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2014-07-23timekeeping: Use cached ntp_tick_length when accumulating errorJohn Stultz
By caching the ntp_tick_length() when we correct the frequency error, and then using that cached value to accumulate error, we avoid large initial errors when the tick length is changed. This makes convergence happen much faster in the simulator, since the initial error doesn't have to be slowly whittled away. This initially seems like an accounting error, but Miroslav pointed out that ntp_tick_length() can change mid-tick, so when we apply it in the error accumulation, we are applying any recent change to the entire tick. This approach chooses to apply changes in the ntp_tick_length() only to the next tick, which allows us to calculate the freq correction before using the new tick length, which avoids accummulating error. Credit to Miroslav for pointing this out and providing the original patch this functionality has been pulled out from, along with the rational. Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Reported-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Rework frequency adjustments to work better w/ nohzJohn Stultz
The existing timekeeping_adjust logic has always been complicated to understand. Further, since it was developed prior to NOHZ becoming common, its not surprising it performs poorly when NOHZ is enabled. Since Miroslav pointed out the problematic nature of the existing code in the NOHZ case, I've tried to refactor the code to perform better. The problem with the previous approach was that it tried to adjust for the total cumulative error using a scaled dampening factor. This resulted in large errors to be corrected slowly, while small errors were corrected quickly. With NOHZ the timekeeping code doesn't know how far out the next tick will be, so this results in bad over-correction to small errors, and insufficient correction to large errors. Inspired by Miroslav's patch, I've refactored the code to try to address the correction in two steps. 1) Check the future freq error for the next tick, and if the frequency error is large, try to make sure we correct it so it doesn't cause much accumulated error. 2) Then make a small single unit adjustment to correct any cumulative error that has collected over time. This method performs fairly well in the simulator Miroslav created. Major credit to Miroslav for pointing out the issue, providing the original patch to resolve this, a simulator for testing, as well as helping debug and resolve issues in my implementation so that it performed closer to his original implementation. Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Reported-by: Miroslav Lichvar <mlichvar@redhat.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Minor fixup for timespec64->timespec assignmentJohn Stultz
In the GENERIC_TIME_VSYSCALL_OLD update_vsyscall implementation, we take the tk_xtime() value, which returns a timespec64, and store it in a timespec. This luckily is ok, since the only architectures that use GENERIC_TIME_VSYSCALL_OLD are ia64 and ppc64, which are both 64 bit systems where timespec64 is the same as a timespec. Even so, for cleanliness reasons, use the conversion function to assign the proper type. Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide fast and NMI safe access to CLOCK_MONOTONICThomas Gleixner
Tracers want a correlated time between the kernel instrumentation and user space. We really do not want to export sched_clock() to user space, so we need to provide something sensible for this. Using separate data structures with an non blocking sequence count based update mechanism allows us to do that. The data structure required for the readout has a sequence counter and two copies of the timekeeping data. On the update side: smp_wmb(); tkf->seq++; smp_wmb(); update(tkf->base[0], tk); smp_wmb(); tkf->seq++; smp_wmb(); update(tkf->base[1], tk); On the reader side: do { seq = tkf->seq; smp_rmb(); idx = seq & 0x01; now = now(tkf->base[idx]); smp_rmb(); } while (seq != tkf->seq) So if a NMI hits the update of base[0] it will use base[1] which is still consistent, but this timestamp is not guaranteed to be monotonic across an update. The timestamp is calculated by: now = base_mono + clock_delta * slope So if the update lowers the slope, readers who are forced to the not yet updated second array are still using the old steeper slope. tmono ^ | o n | o n | u | o |o |12345678---> reader order o = old slope u = update n = new slope So reader 6 will observe time going backwards versus reader 5. While other CPUs are likely to be able observe that, the only way for a CPU local observation is when an NMI hits in the middle of the update. Timestamps taken from that NMI context might be ahead of the following timestamps. Callers need to be aware of that and deal with it. V2: Got rid of clock monotonic raw and reorganized the data structures. Folded in the barrier fix from Mathieu. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use tk_read_base as argument for timekeeping_get_ns()Thomas Gleixner
