE_MIGRATE. Unless I am totally confused it looks buggy and simply unneeded. migrate_hrtimer_list() sets it to keep hrtimer_active() == T, but this is not enough: this can fool, say, hrtimer_is_queued() in dequeue_signal(). Can't migrate_hrtimer_list() simply use HRTIMER_STATE_ENQUEUED? This fixes the race and we can kill STATE_MIGRATE. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: ktkhai@parallels.com Cc: rostedt@goodmis.org Cc: juri.lelli@gmail.com Cc: pang.xunlei@linaro.org Cc: wanpeng.li@linux.intel.com Cc: umgwanakikbuti@gmail.com Link: http://lkml.kernel.org/r/20150611124743.072387650@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-06-08hrtimers: Make sure hrtimer_resolution is unsigned intBorislav Petkov1-1/+1
... in the !CONFIG_HIGH_RES_TIMERS case too. And thus fix warnings like this one: net/sched/sch_api.c: In function ‘psched_show’: net/sched/sch_api.c:1891:6: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 6 has type ‘long int’ [-Wformat=] (u32)NSEC_PER_SEC / hrtimer_resolution); Signed-off-by: Borislav Petkov <bp@suse.de> Link: http://lkml.kernel.org/r/1433583000-32090-1-git-send-email-bp@alien8.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Remove hrtimer_start() return valueThomas Gleixner1-13/+9
No user was ever interested whether the timer was active or not when it was started. All abusers of the return value are gone, so get rid of it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203503.483556394@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Make hrtimer_start() a inline wrapperThomas Gleixner1-2/+17
No point for an extra export just to set the extra argument of hrtimer_start_range_ns() to 0. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203502.808544539@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Get rid of __hrtimer_start_range_ns()Thomas Gleixner1-4/+0
No more callers. Remove the leftovers. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203502.707871492@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22tick: Nohz: Rework next timer evaluationThomas Gleixner1-1/+1
The evaluation of the next timer in the nohz code is based on jiffies while all the tick internals are nano seconds based. We have also to convert hrtimer nanoseconds to jiffies in the !highres case. That's just wrong and introduces interesting corner cases. Turn it around and convert the next timer wheel timer expiry and the rcu event to clock monotonic and base all calculations on nanoseconds. That identifies the case where no timer is pending clearly with an absolute expiry value of KTIME_MAX. Makes the code more readable and gets rid of the jiffies magic in the nohz code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Link: http://lkml.kernel.org/r/20150414203502.184198593@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Get rid of hrtimer softirqThomas Gleixner1-1/+0
hrtimer softirq is a leftover from the initial implementation and serves only the purpose to handle the enqueueing of already expired timers in the high resolution timer mode. We discussed whether we change the return value and force all start sites to handle that the timer is already expired, but that would be a Herculean task and I'm not sure whether its a good idea to enforce that handling on everyone. A simpler solution is to enforce a timer interrupt instead of raising and scheduling a softirq. Just use the existing infrastructure to do so and remove all the softirq leftovers. The HRTIMER softirq enum is now unused, but kept around because trace parsers rely on the existing numbering. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203501.840834708@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Keep pointer to first timer and simplify __remove_hrtimer()Thomas Gleixner1-0/+6
__remove_hrtimer() needs to evaluate the expiry time to figure out whether the timer which is removed is eventually the first expiring timer on the cpu. Keep a pointer to it, which is lazily updated, so we can avoid the evaluation dance and retrieve the information from there. Generates slightly better code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203501.752838019@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Align the hrtimer clock bases as wellThomas Gleixner1-1/+9
We don't use cacheline_align here because that might waste lot of space on 32bit machine with 64 bytes cachelines and on 64bit machines with 128 bytes cachelines. The size of struct hrtimer_clock_base is 64byte on 64bit and 32byte on 32bit machines. So we utilize the cache lines proper. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203501.498165771@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Cache line align the hrtimer cpu baseThomas Gleixner1-1/+1
We really want that data structure to start at a cache line boundary. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203501.417597627@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Use bits for various boolean indicatorsThomas Gleixner1-3/+3
