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2017-05-03Merge branch 'for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial Pull trivial tree updates from Jiri Kosina. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: tty: fix comment for __tty_alloc_driver() init/main: properly align the multi-line comment init/main: Fix double "the" in comment Fix dead URLs to ftp.kernel.org drivers: Clean up duplicated email address treewide: Fix typo in xml/driver-api/basics.xml tools/testing/selftests/powerpc: remove redundant CFLAGS in Makefile: "-Wall -O2 -Wall" -> "-O2 -Wall" selftests/timers: Spelling s/privledges/privileges/ HID: picoLCD: Spelling s/REPORT_WRTIE_MEMORY/REPORT_WRITE_MEMORY/ net: phy: dp83848: Fix Typo UBI: Fix typos Documentation: ftrace.txt: Correct nice value of 120 priority net: fec: Fix typo in error msg and comment treewide: Fix typos in printk
2017-05-03Merge branch 'for-linus' of ↵Linus Torvalds1-0/+4
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching Pull livepatch updates from Jiri Kosina: - a per-task consistency model is being added for architectures that support reliable stack dumping (extending this, currently rather trivial set, is currently in the works). This extends the nature of the types of patches that can be applied by live patching infrastructure. The code stems from the design proposal made [1] back in November 2014. It's a hybrid of SUSE's kGraft and RH's kpatch, combining advantages of both: it uses kGraft's per-task consistency and syscall barrier switching combined with kpatch's stack trace switching. There are also a number of fallback options which make it quite flexible. Most of the heavy lifting done by Josh Poimboeuf with help from Miroslav Benes and Petr Mladek [1] https://lkml.kernel.org/r/20141107140458.GA21774@suse.cz - module load time patch optimization from Zhou Chengming - a few assorted small fixes * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching: livepatch: add missing printk newlines livepatch: Cancel transition a safe way for immediate patches livepatch: Reduce the time of finding module symbols livepatch: make klp_mutex proper part of API livepatch: allow removal of a disabled patch livepatch: add /proc/<pid>/patch_state livepatch: change to a per-task consistency model livepatch: store function sizes livepatch: use kstrtobool() in enabled_store() livepatch: move patching functions into patch.c livepatch: remove unnecessary object loaded check livepatch: separate enabled and patched states livepatch/s390: add TIF_PATCH_PENDING thread flag livepatch/s390: reorganize TIF thread flag bits livepatch/powerpc: add TIF_PATCH_PENDING thread flag livepatch/x86: add TIF_PATCH_PENDING thread flag livepatch: create temporary klp_update_patch_state() stub x86/entry: define _TIF_ALLWORK_MASK flags explicitly stacktrace/x86: add function for detecting reliable stack traces
2017-05-02Merge branch 'locking-core-for-linus' of ↵Linus Torvalds1-11/+53
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - a big round of FUTEX_UNLOCK_PI improvements, fixes, cleanups and general restructuring - lockdep updates such as new checks for lock_downgrade() - introduce the new atomic_try_cmpxchg() locking API and use it to optimize refcount code generation - ... plus misc fixes, updates and cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits) MAINTAINERS: Add FUTEX SUBSYSTEM futex: Clarify mark_wake_futex memory barrier usage futex: Fix small (and harmless looking) inconsistencies futex: Avoid freeing an active timer rtmutex: Plug preempt count leak in rt_mutex_futex_unlock() rtmutex: Fix more prio comparisons rtmutex: Fix PI chain order integrity sched,tracing: Update trace_sched_pi_setprio() sched/rtmutex: Refactor rt_mutex_setprio() rtmutex: Clean up sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update sched/rtmutex/deadline: Fix a PI crash for deadline tasks rtmutex: Deboost before waking up the top waiter locking/ww-mutex: Limit stress test to 2 seconds locking/atomic: Fix atomic_try_cmpxchg() semantics lockdep: Fix per-cpu static objects futex: Drop hb->lock before enqueueing on the rtmutex futex: Futex_unlock_pi() determinism futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock() futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock() ...
2017-05-02Merge branch 'sched-core-for-linus' of ↵Linus Torvalds6-291/+494
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The main changes in this cycle were: - another round of rq-clock handling debugging, robustization and fixes - PELT accounting improvements - CPU hotplug related ->cpus_allowed affinity handling fixes all around the tree - ... plus misc fixes, cleanups and updates" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits) sched/x86: Update reschedule warning text crypto: N2 - Replace racy task affinity logic cpufreq/sparc-us2e: Replace racy task affinity logic cpufreq/sparc-us3: Replace racy task affinity logic cpufreq/sh: Replace racy task affinity logic cpufreq/ia64: Replace racy task affinity logic ACPI/processor: Replace racy task affinity logic ACPI/processor: Fix error handling in __acpi_processor_start() sparc/sysfs: Replace racy task affinity logic powerpc/smp: Replace open coded task affinity logic ia64/sn/hwperf: Replace racy task affinity logic ia64/salinfo: Replace racy task affinity logic workqueue: Provide work_on_cpu_safe() ia64/topology: Remove cpus_allowed manipulation sched/fair: Move the PELT constants into a generated header sched/fair: Increase PELT accuracy for small tasks sched/fair: Fix comments sched/Documentation: Add 'sched-pelt' tool sched/fair: Fix corner case in __accumulate_sum() sched/core: Remove 'task' parameter and rename tsk_restore_flags() to current_restore_flags() ...