All the function needs is in the tk_read_base struct. No functional change for the current code, just a preparatory patch for the NMI safe accessor to clock monotonic which will use struct tk_read_base as well. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Create struct tk_read_base and use it in struct timekeeperThomas Gleixner
The members of the new struct are the required ones for the new NMI safe accessor to clcok monotonic. In order to reuse the existing timekeeping code and to make the update of the fast NMI safe timekeepers a simple memcpy use the struct for the timekeeper as well and convert all users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Restructure the timekeeper some moreThomas Gleixner
Access to time requires to touch two cachelines at minimum 1) The timekeeper data structure 2) The clocksource data structure The access to the clocksource data structure can be avoided as almost all clocksource implementations ignore the argument to the read callback, which is a pointer to the clocksource. But the core needs to touch it to access the members @read and @mask. So we are better off by copying the @read function pointer and the @mask from the clocksource to the core data structure itself. For the most used ktime_get() access all required data including the @read and @mask copies fits together with the sequence counter into a single 64 byte cacheline. For the other time access functions we touch in the current code three cache lines in the worst case. But with the clocksource data copies we can reduce that to two adjacent cachelines, which is more efficient than disjunct cache lines. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23clocksource: Get rid of cycle_lastThomas Gleixner
cycle_last was added to the clocksource to support the TSC validation. We moved that to the core code, so we can get rid of the extra copy. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23clocksource: Move cycle_last validation to core codeThomas Gleixner
The only user of the cycle_last validation is the x86 TSC. In order to provide NMI safe accessor functions for clock monotonic and monotonic_raw we need to do that in the core. We can't do the TSC specific if (now < cycle_last) now = cycle_last; for the other wrapping around clocksources, but TSC has CLOCKSOURCE_MASK(64) which actually does not mask out anything so if now is less than cycle_last the subtraction will give a negative result. So we can check for that in clocksource_delta() and return 0 for that case. Implement and enable it for x86 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23clocksource: Make delta calculation a functionThomas Gleixner
We want to move the TSC sanity check into core code to make NMI safe accessors to clock monotonic[_raw] possible. For this we need to sanity check the delta calculation. Create a helper function and convert all sites to use it. [ Build fix from jstultz ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide ktime_get_raw()Thomas Gleixner
Provide a ktime_t based interface for raw monotonic time. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Simplify timekeeping_clocktai()Thomas Gleixner
timekeeping_clocktai() is not used in fast pathes, so the extra timespec conversion is not problematic. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Remove timekeeper.total_sleep_timeThomas Gleixner
No more users. Remove it Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Simplify getboottime()Thomas Gleixner
Subtracting plain nsec values and converting to timespec is simpler than the whole timespec math. Not really fastpath code, so the division is not an issue. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_get_boottime() for get_monotonic_boottime()Thomas Gleixner
get_monotonic_boottime() is not used in fast pathes, so the extra timespec conversion is not problematic. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Remove monotonic_to_bootbasedThomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23time: Export nsecs_to_jiffies()Thomas Gleixner
Required for moving drivers to the nanosecond based interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Remove ktime_get_monotonic_offset()Thomas Gleixner
No more users. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide ktime_mono_to_any()Thomas Gleixner
ktime based conversion function to map a monotonic time stamp to a different CLOCK. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping; Use ktime based data for ktime_get_update_offsets_tick()Thomas Gleixner
