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2019-12-21Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds2-3/+15
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Misc fixes: a (rare) PSI crash fix, a CPU affinity related balancing fix, and a toning down of active migration attempts" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/cfs: fix spurious active migration sched/fair: Fix find_idlest_group() to handle CPU affinity psi: Fix a division error in psi poll() sched/psi: Fix sampling error and rare div0 crashes with cgroups and high uptime
2019-12-17sched/cfs: fix spurious active migrationVincent Guittot1-1/+8
The load balance can fail to find a suitable task during the periodic check because the imbalance is smaller than half of the load of the waiting tasks. This results in the increase of the number of failed load balance, which can end up to start an active migration. This active migration is useless because the current running task is not a better choice than the waiting ones. In fact, the current task was probably not running but waiting for the CPU during one of the previous attempts and it had already not been selected. When load balance fails too many times to migrate a task, we should relax the contraint on the maximum load of the tasks that can be migrated similarly to what is done with cache hotness. Before the rework, load balance used to set the imbalance to the average load_per_task in order to mitigate such situation. This increased the likelihood of migrating a task but also of selecting a larger task than needed while more appropriate ones were in the list. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1575036287-6052-1-git-send-email-vincent.guittot@linaro.org
2019-12-17sched/fair: Fix find_idlest_group() to handle CPU affinityVincent Guittot1-0/+4
Because of CPU affinity, the local group can be skipped which breaks the assumption that statistics are always collected for local group. With uninitialized local_sgs, the comparison is meaningless and the behavior unpredictable. This can even end up to use local pointer which is to NULL in this case. If the local group has been skipped because of CPU affinity, we return the idlest group. Fixes: 57abff067a08 ("sched/fair: Rework find_idlest_group()") Reported-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Tested-by: John Stultz <john.stultz@linaro.org> Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: mingo@redhat.com Cc: mgorman@suse.de Cc: juri.lelli@redhat.com Cc: dietmar.eggemann@arm.com Cc: bsegall@google.com Cc: qais.yousef@arm.com Link: https://lkml.kernel.org/r/1575483700-22153-1-git-send-email-vincent.guittot@linaro.org
2019-12-17psi: Fix a division error in psi poll()Johannes Weiner1-1/+1
The psi window size is a u64 an can be up to 10 seconds right now, which exceeds the lower 32 bits of the variable. We currently use div_u64 for it, which is meant only for 32-bit divisors. The result is garbage pressure sampling values and even potential div0 crashes. Use div64_u64. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Cc: Jingfeng Xie <xiejingfeng@linux.alibaba.com> Link: https://lkml.kernel.org/r/20191203183524.41378-3-hannes@cmpxchg.org
2019-12-17sched/psi: Fix sampling error and rare div0 crashes with cgroups and high uptimeJohannes Weiner1-1/+2
Jingfeng reports rare div0 crashes in psi on systems with some uptime: [58914.066423] divide error: 0000 [#1] SMP [58914.070416] Modules linked in: ipmi_poweroff ipmi_watchdog toa overlay fuse tcp_diag inet_diag binfmt_misc aisqos(O) aisqos_hotfixes(O) [58914.083158] CPU: 94 PID: 140364 Comm: kworker/94:2 Tainted: G W OE K 4.9.151-015.ali3000.alios7.x86_64 #1 [58914.093722] Hardware name: Alibaba Alibaba Cloud ECS/Alibaba Cloud ECS, BIOS 3.23.34 02/14/2019 [58914.102728] Workqueue: events psi_update_work [58914.107258] task: ffff8879da83c280 task.stack: ffffc90059dcc000 [58914.113336] RIP: 0010:[] [] psi_update_stats+0x1c1/0x330 [58914.122183] RSP: 0018:ffffc90059dcfd60 EFLAGS: 00010246 [58914.127650] RAX: 0000000000000000 RBX: ffff8858fe98be50 RCX: 000000007744d640 [58914.134947] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00003594f700648e [58914.142243] RBP: ffffc90059dcfdf8 R08: 0000359500000000 R09: 0000000000000000 [58914.149538] R10: 0000000000000000 R11: 0000000000000000 R12: 0000359500000000 [58914.156837] R13: 0000000000000000 R14: 0000000000000000 R15: ffff8858fe98bd78 [58914.164136] FS: 0000000000000000(0000) GS:ffff887f7f380000(0000) knlGS:0000000000000000 [58914.172529] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [58914.178467] CR2: 00007f2240452090 CR3: 0000005d5d258000 CR4: 00000000007606f0 [58914.185765] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [58914.193061] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [58914.200360] PKRU: 55555554 [58914.203221] Stack: [58914.205383] ffff8858fe98bd48 00000000000002f0 0000002e81036d09 ffffc90059dcfde8 [58914.213168] ffff8858fe98bec8 0000000000000000 0000000000000000 0000000000000000 [58914.220951] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [58914.228734] Call Trace: [58914.231337] [] psi_update_work+0x22/0x60 [58914.237067] [] process_one_work+0x189/0x420 [58914.243063] [] worker_thread+0x4e/0x4b0 [58914.248701] [] ? process_one_work+0x420/0x420 [58914.254869] [] kthread+0xe6/0x100 [58914.259994] [] ? kthread_park+0x60/0x60 [58914.265640] [] ret_from_fork+0x39/0x50 [58914.271193] Code: 41 29 c3 4d 39 dc 4d 0f 42 dc <49> f7 f1 48 8b 13 48 89 c7 48 c1 [58914.279691] RIP [] psi_update_stats+0x1c1/0x330 The crashing instruction is trying to divide the observed stall time by the sampling period. The period, stored in R8, is not 0, but we are dividing by the lower 32 bits only, which are all 0 in this instance. We could switch to a 64-bit division, but the period shouldn't be that big in the first place. It's the time between the last update and the next scheduled one, and so should always be around 2s and comfortably fit into 32 bits. The bug is in the initialization of new cgroups: we schedule the first sampling event in a cgroup as an offset of sched_clock(), but fail to initialize the last_update timestamp, and it defaults to 0. That results in a bogusly large sampling period the first time we run the sampling code, and consequently we underreport pressure for the first 2s of a cgroup's life. But worse, if sched_clock() is sufficiently advanced on the system, and the user gets unlucky, the period's lower 32 bits can all be 0 and the sampling division will crash. Fix this by initializing the last update timestamp to the creation time of the cgroup, thus correctly marking the start of the first pressure sampling period in a new cgroup. Reported-by: Jingfeng Xie <xiejingfeng@linux.alibaba.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Suren Baghdasaryan <surenb@google.com> Link: https://lkml.kernel.org/r/20191203183524.41378-2-hannes@cmpxchg.org
2019-12-12cpufreq: Avoid leaving stale IRQ work items during CPU offlineRafael J. Wysocki2-5/+21
The scheduler code calling cpufreq_update_util() may run during CPU offline on the target CPU after the IRQ work lists have been flushed for it, so the target CPU should be prevented from running code that may queue up an IRQ work item on it at that point. Unfortunately, that may not be the case if dvfs_possible_from_any_cpu is set for at least one cpufreq policy in the system, because that allows the CPU going offline to run the utilization update callback of the cpufreq governor on behalf of another (online) CPU in some cases. If that happens, the cpufreq governor callback may queue up an IRQ work on the CPU running it, which is going offline, and the IRQ work may not be flushed after that point. Moreover, that IRQ work cannot be flushed until the "offlining" CPU goes back online, so if any other CPU calls irq_work_sync() to wait for the completion of that IRQ work, it will have to wait until the "offlining" CPU is back online and that may not happen forever. In particular, a system-wide deadlock may occur during CPU online as a result of that. The failing scenario is as follows. CPU0 is the boot CPU, so it creates a cpufreq policy and becomes the "leader" of it (policy->cpu). It cannot go offline, because it is the boot CPU. Next, other CPUs join the cpufreq policy as they go online and they leave it