2017-05-02Merge tag 'pm-4.12-rc1' of ↵Linus Torvalds1-28/+54
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management updates from Rafael Wysocki: "This time the majority of changes go to the cpufreq subsystem (and to the intel_pstate driver in particular) and there are some updates in the generic power domains framework, cpuidle, tools and a couple of other places. One thing worth mentioning is that the intel_pstate's sysfs interface has been reworked to be more consistent with the general expectations of the cpufreq core and less confusing, hopefully for the better. Also, we have a new cpufreq driver for Tegra186 and new hardware support in intel_pstata and the Mediatek cpufreq driver. Apart from that, the AnalyzeSuspend utility for system suspend profiling gets a companion called AnalyzeBoot for the analogous profiling of system boot and they both go into one place under tools/power/pm-graph/. The rest is mostly fixes, cleanups and code reorganization. Specifics: - Rework the intel_pstate driver's sysfs interface to make it more straightforward and more intuitive (Rafael Wysocki). - Make intel_pstate support all processors which advertise HWP (hardware-managed P-states) to the kernel in all operation modes and make it use the load-based P-state selection algorithm on a wider range of systems in the active mode (Rafael Wysocki). - Add cpufreq driver for Tegra186 (Mikko Perttunen). - Add support for Gemini Lake SoCs to intel_pstate (David Box). - Add support for MT8176 and MT817x to the Mediatek cpufreq driver and clean up that driver a bit (Daniel Kurtz). - Clean up intel_pstate and optimize it slightly (Rafael Wysocki). - Update the schedutil cpufreq governor, mostly to fix a couple of issues with it related to specific workloads, and rework its sysfs tunable and initialization a bit (Rafael Wysocki, Viresh Kumar). - Fix minor issues in the imx6q, dbx500 and qoriq cpufreq drivers (Christophe Jaillet, Irina Tirdea, Leonard Crestez, Viresh Kumar, YuanTian Tang). - Add file patterns for cpufreq DT bindings to MAINTAINERS (Geert Uytterhoeven). - Add support for "always on" power domains to the genpd (generic power domains) framework and clean up that code somewhat (Ulf Hansson, Lina Iyer, Viresh Kumar). - Fix minor issues in the powernv cpuidle driver and clean it up (Anton Blanchard, Gautham Shenoy). - Move the AnalyzeSuspend utility under tools/power/pm-graph/ and add an analogous boot-profiling utility called AnalyzeBoot to it (Todd Brandt). - Add rk3328 support to the rockchip-io AVS (Adaptive Voltage Scaling) driver (David Wu). - Fix minor issues in the cpuidle core, the intel_pstate_tracer utility, the devfreq framework and the PM core documentation (Chanwoo Choi, Doug Smythies, Johan Hovold, Marcin Nowakowski)" * tag 'pm-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (56 commits) PM / runtime: Document autosuspend-helper side effects PM / runtime: Fix autosuspend documentation tools: power: pm-graph: Package makefile and man pages tools: power: pm-graph: AnalyzeBoot v2.0 tools: power: pm-graph: AnalyzeSuspend v4.6 cpufreq: Add Tegra186 cpufreq driver cpufreq: imx6q: Fix error handling code cpufreq: imx6q: Set max suspend_freq to avoid changes during suspend cpufreq: imx6q: Fix handling EPROBE_DEFER from regulator cpuidle: powernv: Avoid a branch in the core snooze_loop() loop cpuidle: powernv: Don't continually set thread priority in snooze_loop() cpuidle: powernv: Don't bounce between low and very low thread priority cpuidle: cpuidle-cps: remove unused variable tools/power/x86/intel_pstate_tracer: Adjust directory ownership cpufreq: schedutil: Use policy-dependent transition delays cpufreq: schedutil: Reduce frequencies slower PM / devfreq: Move struct devfreq_governor to devfreq directory PM / Domains: Ignore domain-idle-states that are not compatible cpufreq: intel_pstate: Add support for Gemini Lake powernv-cpuidle: Validate DT property array size ...