No need to juggle with timespecs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_t data for ktime_get_update_offsets_now()Thomas Gleixner
No need to juggle with timespecs. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_t based data for ktime_get_clocktai()Thomas Gleixner
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping; Use ktime_t based data for ktime_get_boottime()Thomas Gleixner
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_t based data for ktime_get_real()Thomas Gleixner
Speed up the readout. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide ktime_get_with_offset()Thomas Gleixner
Provide a helper function which lets us implement ktime_t based interfaces for real, boot and tai clocks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use ktime_t based data for ktime_get()Thomas Gleixner
Speed up ktime_get() by using ktime_t based data. Text size shrinks by 64 bytes on x8664. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide internal ktime_t based dataThomas Gleixner
The ktime_t based interfaces are used a lot in performance critical code pathes. Add ktime_t based data so the interfaces don't have to convert from the xtime/timespec based data. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Use timekeeping_update() instead of memcpy()Thomas Gleixner
We already have a function which does the right thing, that also makes sure that the coming ktime_t based cached values are getting updated. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Cache optimize struct timekeeperThomas Gleixner
struct timekeeper is quite badly sorted for the hot readout path. Most time access functions need to load two cache lines. Rearrange it so ktime_get() and getnstimeofday() are happy with a single cache line. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeper: Move tk_xtime to core codeThomas Gleixner
No users outside of the core. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23timekeeping: Provide timespec64 based interfacesThomas Gleixner
To convert callers of the core code to timespec64 we need to provide the proper interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23time: Consolidate the time accessor prototypesThomas Gleixner
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>
2014-07-23timekeeping: Convert timekeeping core to use timespec64sJohn Stultz
Convert the core timekeeping logic to use timespec64s. This moves the 2038 issues out of the core logic and into all of the accessor functions. Future changes will need to push the timespec64s out to all timekeeping users, but that can be done interface by interface. 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>
2014-07-23time: More core infrastructure for timespec64John Stultz
Helper and conversion functions for timespec64. 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>
2014-07-23ktime: Sanitize ktime_to_us/ms conversionThomas Gleixner
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>
2014-07-23ktime: Kill non-scalar ktime_t implementation for 2038John Stultz
The non-scalar ktime_t implementation is basically a timespec which has to be changed to support dates past 2038 on 32bit systems. This patch removes the non-scalar ktime_t implementation, forcing the scalar s64 nanosecond version on all architectures. This may have additional performance overhead on some 32bit systems when converting between ktime_t and timespec structures, however the majority of 32bit systems (arm and i386) were already using scalar ktime_t, so no performance regressions will be seen on those platforms. On affected platforms, I'm open to finding optimizations, including avoiding converting to timespecs where possible. [ tglx: We can now cleanup the ktime_t.tv64 mess, but thats a different issue and we can throw a coccinelle script at it ] 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>
2014-07-23hrtimer: Cleanup hrtimer accessors to the timekepeing stateJohn Stultz
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>
2014-07-23timekeeping: Simplify arch_gettimeoffset()Thomas Gleixner
Provide a default stub function instead of having the extra conditional. Cuts binary size on a m68k build by ~100 bytes. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-23kernel: time: Add udelay_test module to validate udelayDavid Riley
Create a module that allows udelay() to be executed to ensure that it is delaying at least as long as requested (with a little bit of error allowed). There are some configurations which don't have reliably udelay due to using a loop delay with cpufreq changes which should use a counter time based delay instead. This test aims to identify those configurations where timing is unreliable. Signed-off-by: David Riley <davidriley@chromium.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-09rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUsPaul E. McKenney