when they go offline. The last CPU to go offline, say CPU3, may queue up an IRQ work while running the governor callback on behalf of CPU0 after leaving the cpufreq policy because of the dvfs_possible_from_any_cpu effect described above. Then, CPU0 is the only online CPU in the system and the stale IRQ work is still queued on CPU3. When, say, CPU1 goes back online, it will run irq_work_sync() to wait for that IRQ work to complete and so it will wait for CPU3 to go back online (which may never happen even in principle), but (worse yet) CPU0 is waiting for CPU1 at that point too and a system-wide deadlock occurs. To address this problem notice that CPUs which cannot run cpufreq utilization update code for themselves (for example, because they have left the cpufreq policies that they belonged to), should also be prevented from running that code on behalf of the other CPUs that belong to a cpufreq policy with dvfs_possible_from_any_cpu set and so in that case the cpufreq_update_util_data pointer of the CPU running the code must not be NULL as well as for the CPU which is the target of the cpufreq utilization update in progress. Accordingly, change cpufreq_this_cpu_can_update() into a regular function in kernel/sched/cpufreq.c (instead of a static inline in a header file) and make it check the cpufreq_update_util_data pointer of the local CPU if dvfs_possible_from_any_cpu is set for the target cpufreq policy. Also update the schedutil governor to do the cpufreq_this_cpu_can_update() check in the non-fast-switch case too to avoid the stale IRQ work issues. Fixes: 99d14d0e16fa ("cpufreq: Process remote callbacks from any CPU if the platform permits") Link: https://lore.kernel.org/linux-pm/20191121093557.bycvdo4xyinbc5cb@vireshk-i7/ Reported-by: Anson Huang <anson.huang@nxp.com> Tested-by: Anson Huang <anson.huang@nxp.com> Cc: 4.14+ <stable@vger.kernel.org> # 4.14+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Peng Fan <peng.fan@nxp.com> (i.MX8QXP-MEK) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-12-05Merge branch 'thermal/next' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux Pull thermal management updates from Zhang Rui: - Fix a deadlock regression in thermal core framework, which was introduced in 5.3 (Wei Wang) - Initialize thermal control framework earlier to enable thermal mitigation during boot (Amit Kucheria) - Convert the Intelligent Power Allocator (IPA) thermal governor to follow the generic PM_EM instead of its own Energy Model (Quentin Perret) - Introduce a new Amlogic soc thermal driver (Guillaume La Roque) - Add interrupt support for tsens thermal driver (Amit Kucheria) - Add support for MSM8956/8976 in tsens thermal driver (AngeloGioacchino Del Regno) - Add support for r8a774b1 in rcar thermal driver (Biju Das) - Add support for Thermal Monitor Unit v2 in qoriq thermal driver (Yuantian Tang) - Some other fixes/cleanups on thermal core framework and soc thermal drivers (Colin Ian King, Daniel Lezcano, Hsin-Yi Wang, Tian Tao) * 'thermal/next' of git://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux: (32 commits) thermal: Fix deadlock in thermal thermal_zone_device_check thermal: cpu_cooling: Migrate to using the EM framework thermal: cpu_cooling: Make the power-related code depend on IPA PM / EM: Declare EM data types unconditionally arm64: defconfig: Enable CONFIG_ENERGY_MODEL drivers: thermal: tsens: fix potential integer overflow on multiply thermal: cpu_cooling: Reorder the header file thermal: cpu_cooling: Remove pointless dependency on CONFIG_OF thermal: no need to set .owner when using module_platform_driver thermal: qcom: tsens-v1: Fix kfree of a non-pointer value cpufreq: qcom-hw: Move driver initialization earlier clk: qcom: Initialize clock drivers earlier cpufreq: Initialize cpufreq-dt driver earlier cpufreq: Initialize the governors in core_initcall thermal: Initialize thermal subsystem earlier thermal: Remove netlink support dt: thermal: tsens: Document compatible for MSM8976/56 thermal: qcom: tsens-v1: Add support for MSM8956 and MSM8976 MAINTAINERS: add entry for Amlogic Thermal driver thermal: amlogic: Add thermal driver to support G12 SoCs ...