2017-05-01Merge branch 'for-4.12' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: "Nothing major. Two notable fixes are Li's second stab at fixing the long-standing race condition in the mount path and suppression of spurious warning from cgroup_get(). All other changes are trivial" * 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: mark cgroup_get() with __maybe_unused cgroup: avoid attaching a cgroup root to two different superblocks, take 2 cgroup: fix spurious warnings on cgroup_is_dead() from cgroup_sk_alloc() cgroup: move cgroup_subsys_state parent field for cache locality cpuset: Remove cpuset_update_active_cpus()'s parameter. cgroup: switch to BUG_ON() cgroup: drop duplicate header nsproxy.h kernel: convert css_set.refcount from atomic_t to refcount_t kernel: convert cgroup_namespace.count from atomic_t to refcount_t
2017-04-29Merge schedutil governor updates for v4.12.Rafael J. Wysocki1-28/+54
2017-04-27sched/cputime: Fix ksoftirqd cputime accounting regressionFrederic Weisbecker2-13/+23
irq_time_read() returns the irqtime minus the ksoftirqd time. This is necessary because irq_time_read() is used to substract the IRQ time from the sum_exec_runtime of a task. If we were to include the softirq time of ksoftirqd, this task would substract its own CPU time everytime it updates ksoftirqd->sum_exec_runtime which would therefore never progress. But this behaviour got broken by: a499a5a14db ("sched/cputime: Increment kcpustat directly on irqtime account") ... which now includes ksoftirqd softirq time in the time returned by irq_time_read(). This has resulted in wrong ksoftirqd cputime reported to userspace through /proc/stat and thus "top" not showing ksoftirqd when it should after intense networking load. ksoftirqd->stime happens to be correct but it gets scaled down by sum_exec_runtime through task_cputime_adjusted(). To fix this, just account the strict IRQ time in a separate counter and use it to report the IRQ time. Reported-and-tested-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Link: http://lkml.kernel.org/r/1493129448-5356-1-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-17cpufreq: schedutil: Use policy-dependent transition delaysRafael J. Wysocki1-5/+10
Make the schedutil governor take the initial (default) value of the rate_limit_us sysfs attribute from the (new) transition_delay_us policy parameter (to be set by the scaling driver). That will allow scaling drivers to make schedutil use smaller default values of rate_limit_us and reduce the default average time interval between consecutive frequency changes. Make intel_pstate set transition_delay_us to 500. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2017-04-14Merge branch 'linus' into locking/core, to pick up fixesIngo Molnar2-32/+34
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-14sched/fair: Move the PELT constants into a generated headerPeter Zijlstra2-18/+16
Now that we have a tool to generate the PELT constants in C form, use its output as a separate header. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-14sched/fair: Increase PELT accuracy for small tasksPeter Zijlstra1-1/+2
We truncate (and loose) the lower 10 bits of runtime in ___update_load_avg(), this means there's a consistent bias to under-account tasks. This is esp. significant for small tasks. Cure this by only forwarding last_update_time to the point we've actually accounted for, leaving the remainder for the next time. Reported-by: Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-14sched/fair: Fix commentsPeter Zijlstra1-10/+10
Historically our periods (or p) argument in PELT denoted the number of full periods (what is now d2). However recent patches have changed this to the total decay (previously p+1), leading to a confusing discrepancy between comments and code. Try and clarify things by making periods (in code) and p (in comments) be the same thing (again). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-14sched/fair: Fix corner case in __accumulate_sum()Peter Zijlstra1-56/+19
Paul noticed that in the (periods >= LOAD_AVG_MAX_N) case in __accumulate_sum(), the returned contribution value (LOAD_AVG_MAX) is incorrect. This is because at this point, the decay_load() on the old state -- the first step in accumulate_sum() -- will not have resulted in 0, and will therefore result in a sum larger than the maximum value of our series. Obviously broken. Note that: decay_load(LOAD_AVG_MAX, LOAD_AVG_MAX_N) = 1 (345 / 32) 47742 * - ^ = ~27 2 Not to mention that any further contribution from the d3 segment (our new period) would also push it over the maximum. Solve this by noting that we can write our c2 term: p c2 = 1024 \Sum y^n n=1 In terms of our maximum value: inf inf p max = 1024 \Sum y^n = 1024 ( \Sum y^n + \Sum y^n + y^0 ) n=0 n=p+1 n=1 Further note that: inf inf inf ( \Sum y^n ) y^p = \Sum y^(n+p) = \Sum y^n n=0 n=0 n=p Combined that gives us: p c2 = 1024 \Sum y^n n=1 inf inf = 1024 ( \Sum y^n - \Sum y^n - y^0 ) n=0 n=p+1 = max - (max y^(p+1)) - 1024 Further simplify things by dealing with p=0 early on. Reported-by: Paul Turner <pjt@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Cc: linux-kernel@vger.kernel.org Fixes: a481db34b9be ("sched/fair: Optimize ___update_sched_avg()") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-13cpufreq: schedutil: Reduce frequencies slowerRafael J. Wysocki1-0/+3
The schedutil governor reduces frequencies too fast in some situations which cases undesirable performance drops to appear. To address that issue, make schedutil reduce the frequency slower by setting it to the average of the value chosen during the previous iteration of governor computations and the new one coming from its frequency selection formula. Link: https://bugzilla.kernel.org/show_bug.cgi?id=194963 Reported-by: John <john.ettedgui@gmail.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2017-04-11Merge tag 'v4.11-rc6' into sched/core, to pick up fixesIngo Molnar2-32/+34
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-11cpuset: Remove cpuset_update_active_cpus()'s parameter.Rakib Mullick1-2/+2