No point in wasting 12 byte storage space. Generates better code as well. Text size reduction: x8664 -64, i386 -16, ARM -132, ARM64 -0, power64 -48 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203501.227955358@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Make offset update smarterThomas Gleixner1-2/+2
On every tick/hrtimer interrupt we update the offset variables of the clock bases. That's silly because these offsets change very seldom. Add a sequence counter to the time keeping code which keeps track of the offset updates (clock_was_set()). Have a sequence cache in the hrtimer cpu bases to evaluate whether the offsets must be updated or not. This allows us later to avoid pointless cacheline pollution. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: John Stultz <john.stultz@linaro.org> Link: http://lkml.kernel.org/r/20150414203501.132820245@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org>
2015-04-22hrtimer: Get rid of softirq timeThomas Gleixner1-19/+5
The softirq time field in the clock bases is an optimization from the early days of hrtimers. It provides a coarse "jiffies" like time mostly for self rearming timers. But that comes with a price: - Larger code size - Extra storage space - Duplicated functions with really small differences The benefit of this is optimization is marginal for contemporary systems. Consolidate everything on the high resolution timer implementation. This makes further optimizations possible. Text size reduction: x8664 -95, i386 -356, ARM -148, ARM64 -40, power64 -16 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203501.039977424@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Make the statistics fields smallerThomas Gleixner1-4/+4
No point in having usigned long for /proc/timer_list statistics. Make them unsigned int. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203500.959773467@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Get rid of hrtimer_get_res()Thomas Gleixner1-1/+0
The resolution is directly accessible now. So its simpler just to fill in the values of the timespec and be done with it. Text size reduction (combined with "hrtimer: Get rid of the resolution field in hrtimer_clock_base"): x8664 -61, i386 -221, ARM -60, power64 -48 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203500.879888080@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Get rid of the resolution field in hrtimer_clock_baseThomas Gleixner1-2/+4
The field has no value because all clock bases have the same resolution. The resolution only changes when we switch to high resolution timer mode. We can evaluate that from a single static variable as well. In the !HIGHRES case its simply a constant. Export the variable, so we can simplify the usage sites. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20150414203500.645454122@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-04-22hrtimer: Document hrtimer_forward[_now]() properThomas Gleixner1-1/+16
Document the calling context conditions. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20150413210035.178751779@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-01-23hrtimer: Prevent stale expiry time in hrtimer_interrupt()Thomas Gleixner1-0/+2
hrtimer_interrupt() has the following subtle issue: hrtimer_interrupt() lock(cpu_base); expires_next = KTIME_MAX; expire_timers(CLOCK_MONOTONIC); expires = get_next_timer(CLOCK_MONOTONIC); if (expires < expires_next) expires_next = expires; expire_timers(CLOCK_REALTIME); unlock(cpu_base); wakeup() hrtimer_start(CLOCK_MONOTONIC, newtimer); lock(cpu_base(); expires = get_next_timer(CLOCK_REALTIME); if (expires < expires_next) expires_next = expires; So because we already evaluated the next expiring timer of CLOCK_MONOTONIC we ignore that the expiry time of newtimer might be earlier than the overall next expiry time in hrtimer_interrupt(). To solve this, remove the caching of the next expiry value from hrtimer_interrupt() and reevaluate all active clock bases for the next expiry value. To avoid another code duplication, create a shared evaluation function and use it for hrtimer_get_next_event(), hrtimer_force_reprogram() and hrtimer_interrupt(). There is another subtlety in this mechanism: While hrtimer_interrupt() is running, we want to avoid to touch the hardware device because we will reprogram it anyway at the end of hrtimer_interrupt(). This works nicely for hrtimers which get rearmed via the HRTIMER_RESTART mechanism, because we drop out when the callback on that CPU is running. But that fails, if a new timer gets enqueued like in the example above. This has another implication: While hrtimer_interrupt() is running we refuse remote enqueueing of timers - see hrtimer_interrupt() and hrtimer_check_target(). hrtimer_interrupt() tries to prevent this by setting cpu_base->expires to KTIME_MAX, but that fails if a new timer gets queued. Prevent both the hardware access and the remote enqueue explicitely. We can loosen the restriction on the remote enqueue now due to reevaluation of the next expiry value, but that needs a seperate patch. Folded in a fix from Vignesh Radhakrishnan. Reported-and-tested-by: Stanislav Fomichev <stfomichev@yandex-team.ru> Based-on-patch-by: Stanislav Fomichev <stfomichev@yandex-team.ru> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: vigneshr@codeaurora.org Cc: john.stultz@linaro.org Cc: viresh.kumar@linaro.org Cc: fweisbec@gmail.com Cc: cl@linux.com Cc: stuart.w.hayes@gmail.com Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1501202049190.5526@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-07-23time: Consolidate the time accessor prototypesThomas Gleixner1-11/+0