Binding the grace-period kthreads to the timekeeping CPU resulted in significant performance decreases for some workloads. For more detail, see: https://lkml.org/lkml/2014/6/3/395 for benchmark numbers https://lkml.org/lkml/2014/6/4/218 for CPU statistics It turns out that it is necessary to bind the grace-period kthreads to the timekeeping CPU only when all but CPU 0 is a nohz_full CPU on the one hand or if CONFIG_NO_HZ_FULL_SYSIDLE=y on the other. In other cases, it suffices to bind the grace-period kthreads to the set of non-nohz_full CPUs. This commit therefore creates a tick_nohz_not_full_mask that is the complement of tick_nohz_full_mask, and then binds the grace-period kthread to the set of CPUs indicated by this new mask, which covers the CONFIG_NO_HZ_FULL_SYSIDLE=n case. The CONFIG_NO_HZ_FULL_SYSIDLE=y case still binds the grace-period kthreads to the timekeeping CPU. This commit also includes the tick_nohz_full_enabled() check suggested by Frederic Weisbecker. Reported-by: Jet Chen <jet.chen@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Created housekeeping_affine() and housekeeping_mask per fweisbec feedback. ]
2014-07-08alarmtimer: Fix bug where relative alarm timers were treated as absoluteJohn Stultz
Sharvil noticed with the posix timer_settime interface, using the CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM clockid, if the users tried to specify a relative time timer, it would incorrectly be treated as absolute regardless of the state of the flags argument. This patch corrects this, properly checking the absolute/relative flag, as well as adds further error checking that no invalid flag bits are set. Reported-by: Sharvil Nanavati <sharvil@google.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Sharvil Nanavati <sharvil@google.com> Cc: stable <stable@vger.kernel.org> #3.0+ Link: http://lkml.kernel.org/r/1404767171-6902-1-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-06-23hrtimer: Remove hrtimer_enqueue_reprogram()Viresh Kumar
We call hrtimer_enqueue_reprogram() only when we are in high resolution mode now so we don't need to check that again in hrtimer_enqueue_reprogram(). Once the check is removed, hrtimer_enqueue_reprogram() turns to be an useless wrapper over hrtimer_reprogram() and can be dropped. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1403393357-2070-6-git-send-email-fweisbec@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-06-23hrtimer: Kick lowres dynticks targets on timer enqueueViresh Kumar
In lowres mode, hrtimers are serviced by the tick instead of a clock event. It works well as long as the tick stays periodic but we must also make sure that the hrtimers are serviced in dynticks mode targets, pretty much like timer list timers do. Note that all dynticks modes are concerned: get_nohz_timer_target() tries not to return remote idle CPUs but there is nothing to prevent the elected target from entering dynticks idle mode until we lock its base. It's also prefectly legal to enqueue hrtimers on full dynticks CPU. So there are two requirements to correctly handle dynticks: 1) On target's tick stop time, we must not delay the next tick further the next hrtimer. 2) On hrtimer queue time. If the tick of the target is stopped, we must wake up that CPU such that it sees the new hrtimer and recalculate the next tick accordingly. The point 1 is well handled currently through get_nohz_timer_interrupt() and cmp_next_hrtimer_event(). But the point 2 isn't handled at all. Fixing this is easy though as we have the necessary API ready for that. All we need is to call wake_up_nohz_cpu() on a target when a newly enqueued hrtimer requires tick rescheduling, like timer list timer do. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/3d7ea08ce008698e26bd39fe10f55949391073ab.1403507178.git.viresh.kumar@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-06-23hrtimer: Store cpu-number in struct hrtimer_cpu_baseViresh Kumar
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>
2014-06-23timer: Kick dynticks targets on mod_timer*() callsViresh Kumar