In cpuset_update_active_cpus(), cpu_online isn't used anymore. Remove it. Signed-off-by: Rakib Mullick<rakib.mullick@gmail.com> Acked-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2017-04-04sched,tracing: Update trace_sched_pi_setprio()Peter Zijlstra1-1/+1
Pass the PI donor task, instead of a numerical priority. Numerical priorities are not sufficient to describe state ever since SCHED_DEADLINE. Annotate all sched tracepoints that are currently broken; fixing them will bork userspace. *hate*. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: xlpang@redhat.com Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170323150216.353599881@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-04sched/rtmutex: Refactor rt_mutex_setprio()Peter Zijlstra1-13/+53
With the introduction of SCHED_DEADLINE the whole notion that priority is a single number is gone, therefore the @prio argument to rt_mutex_setprio() doesn't make sense anymore. So rework the code to pass a pi_task instead. Note this also fixes a problem with pi_top_task caching; previously we would not set the pointer (call rt_mutex_update_top_task) if the priority didn't change, this could lead to a stale pointer. As for the XXX, I think its fine to use pi_task->prio, because if it differs from waiter->prio, a PI chain update is immenent. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: xlpang@redhat.com Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170323150216.303827095@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-04sched/rtmutex/deadline: Fix a PI crash for deadline tasksXunlei Pang1-0/+2
A crash happened while I was playing with deadline PI rtmutex. BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 IP: [<ffffffff810eeb8f>] rt_mutex_get_top_task+0x1f/0x30 PGD 232a75067 PUD 230947067 PMD 0 Oops: 0000 [#1] SMP CPU: 1 PID: 10994 Comm: a.out Not tainted Call Trace: [<ffffffff810b658c>] enqueue_task+0x2c/0x80 [<ffffffff810ba763>] activate_task+0x23/0x30 [<ffffffff810d0ab5>] pull_dl_task+0x1d5/0x260 [<ffffffff810d0be6>] pre_schedule_dl+0x16/0x20 [<ffffffff8164e783>] __schedule+0xd3/0x900 [<ffffffff8164efd9>] schedule+0x29/0x70 [<ffffffff8165035b>] __rt_mutex_slowlock+0x4b/0xc0 [<ffffffff81650501>] rt_mutex_slowlock+0xd1/0x190 [<ffffffff810eeb33>] rt_mutex_timed_lock+0x53/0x60 [<ffffffff810ecbfc>] futex_lock_pi.isra.18+0x28c/0x390 [<ffffffff810ed8b0>] do_futex+0x190/0x5b0 [<ffffffff810edd50>] SyS_futex+0x80/0x180 This is because rt_mutex_enqueue_pi() and rt_mutex_dequeue_pi() are only protected by pi_lock when operating pi waiters, while rt_mutex_get_top_task(), will access them with rq lock held but not holding pi_lock. In order to tackle it, we introduce new "pi_top_task" pointer cached in task_struct, and add new rt_mutex_update_top_task() to update its value, it can be called by rt_mutex_setprio() which held both owner's pi_lock and rq lock. Thus "pi_top_task" can be safely accessed by enqueue_task_dl() under rq lock. Originally-From: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Xunlei Pang <xlpang@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170323150216.157682758@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-02Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds1-19/+27
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Thomas Gleixner: "This update provides: - make the scheduler clock switch to unstable mode smooth so the timestamps stay at microseconds granularity instead of switching to tick granularity. - unbreak perf test tsc by taking the new offset into account which was added in order to proveide better sched clock continuity - switching sched clock to unstable mode runs all clock related computations which affect the sched clock output itself from a work queue. In case of preemption sched clock uses half updated data and provides wrong timestamps. Keep the math in the protected context and delegate only the static key switch to workqueue context. - remove a duplicate header include" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/headers: Remove duplicate #include <linux/sched/debug.h> line sched/clock: Fix broken stable to unstable transfer sched/clock, x86/perf: Fix "perf test tsc" sched/clock: Fix clear_sched_clock_stable() preempt wobbly
2017-03-30sched/fair: Optimize ___update_sched_avg()Yuyang Du1-94/+118
The main PELT function ___update_load_avg(), which implements the accumulation and progression of the geometric average series, is implemented along the following lines for the scenario where the time delta spans all 3 possible sections (see figure below): 1. add the remainder of the last incomplete period 2. decay old sum 3. accumulate new sum in full periods since last_update_time 4. accumulate the current incomplete period 5. update averages Or: d1 d2 d3 ^ ^ ^ | | | |<->|<----------------->|<--->| ... |---x---|------| ... |------|-----x (now) load_sum' = (load_sum + weight * scale * d1) * y^(p+1) + (1,2) p weight * scale * 1024 * \Sum y^n + (3) n=1 weight * scale * d3 * y^0 (4) load_avg' = load_sum' / LOAD_AVG_MAX (5) Where: d1 - is the delta part completing the remainder of the last incomplete period, d2 - is the delta part spannind complete periods, and d3 - is the delta part starting the current incomplete period. We can simplify the code in two steps; the first step is to separate the first term into new and old parts like: (load_sum + weight * scale * d1) * y^(p+1) = load_sum * y^(p+1) + weight * scale * d1 * y^(p+1) Once we've done that, its easy to see that all new terms carry the common factors: weight * scale If we factor those out, we arrive at the form: load_sum' = load_sum * y^(p+1) + weight * scale * (d1 * y^(p+1) + p 1024 * \Sum y^n + n=1 d3 * y^0) Which results in a simpler, smaller and faster implementation. Signed-off-by: Yuyang Du <yuyang.du@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bsegall@google.com Cc: dietmar.eggemann@arm.com Cc: matt@codeblueprint.co.uk Cc: morten.rasmussen@arm.com Cc: pjt@google.com Cc: umgwanakikbuti@gmail.com Cc: vincent.guittot@linaro.org Link: http://lkml.kernel.org/r/1486935863-25251-3-git-send-email-yuyang.du@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-30sched/fair: Explicitly generate __update_load_avg() instancesPeter Zijlstra1-18/+38