Right now we have time related prototypes in 3 different header files. Move it to a single timekeeping header file and move the core internal stuff into a core private header. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23ktime: Sanitize ktime_to_us/ms conversionThomas Gleixner1-6/+0
With the plain nanoseconds based ktime_t we can simply use ktime_divns() instead of going through loops and hoops of timespec/timeval conversion. Reported-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23hrtimer: Cleanup hrtimer accessors to the timekepeing stateJohn Stultz1-3/+6
Rather then having two similar but totally different implementations that provide timekeeping state to the hrtimer code, try to unify the two implementations to be more simliar. Thus this clarifies ktime_get_update_offsets to ktime_get_update_offsets_now and changes get_xtime... to ktime_get_update_offsets_tick. Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-06-23hrtimer: Store cpu-number in struct hrtimer_cpu_baseViresh Kumar1-0/+2
In lowres mode, hrtimers are serviced by the tick instead of a clock event. Now it works well as long as the tick stays periodic but we must also make sure that the hrtimers are serviced in dynticks mode. Part of that job consist in kicking a dynticks hrtimer target in order to make it reconsider the next tick to schedule to correctly handle the hrtimer's expiring time. And that part isn't handled by the hrtimers subsystem. To prepare for fixing this, we need __hrtimer_start_range_ns() to be able to resolve the CPU target associated to a hrtimer's object 'cpu_base' so that the kick can be centralized there. So lets store it in the 'struct hrtimer_cpu_base' to resolve the CPU without overhead. It is set once at CPU's online notification. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1403393357-2070-4-git-send-email-fweisbec@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-03-20hrtimer: Rearrange comments in the order struct members are declaredViresh Kumar1-2/+2
Rearrange kernel doc comments in the order members of struct hrtimer are declared. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: linaro-kernel@lists.linaro.org Cc: fweisbec@gmail.com Cc: trivial@kernel.org Link: http://lkml.kernel.org/r/1db1a3cfbe8a9ea49396af75c6ac04a2e67e3ab0.1395226248.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-03-23hrtimer: Add hrtimer support for CLOCK_TAIJohn Stultz1-1/+4
Add hrtimer support for CLOCK_TAI, as well as posix timer interfaces. Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-07-12timekeeping: Provide hrtimer update functionThomas Gleixner1-0/+1
To finally fix the infamous leap second issue and other race windows caused by functions which change the offsets between the various time bases (CLOCK_MONOTONIC, CLOCK_REALTIME and CLOCK_BOOTTIME) we need a function which atomically gets the current monotonic time and updates the offsets of CLOCK_REALTIME and CLOCK_BOOTTIME with minimalistic overhead. The previous patch which provides ktime_t offsets allows us to make this function almost as cheap as ktime_get() which is going to be replaced in hrtimer_interrupt(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Prarit Bhargava <prarit@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: John Stultz <johnstul@us.ibm.com> Link: http://lkml.kernel.org/r/1341960205-56738-7-git-send-email-johnstul@us.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-07-12hrtimer: Provide clock_was_set_delayed()John Stultz1-1/+8
clock_was_set() cannot be called from hard interrupt context because it calls on_each_cpu(). For fixing the widely reported leap seconds issue it is necessary to call it from hard interrupt context, i.e. the timer tick code, which does the timekeeping updates. Provide a new function which denotes it in the hrtimer cpu base structure of the cpu on which it is called and raise the hrtimer softirq. We then execute the clock_was_set() notificiation from softirq context in run_hrtimer_softirq(). The hrtimer softirq is rarely used, so polling the flag there is not a performance issue. [ tglx: Made it depend on CONFIG_HIGH_RES_TIMERS. We really should get rid of all this ifdeffery ASAP ] Signed-off-by: John Stultz <johnstul@us.ibm.com> Reported-by: Jan Engelhardt <jengelh@inai.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Prarit Bhargava <prarit@redhat.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1341960205-56738-2-git-send-email-johnstul@us.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-06-28Fix some kernel-doc warningsVitaliy Ivanov1-0/+1