When a timer is enqueued or modified on a dynticks target, that CPU must re-evaluate the next tick to service that timer. The tick re-evaluation is performed by an IPI kick on the target. Now while we correctly call wake_up_nohz_cpu() from add_timer_on(), the mod_timer*() API family doesn't support so well dynticks targets. The reason for this is likely that __mod_timer() isn't supposed to select an idle target for a timer, unless that target is the current CPU, in which case a dynticks idle kick isn't actually needed. But there is a small race window lurking behind that assumption: the elected target has all the time to turn dynticks idle between the call to get_nohz_timer_target() and the locking of its base. Hence a risk that we enqueue a timer on a dynticks idle destination without kicking it. As a result, the timer might be serviced too late in the future. Also a target elected by __mod_timer() can be in full dynticks mode and thus require to be kicked as well. And unlike idle dynticks, this concern both local and remote targets. To fix this whole issue, lets centralize the dynticks kick to internal_add_timer() so that it is well handled for all sort of timer enqueue. Even timer migration is concerned so that a full dynticks target is correctly kicked as needed when timers are migrating to it. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1403393357-2070-3-git-send-email-fweisbec@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-06-23timer: Store cpu-number in struct tvec_baseViresh Kumar
Timers are serviced by the tick. But when a timer is enqueued on a dynticks target, we need to kick it in order to make it reconsider the next tick to schedule to correctly handle the timer's expiring time. Now while this kick is correctly performed for add_timer_on(), the mod_timer*() family has been a bit neglected. To prepare for fixing this, we need internal_add_timer() to be able to resolve the CPU target associated to a timer's object 'base' so that the kick can be centralized there. This can't be passed as an argument as not all the callers know the CPU number of a timer's base. So lets store it in the struct tvec_base to resolve the CPU without much overhead. It is set once for good at every CPU's first boot. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1403393357-2070-2-git-send-email-fweisbec@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-06-23time/timers: Move all time(r) related files into kernel/timeThomas Gleixner
Except for Kconfig.HZ. That needs a separate treatment. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-06-19alarmtimer: Export symbols of alarmtimer_get_rtcdevPramod Gurav
Export symbol of alarmtimer_get_rtcdev so that it is used by any driver when built as module like, drivers/staging/android/alarm-dev.c. CC: John Stultz <john.stultz@linaro.org> CC: Marcus Gelderie <redmnic@gmail.com> Signed-off-by: Pramod Gurav <pramod.gurav.etc@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-06-16nohz: Support nohz full remote kickFrederic Weisbecker
Remotely kicking a full nohz CPU in order to make it re-evaluate its next tick is currently implemented using the scheduler IPI. However this bloats a scheduler fast path with an off-topic feature. The scheduler tick was abused here for its cool "callable anywhere/anytime" properties. But now that the irq work subsystem can queue remote callbacks, it's a perfect fit to safely queue IPIs when interrupts are disabled without worrying about concurrent callers. So lets implement remote kick on top of irq work. This is going to be used when a new event requires the next tick to be recalculated: more than 1 task competing on the CPU, timer armed, ... Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-06-04Merge branch 'akpm' (patchbomb from Andrew) into nextLinus Torvalds
Merge misc updates from Andrew Morton: - a few fixes for 3.16. Cc'ed to stable so they'll get there somehow. - various misc fixes and cleanups - most of the ocfs2 queue. Review is slow... - most of MM. The MM queue is pretty huge this time, but not much in the way of feature work. - some tweaks under kernel/ - printk maintenance work - updates to lib/ - checkpatch updates - tweaks to init/ * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (276 commits) fs/autofs4/dev-ioctl.c: add __init to autofs_dev_ioctl_init fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul init/main.c: remove an ifdef kthreads: kill CLONE_KERNEL, change kernel_thread(kernel_init) to avoid CLONE_SIGHAND init/main.c: add initcall_blacklist kernel parameter init/main.c: don't use pr_debug() fs/binfmt_flat.c: make old_reloc() static fs/binfmt_elf.c: fix bool assignements fs/efs: convert printk(KERN_DEBUG to pr_debug fs/efs: add pr_fmt / use __func__ fs/efs: convert printk to pr_foo() scripts/checkpatch.pl: device_initcall is not the only __initcall substitute checkpatch: check stable email address checkpatch: warn on unnecessary void function return statements checkpatch: prefer kstrto<foo> to sscanf(buf, "%<lhuidx>", &bar); checkpatch: add warning for kmalloc/kzalloc with multiply checkpatch: warn on #defines ending in semicolon checkpatch: make --strict a default for files in drivers/net and net/ checkpatch: always warn on missing blank line after variable declaration block checkpatch: fix wildcard DT compatible string checking ...