The __update_load_avg() function is an __always_inline because its used with constant propagation to generate different variants of the code without having to duplicate it (which would be prone to bugs). Explicitly instantiate the 3 variants. Note that most of this is called from rather hot paths, so reducing branches is good. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-27sched/clock: Fix broken stable to unstable transferPavel Tatashin1-4/+5
When it is determined that the clock is actually unstable, and we switch from stable to unstable, the __clear_sched_clock_stable() function is eventually called. In this function we set gtod_offset so the following holds true: sched_clock() + raw_offset == ktime_get_ns() + gtod_offset But instead of getting the latest timestamps, we use the last values from scd, so instead of sched_clock() we use scd->tick_raw, and instead of ktime_get_ns() we use scd->tick_gtod. However, later, when we use gtod_offset sched_clock_local() we do not add it to scd->tick_gtod to calculate the correct clock value when we determine the boundaries for min/max clocks. This can result in tick granularity sched_clock() values, so fix it. Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hpa@zytor.com Fixes: 5680d8094ffa ("sched/clock: Provide better clock continuity") Link: http://lkml.kernel.org/r/1490214265-899964-2-git-send-email-pasha.tatashin@oracle.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-27sched/fair: Prefer sibiling only if local group is under-utilizedSrikar Dronamraju1-3/+4
If the child domain prefers tasks to go siblings, the local group could end up pulling tasks to itself even if the local group is almost equally loaded as the source group. Lets assume a 4 core,smt==2 machine running 5 thread ebizzy workload. Everytime, local group has capacity and source group has atleast 2 threads, local group tries to pull the task. This causes the threads to constantly move between different cores. This is even more profound if the cores have more threads, like in Power 8, smt 8 mode. Fix this by only allowing local group to pull a task, if the source group has more number of tasks than the local group. Here are the relevant perf stat numbers of a 22 core,smt 8 Power 8 machine. Without patch: Performance counter stats for 'ebizzy -t 22 -S 100' (5 runs): 1,440 context-switches # 0.001 K/sec ( +- 1.26% ) 366 cpu-migrations # 0.000 K/sec ( +- 5.58% ) 3,933 page-faults # 0.002 K/sec ( +- 11.08% ) Performance counter stats for 'ebizzy -t 48 -S 100' (5 runs): 6,287 context-switches # 0.001 K/sec ( +- 3.65% ) 3,776 cpu-migrations # 0.001 K/sec ( +- 4.84% ) 5,702 page-faults # 0.001 K/sec ( +- 9.36% ) Performance counter stats for 'ebizzy -t 96 -S 100' (5 runs): 8,776 context-switches # 0.001 K/sec ( +- 0.73% ) 2,790 cpu-migrations # 0.000 K/sec ( +- 0.98% ) 10,540 page-faults # 0.001 K/sec ( +- 3.12% ) With patch: Performance counter stats for 'ebizzy -t 22 -S 100' (5 runs): 1,133 context-switches # 0.001 K/sec ( +- 4.72% ) 123 cpu-migrations # 0.000 K/sec ( +- 3.42% ) 3,858 page-faults # 0.002 K/sec ( +- 8.52% ) Performance counter stats for 'ebizzy -t 48 -S 100' (5 runs): 2,169 context-switches # 0.000 K/sec ( +- 6.19% ) 189 cpu-migrations # 0.000 K/sec ( +- 12.75% ) 5,917 page-faults # 0.001 K/sec ( +- 8.09% ) Performance counter stats for 'ebizzy -t 96 -S 100' (5 runs): 5,333 context-switches # 0.001 K/sec ( +- 5.91% ) 506 cpu-migrations # 0.000 K/sec ( +- 3.35% ) 10,792 page-faults # 0.001 K/sec ( +- 7.75% ) Which show that in these workloads CPU migrations get reduced significantly. Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: http://lkml.kernel.org/r/1490205470-10249-1-git-send-email-srikar@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-25Merge back schedutil governor updates for 4.12.Rafael J. Wysocki1-23/+41
2017-03-24treewide: Fix typo in xml/driver-api/basics.xmlMasanari Iida1-1/+1
This patch fix spelling typos found in Documentation/output/xml/driver-api/basics.xml. It is because the xml file was generated from comments in source, so I had to fix the comments. Signed-off-by: Masanari Iida <standby24x7@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2017-03-24cpufreq: schedutil: Trace frequency only if it has changedRafael J. Wysocki1-9/+7
sugov_update_commit() calls trace_cpu_frequency() to record the current CPU frequency if it has not changed in the fast switch case to prevent utilities from getting confused (they may report that the CPU is idle if the frequency has not been recorded for too long, for example). However, that may cause the tracepoint to be triggered quite often for no real reason (if the frequency doesn't change, we will not modify the last update time stamp and governor computations may run again shortly when that happens), so don't do that (arguably, it is done to work around a utilities bug anyway). That allows code duplication in sugov_update_commit() to be reduced somewhat too. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2017-03-23sched/fair: Fix FTQ noise bench regressionVincent Guittot1-3/+36
A regression of the FTQ noise has been reported by Ying Huang, on the following hardware: 8 threads Intel(R) Core(TM)i7-4770 CPU @ 3.40GHz with 8G memory ... which was caused by this commit: commit 4e5160766fcc ("sched/fair: Propagate asynchrous detach") The only part of the patch that can increase the noise is the update of blocked load of group entity in update_blocked_averages(). We can optimize this call and skip the update of group entity if its load and utilization are already null and there is no pending propagation of load in the task group. This optimization partly restores the noise score. A more agressive optimization has been tried but has shown worse score. Reported-by: ying.huang@linux.intel.com Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dietmar.eggemann@arm.com Cc: ying.huang@intel.com Fixes: 4e5160766fcc ("sched/fair: Propagate asynchrous detach") Link: http://lkml.kernel.org/r/1489758442-2877-1-git-send-email-vincent.guittot@linaro.org [ Fixed typos, improved layout. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-23sched/core: Fix rq lock pinning warning after call balance callbacksWanpeng Li1-3/+3