Fix 'make htmldocs' warnings: Warning(/include/linux/hrtimer.h:153): No description found for parameter 'clockid' Warning(/include/linux/device.h:604): Excess struct/union/enum/typedef member 'of_match' description in 'device' Warning(/include/net/sock.h:349): Excess struct/union/enum/typedef member 'sk_rmem_alloc' description in 'sock' Signed-off-by: Vitaliy Ivanov <vitalivanov@gmail.com> Acked-by: Grant Likely <grant.likely@secretlab.ca> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-23hrtimers: Reorder clock basesThomas Gleixner1-1/+1
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>
2011-05-23hrtimers: Avoid touching inactive timer basesThomas Gleixner1-2/+5
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>
2011-05-23hrtimers: Make struct hrtimer_cpu_base layout less stupidThomas Gleixner1-1/+1
In the HIGHRES=y case we access the members at the end of struct hrtimer_cpu_base first and then the one at the beginning. Move the hrtimer data to front, so we have linear progressing access. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Peter Zijlstra <peterz@infradead.org>
2011-05-23timerfd: Manage cancelable timers in timerfdThomas Gleixner1-1/+5
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>
2011-05-02timerfd: Allow timers to be cancelled when clock was setThomas Gleixner1-0/+2
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>
2011-05-02hrtimers: Prepare for cancel on clock was set timersThomas Gleixner1-13/+3
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>
2011-03-10hrtimer: Update hrtimer->state documentationThomas Gleixner1-5/+11
We changed some of the state bits and combinations thereof over time, but never updated the documentation. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-02-21timers: Add CLOCK_BOOTTIME hrtimer baseJohn Stultz1-0/+1
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>
2011-02-21time: Introduce get_monotonic_boottime and ktime_get_boottimeJohn Stultz1-0/+1
This adds new functions that return the monotonic time since boot (in other words, CLOCK_MONOTONIC + suspend time). 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>
2011-02-21hrtimers: extend hrtimer base code to handle more then 2 clockidsJohn Stultz1-1/+5
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>
2011-01-10hrtimer.h: fix kernel-doc warningRandy Dunlap1-1/+0
Fix new kernel-doc notation warning in hrtimer.h: Warning(include/linux/hrtimer.h:150): Excess struct/union/enum/typedef member 'first' description in 'hrtimer_clock_base' Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-12-10hrtimers: Convert hrtimers to use timerlist infrastructureJohn Stultz1-17/+15
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>
2010-11-10hrtimer: Remove stale comment on curr_timerYong Zhang1-1/+0
curr_timer doesn't resident in struct hrtimer_cpu_base anymore. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> LKML-Reference: <1287892253-2587-1-git-send-email-yong.zhang0@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-04-06hrtimers: Provide schedule_hrtimeout for CLOCK_REALTIMECarsten Emde1-0/+2
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>
2009-12-15hrtimers: Convert to raw_spinlocksThomas Gleixner1-1/+1
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>
2009-12-10hrtimer: move timer stats helper functions to hrtimer.cHeiko Carstens1-43/+0
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>
2009-12-10hrtimer: Tune hrtimer_interrupt hang logicThomas Gleixner1-4/+9
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
2009-11-20hrtimer: Fix /proc/timer_list regressionFeng Tang1-3/+1
commit 507e1231 (timer stats: Optimize by adding quick check to avoid function calls) introduced a regression in /proc/timer_list. /proc/timer_list shows now #0: <c27d46b0>, tick_sched_timer, S:01, <(null)>, /-1 instead of #0: <c27d46b0>, tick_sched_timer, S:01, hrtimer_start, swapper/0 Revert the hrtimer quick check for now. The optimization needs more thought, but this is neither 2.6.32-rc7 nor stable material. [ tglx: - Removed unrelated changes from the original patch - Prevent unneccesary call to timer_stats_update_stats - massaged the changelog ] Signed-off-by: Feng Tang <feng.tang@intel.com> LKML-Reference: <alpine.LFD.2.00.0911181933540.24119@localhost.localdomain> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: stable@kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-14Merge branch 'linus' into timers/coreThomas Gleixner1-1/+1
Reason: Martin's timekeeping cleanup series depends on both timers/core and mainline changes. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-07-22hrtimer: Remove cb_entry from struct hrtimerPeter Zijlstra1-2/+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>
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