This can be reproduced by running rt-migrate-test: WARNING: CPU: 2 PID: 2195 at kernel/locking/lockdep.c:3670 lock_unpin_lock() unpinning an unpinned lock ... Call Trace: dump_stack() __warn() warn_slowpath_fmt() lock_unpin_lock() __balance_callback() __schedule() schedule() futex_wait_queue_me() futex_wait() do_futex() SyS_futex() do_syscall_64() entry_SYSCALL64_slow_path() Revert the rq_lock_irqsave() usage here, the whole point of the balance_callback() was to allow dropping rq->lock. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 8a8c69c32778 ("sched/core: Add rq->lock wrappers") Link: http://lkml.kernel.org/r/1489718719-3951-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-23sched/clock, x86/perf: Fix "perf test tsc"Peter Zijlstra1-11/+11
People reported that commit: 5680d8094ffa ("sched/clock: Provide better clock continuity") broke "perf test tsc". That commit added another offset to the reported clock value; so take that into account when computing the provided offset values. Reported-by: Adrian Hunter <adrian.hunter@intel.com> Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org> Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 5680d8094ffa ("sched/clock: Provide better clock continuity") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-23sched/clock: Fix clear_sched_clock_stable() preempt wobblyPeter Zijlstra1-5/+12
Paul reported a problems with clear_sched_clock_stable(). Since we run all of __clear_sched_clock_stable() from workqueue context, there's a preempt problem. Solve it by only running the static_key_disable() from workqueue. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: fweisbec@gmail.com Link: http://lkml.kernel.org/r/20170313124621.GA3328@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-23cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurelyRafael J. Wysocki1-0/+27
The way the schedutil governor uses the PELT metric causes it to underestimate the CPU utilization in some cases. That can be easily demonstrated by running kernel compilation on a Sandy Bridge Intel processor, running turbostat in parallel with it and looking at the values written to the MSR_IA32_PERF_CTL register. Namely, the expected result would be that when all CPUs were 100% busy, all of them would be requested to run in the maximum P-state, but observation shows that this clearly isn't the case. The CPUs run in the maximum P-state for a while and then are requested to run slower and go back to the maximum P-state after a while again. That causes the actual frequency of the processor to visibly oscillate below the sustainable maximum in a jittery fashion which clearly is not desirable. That has been attributed to CPU utilization metric updates on task migration that cause the total utilization value for the CPU to be reduced by the utilization of the migrated task. If that happens, the schedutil governor may see a CPU utilization reduction and will attempt to reduce the CPU frequency accordingly right away. That may be premature, though, for example if the system is generally busy and there are other runnable tasks waiting to be run on that CPU already. This is unlikely to be an issue on systems where cpufreq policies are shared between multiple CPUs, because in those cases the policy utilization is computed as the maximum of the CPU utilization values over the whole policy and if that turns out to be low, reducing the frequency for the policy most likely is a good idea anyway. On systems with one CPU per policy, however, it may affect performance adversely and even lead to increased energy consumption in some cases. On those systems it may be addressed by taking another utilization metric into consideration, like whether or not the CPU whose frequency is about to be reduced has been idle recently, because if that's not the case, the CPU is likely to be busy in the near future and its frequency should not be reduced. To that end, use the counter of idle calls in the timekeeping code. Namely, make the schedutil governor look at that counter for the current CPU every time before its frequency is about to be reduced. If the counter has not changed since the previous iteration of the governor computations for that CPU, the CPU has been busy for all that time and its frequency should not be decreased, so if the new frequency would be lower than the one set previously, the governor will skip the frequency update. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Joel Fernandes <joelaf@google.com>
2017-03-21cpufreq: schedutil: Fix per-CPU structure initialization in sugov_start()Rafael J. Wysocki1-13/+7
sugov_start() only initializes struct sugov_cpu per-CPU structures for shared policies, but it should do that for single-CPU policies too. That in particular makes the IO-wait boost mechanism work in the cases when cpufreq policies correspond to individual CPUs. Fixes: 21ca6d2c52f8 (cpufreq: schedutil: Add iowait boosting) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
2017-03-16sched/core: Avoid double update_rq_clock() in move_queued_task()Peter Zijlstra1-1/+2
Address this case: WARNING: CPU: 0 PID: 2070 at ../kernel/sched/core.c:109 update_rq_clock+0x74/0x80 rq->clock_update_flags & RQCF_UPDATED Call Trace: update_rq_clock() move_queued_task() __set_cpus_allowed_ptr() ... Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Fix double update_rq_clock) calls in attach_task()/detach_task()Peter Zijlstra1-2/+4
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Avoid obvious double update_rq_clock()Peter Zijlstra1-8/+10
Add DEQUEUE_NOCLOCK to all places where we just did an update_rq_clock() already. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Simplify update_rq_clock() in __schedule()Peter Zijlstra1-5/+3
Instead of relying on deactivate_task() to call update_rq_clock() and handling the case where it didn't happen (task_on_rq_queued), unconditionally do update_rq_clock() and skip any further updates. This also avoids a double update on deactivate_task() + ttwu_local(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Make sched_ttwu_pending() atomic in timePeter Zijlstra1-1/+3
Since all tasks on the wake_list are woken under a single rq->lock avoid calling update_rq_clock() for each task. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Add ENQUEUE_NOCLOCK to ENQUEUE_RESTOREPeter Zijlstra1-4/+4
In all cases, ENQUEUE_RESTORE should also have ENQUEUE_NOCLOCK because DEQUEUE_SAVE will have done an update_rq_clock(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Add {EN,DE}QUEUE_NOCLOCK flagsPeter Zijlstra2-5/+13
Currently {en,de}queue_task() do an unconditional update_rq_clock(). However since we want to avoid duplicate updates, so that each rq->lock section appears atomic in time, we need to be able to skip these clock updates. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Add rq->lock wrappersPeter Zijlstra3-112/+171
The missing update_rq_clock() check can work with partial rq->lock wrappery, since a missing wrapper can cause the warning to not be emitted when it should have, but cannot cause the warning to trigger when it should not have. The duplicate update_rq_clock() check however can cause false warnings to trigger. Therefore add more comprehensive rq->lock wrappery. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/core: Add WARNING for multiple update_rq_clock() callsPeter Zijlstra2-0/+10
Now that we have no missing calls, add a warning to find multiple calls. By having only a single update_rq_clock() call per rq-lock section, the section appears 'atomic' wrt time. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/rt: Add comments describing the RT IPI pull methodSteven Rostedt (VMware)1-0/+81
While looking into optimizations for the RT scheduler IPI logic, I realized that the comments are lacking to describe it efficiently. It deserves a lengthy description describing its design. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Clark Williams <williams@redhat.com> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170228155030.30c69068@gandalf.local.home [ Small typographical edits. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/deadline: Use deadline instead of period when calculating overflowSteven Rostedt (VMware)1-4/+4
I was testing Daniel's changes with his test case, and tweaked it a little. Instead of having the runtime equal to the deadline, I increased the deadline ten fold. Daniel's test case had: attr.sched_runtime = 2 * 1000 * 1000; /* 2 ms */ attr.sched_deadline = 2 * 1000 * 1000; /* 2 ms */ attr.sched_period = 2 * 1000 * 1000 * 1000; /* 2 s */ To make it more interesting, I changed it to: attr.sched_runtime = 2 * 1000 * 1000; /* 2 ms */ attr.sched_deadline = 20 * 1000 * 1000; /* 20 ms */ attr.sched_period = 2 * 1000 * 1000 * 1000; /* 2 s */ The results were rather surprising. The behavior that Daniel's patch was fixing came back. The task started using much more than .1% of the CPU. More like 20%. Looking into this I found that it was due to the dl_entity_overflow() constantly returning true. That's because it uses the relative period against relative runtime vs the absolute deadline against absolute runtime. runtime / (deadline - t) > dl_runtime / dl_period There's even a comment mentioning this, and saying that when relative deadline equals relative period, that the equation is the same as using deadline instead of period. That comment is backwards! What we really want is: runtime / (deadline - t) > dl_runtime / dl_deadline We care about if the runtime can make its deadline, not its period. And then we can say "when the deadline equals the period, the equation is the same as using dl_period instead of dl_deadline". After correcting this, now when the task gets enqueued, it can throttle correctly, and Daniel's fix to the throttling of sleeping deadline tasks works even when the runtime and deadline are not the same. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it> Link: http://lkml.kernel.org/r/02135a27f1ae3fe5fd032568a5a2f370e190e8d7.1488392936.git.bristot@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/deadline: Throttle a constrained deadline task activated after the ↵Daniel Bristot de Oliveira1-0/+45
deadline During the activation, CBS checks if it can reuse the current task's runtime and period. If the deadline of the task is in the past, CBS cannot use the runtime, and so it replenishes the task. This rule works fine for implicit deadline tasks (deadline == period), and the CBS was designed for implicit deadline tasks. However, a task with constrained deadline (deadine < period) might be awakened after the deadline, but before the next period. In this case, replenishing the task would allow it to run for runtime / deadline. As in this case deadline < period, CBS enables a task to run for more than the runtime / period. In a very loaded system, this can cause a domino effect, making other tasks miss their deadlines. To avoid this problem, in the activation of a constrained deadline task after the deadline but before the next period, throttle the task and set the replenishing timer to the begin of the next period, unless it is boosted. Reproducer: --------------- %< --------------- int main (int argc, char **argv) { int ret; int flags = 0; unsigned long l = 0; struct timespec ts; struct sched_attr attr; memset(&attr, 0, sizeof(attr)); attr.size = sizeof(attr); attr.sched_policy = SCHED_DEADLINE; attr.sched_runtime = 2 * 1000 * 1000; /* 2 ms */ attr.sched_deadline = 2 * 1000 * 1000; /* 2 ms */ attr.sched_period = 2 * 1000 * 1000 * 1000; /* 2 s */ ts.tv_sec = 0; ts.tv_nsec = 2000 * 1000; /* 2 ms */ ret = sched_setattr(0, &attr, flags); if (ret < 0) { perror("sched_setattr"); exit(-1); } for(;;) { /* XXX: you may need to adjust the loop */ for (l = 0; l < 150000; l++); /* * The ideia is to go to sleep right before the deadline * and then wake up before the next period to receive * a new replenishment. */ nanosleep(&ts, NULL); } exit(0); } --------------- >% --------------- On my box, this reproducer uses almost 50% of the CPU time, which is obviously wrong for a task with 2/2000 reservation. Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it> Link: http://lkml.kernel.org/r/edf58354e01db46bf42df8d2dd32418833f68c89.1488392936.git.bristot@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/deadline: Make sure the replenishment timer fires in the next periodDaniel Bristot de Oliveira1-2/+7
Currently, the replenishment timer is set to fire at the deadline of a task. Although that works for implicit deadline tasks because the deadline is equals to the begin of the next period, that is not correct for constrained deadline tasks (deadline < period). For instance: f.c: --------------- %< --------------- int main (void) { for(;;); } --------------- >% --------------- # gcc -o f f.c # trace-cmd record -e sched:sched_switch \ -e syscalls:sys_exit_sched_setattr \ chrt -d --sched-runtime 490000000 \ --sched-deadline 500000000 \ --sched-period 1000000000 0 ./f # trace-cmd report | grep "{pid of ./f}" After setting parameters, the task is replenished and continue running until being throttled: f-11295 [003] 13322.113776: sys_exit_sched_setattr: 0x0 The task is throttled after running 492318 ms, as expected: f-11295 [003] 13322.606094: sched_switch: f:11295 [-1] R ==> watchdog/3:32 [0] But then, the task is replenished 500719 ms after the first replenishment: <idle>-0 [003] 13322.614495: sched_switch: swapper/3:0 [120] R ==> f:11295 [-1] Running for 490277 ms: f-11295 [003] 13323.104772: sched_switch: f:11295 [-1] R ==> swapper/3:0 [120] Hence, in the first period, the task runs 2 * runtime, and that is a bug. During the first replenishment, the next deadline is set one period away. So the runtime / period starts to be respected. However, as the second replenishment took place in the wrong instant, the next replenishment will also be held in a wrong instant of time. Rather than occurring in the nth period away from the first activation, it is taking place in the (nth period - relative deadline). Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Luca Abeni <luca.abeni@santannapisa.it> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it> Link: http://lkml.kernel.org/r/ac50d89887c25285b47465638354b63362f8adff.1488392936.git.bristot@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/loadavg: Use {READ,WRITE}_ONCE() for sample windowMatt Fleming1-7/+11
'calc_load_update' is accessed without any kind of locking and there's a clear assumption in the code that only a single value is read or written. Make this explicit by using READ_ONCE() and WRITE_ONCE(), and avoid unintentionally seeing multiple values, or having the load/stores split. Technically the loads in calc_global_*() don't require this since those are the only functions that update 'calc_load_update', but I've added the READ_ONCE() for consistency. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: http://lkml.kernel.org/r/20170217120731.11868-3-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/loadavg: Avoid loadavg spikes caused by delayed NO_HZ accountingMatt Fleming1-2/+2
If we crossed a sample window while in NO_HZ we will add LOAD_FREQ to the pending sample window time on exit, setting the next update not one window into the future, but two. This situation on exiting NO_HZ is described by: this_rq->calc_load_update < jiffies < calc_load_update In this scenario, what we should be doing is: this_rq->calc_load_update = calc_load_update [ next window ] But what we actually do is: this_rq->calc_load_update = calc_load_update + LOAD_FREQ [ next+1 window ] This has the effect of delaying load average updates for potentially up to ~9seconds. This can result in huge spikes in the load average values due to per-cpu uninterruptible task counts being out of sync when accumulated across all CPUs. It's safe to update the per-cpu active count if we wake between sample windows because any load that we left in 'calc_load_idle' will have been zero'd when the idle load was folded in calc_global_load(). This issue is easy to reproduce before, commit 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") just by forking short-lived process pipelines built from ps(1) and grep(1) in a loop. I'm unable to reproduce the spikes after that commit, but the bug still seems to be present from code review. Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Fixes: commit 5167e8d ("sched/nohz: Rewrite and fix load-avg computation -- again") Link: http://lkml.kernel.org/r/20170217120731.11868-2-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16sched/deadline: Add missing update_rq_clock() in dl_task_timer()Wanpeng Li1-0/+1
The following warning can be triggered by hot-unplugging the CPU on which an active SCHED_DEADLINE task is running on: ------------[ cut here ]------------ WARNING: CPU: 7 PID: 0 at kernel/sched/sched.h:833 replenish_dl_entity+0x71e/0xc40 rq->clock_update_flags < RQCF_ACT_SKIP CPU: 7 PID: 0 Comm: swapper/7 Tainted: G B 4.11.0-rc1+ #24 Hardware name: LENOVO ThinkCentre M8500t-N000/SHARKBAY, BIOS FBKTC1AUS 02/16/2016 Call Trace: <IRQ> dump_stack+0x85/0xc4 __warn+0x172/0x1b0 warn_slowpath_fmt+0xb4/0xf0 ? __warn+0x1b0/0x1b0 ? debug_check_no_locks_freed+0x2c0/0x2c0 ? cpudl_set+0x3d/0x2b0 replenish_dl_entity+0x71e/0xc40 enqueue_task_dl+0x2ea/0x12e0 ? dl_task_timer+0x777/0x990 ? __hrtimer_run_queues+0x270/0xa50 dl_task_timer+0x316/0x990 ? enqueue_task_dl+0x12e0/0x12e0 ? enqueue_task_dl+0x12e0/0x12e0 __hrtimer_run_queues+0x270/0xa50 ? hrtimer_cancel+0x20/0x20 ? hrtimer_interrupt+0x119/0x600 hrtimer_interrupt+0x19c/0x600 ? trace_hardirqs_off+0xd/0x10 local_apic_timer_interrupt+0x74/0xe0 smp_apic_timer_interrupt+0x76/0xa0 apic_timer_interrupt+0x93/0xa0 The DL task will be migrated to a suitable later deadline rq once the DL timer fires and currnet rq is offline. The rq clock of the new rq should be updated. This patch fixes it by updating the rq clock after holding the new rq's rq lock. Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1488865888-15894-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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