2019-11-30Merge tag 'notifications-pipe-prep-20191115' of ↵Linus Torvalds1-10/+27
git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs Pull pipe rework from David Howells: "This is my set of preparatory patches for building a general notification queue on top of pipes. It makes a number of significant changes: - It removes the nr_exclusive argument from __wake_up_sync_key() as this is always 1. This prepares for the next step: - Adds wake_up_interruptible_sync_poll_locked() so that poll can be woken up from a function that's holding the poll waitqueue spinlock. - Change the pipe buffer ring to be managed in terms of unbounded head and tail indices rather than bounded index and length. This means that reading the pipe only needs to modify one index, not two. - A selection of helper functions are provided to query the state of the pipe buffer, plus a couple to apply updates to the pipe indices. - The pipe ring is allowed to have kernel-reserved slots. This allows many notification messages to be spliced in by the kernel without allowing userspace to pin too many pages if it writes to the same pipe. - Advance the head and tail indices inside the pipe waitqueue lock and use wake_up_interruptible_sync_poll_locked() to poke poll without having to take the lock twice. - Rearrange pipe_write() to preallocate the buffer it is going to write into and then drop the spinlock. This allows kernel notifications to then be added the ring whilst it is filling the buffer it allocated. The read side is stalled because the pipe mutex is still held. - Don't wake up readers on a pipe if there was already data in it when we added more. - Don't wake up writers on a pipe if the ring wasn't full before we removed a buffer" * tag 'notifications-pipe-prep-20191115' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: pipe: Remove sync on wake_ups pipe: Increase the writer-wakeup threshold to reduce context-switch count pipe: Check for ring full inside of the spinlock in pipe_write() pipe: Remove redundant wakeup from pipe_write() pipe: Rearrange sequence in pipe_write() to preallocate slot pipe: Conditionalise wakeup in pipe_read() pipe: Advance tail pointer inside of wait spinlock in pipe_read() pipe: Allow pipes to have kernel-reserved slots pipe: Use head and tail pointers for the ring, not cursor and length Add wake_up_interruptible_sync_poll_locked() Remove the nr_exclusive argument from __wake_up_sync_key() pipe: Reduce #inclusion of pipe_fs_i.h
2019-11-26Merge tag 'pm-5.5-rc1' of ↵Linus Torvalds1-9/+15
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management updates from Rafael Wysocki: "These include cpuidle changes to use nanoseconds (instead of microseconds) as the unit of time and to simplify checks for disabled idle states in the idle loop, some cpuidle fixes and governor updates, assorted cpufreq updates (driver updates mostly and a few core fixes and cleanups), devfreq updates (dominated by the tegra30 driver changes), new CPU IDs for the RAPL power capping driver, relatively minor updates of the generic power domains (genpd) and operation performance points (OPP) frameworks, and assorted fixes and cleanups. There are also two maintainer information updates: Chanwoo Choi will be maintaining the devfreq subsystem going forward and Todd Brandt is going to maintain the pm-graph utility (created by him). Specifics: - Use nanoseconds (instead of microseconds) as the unit of time in the cpuidle core and simplify checks for disabled idle states in the idle loop (Rafael Wysocki) - Fix and clean up the teo cpuidle governor (Rafael Wysocki) - Fix the cpuidle registration error code path (Zhenzhong Duan) - Avoid excessive vmexits in the ACPI cpuidle driver (Yin Fengwei) - Extend the idle injection infrastructure to be able to measure the requested duration in nanoseconds and to allow an exit latency limit for idle states to be specified (Daniel Lezcano) - Fix cpufreq driver registration and clarify a comment in the cpufreq core (Viresh Kumar) - Add NULL checks to the show() and store() methods of sysfs attributes exposed by cpufreq (Kai Shen) - Update cpufreq drivers: * Fix for a plain int as pointer warning from sparse in intel_pstate (Jamal Shareef) * Fix for a hardcoded number of CPUs and stack bloat in the powernv driver (John Hubbard) * Updates to the ti-cpufreq driver and DT files to support new platforms and migrate bindings from opp-v1 to opp-v2 (Adam Ford, H. Nikolaus Schaller) * Merging of the arm_big_little and vexpress-spc drivers and related cleanup (Sudeep Holla) * Fix for imx's default speed grade value (Anson Huang) * Minor cleanup of the s3c64xx driver (Nathan Chancellor) * CPU speed bin detection fix for sun50i (Ondrej Jirman) - Appoint Chanwoo Choi as the new devfreq maintainer. - Update the devfreq core: * Check NULL governor in available_governors_show sysfs to prevent showing wrong governor information and fix a race condition between devfreq_update_status() and trans_stat_show() (Leonard Crestez) * Add new 'interrupt-driven' flag for devfreq governors to allow interrupt-driven governors to prevent the devfreq core from polling devices for status (Dmitry Osipenko) * Improve an error message in devfreq_add_device() (Matthias Kaehlcke) - Update devfreq drivers: * tegra30 driver fixes and cleanups (Dmitry Osipenko) * Removal of unused property from dt-binding documentation for the exynos-bus driver (Kamil Konieczny) * exynos-ppmu cleanup and DT bindings update (Lukasz Luba, Marek Szyprowski) - Add new CPU IDs for CometLake Mobile and Desktop to the Intel RAPL power capping driver (Zhang Rui) - Allow device initialization in the generic power domains (genpd) framework to be more straightforward and clean it up (Ulf Hansson) - Add support for adjusting OPP voltages at run time to the OPP framework (Stephen Boyd) - Avoid freeing memory that has never been allocated in the hibernation core (Andy Whitcroft) - Clean up function headers in a header file and coding style in the wakeup IRQs handling code (Ulf Hansson, Xiaofei Tan) - Clean up the SmartReflex adaptive voltage scaling (AVS) driver for ARM (Ben Dooks, Geert Uytterhoeven) - Wrap power management documentation to fit in 80 columns (Bjorn Helgaas) - Add pm-graph utility entry to MAINTAINERS (Todd Brandt) - Update the cpupower utility: * Fix the handling of set and info subcommands (Abhishek Goel) * Fix build warnings (Nathan Chancellor) * Improve mperf_monitor handling (Janakarajan Natarajan)" * tag 'pm-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (83 commits) PM: Wrap documentation to fit in 80 columns cpuidle: Pass exit latency limit to cpuidle_use_deepest_state() cpuidle: Allow idle injection to apply exit latency limit cpuidle: Introduce cpuidle_driver_state_disabled() for driver quirks cpuidle: teo: Avoid code duplication in conditionals cpufreq: Register drivers only after CPU devices have been registered cpuidle: teo: Avoid using "early hits" incorrectly cpuidle: teo: Exclude cpuidle overhead from computations PM / Domains: Convert to dev_to_genpd_safe() in genpd_syscore_switch() mmc: tmio: Avoid boilerplate code in ->runtime_suspend() PM / Domains: Implement the ->start() callback for genpd PM / Domains: Introduce dev_pm_domain_start() ARM: OMAP2+: SmartReflex: add omap_sr_pdata definition PM / wakeirq: remove unnecessary parentheses power: avs: smartreflex: Remove superfluous cast in debugfs_create_file() call cpuidle: Use nanoseconds as the unit of time PM / OPP: Support adjusting OPP voltages at runtime PM / core: Clean up some function headers in power.h cpufreq: Add NULL checks to show() and store() methods of cpufreq cpufreq: intel_pstate: Fix plain int as pointer warning from sparse ...
2019-11-26Merge branch 'locking-core-for-linus' of ↵Linus Torvalds1-1/+1
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 comprehensive rewrite of the robust/PI futex code's exit handling to fix various exit races. (Thomas Gleixner et al) - Rework the generic REFCOUNT_FULL implementation using atomic_fetch_* operations so that the performance impact of the cmpxchg() loops is mitigated for common refcount operations. With these performance improvements the generic implementation of refcount_t should be good enough for everybody - and this got confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. (Will Deacon) - Other misc changes, fixes, cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) lkdtm: Remove references to CONFIG_REFCOUNT_FULL locking/refcount: Remove unused 'refcount_error_report()' function locking/refcount: Consolidate implementations of refcount_t locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions locking/refcount: Move saturation warnings out of line locking/refcount: Improve performance of generic REFCOUNT_FULL code locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header locking/refcount: Remove unused refcount_*_checked() variants locking/refcount: Ensure integer operands are treated as signed locking/refcount: Define constants for saturation and max refcount values futex: Prevent exit livelock futex: Provide distinct return value when owner is exiting futex: Add mutex around futex exit futex: Provide state handling for exec() as well futex: Sanitize exit state handling futex: Mark the begin of futex exit explicitly futex: Set task::futex_state to DEAD right after handling futex exit futex: Split futex_mm_release() for exit/exec exit/exec: Seperate mm_release() futex: Replace PF_EXITPIDONE with a state ...
2019-11-26Merge branch 'sched-core-for-linus' of ↵Linus Torvalds10-639/+1172
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The biggest changes in this cycle were: - Make kcpustat vtime aware (Frederic Weisbecker) - Rework the CFS load_balance() logic (Vincent Guittot) - Misc cleanups, smaller enhancements, fixes. The load-balancing rework is the most intrusive change: it replaces the old heuristics that have become less meaningful after the introduction of the PELT metrics, with a grounds-up load-balancing algorithm. As such it's not really an iterative series, but replaces the old load-balancing logic with the new one. We hope there are no performance regressions left - but statistically it's highly probable that there *is* going to be some workload that is hurting from these chnages. If so then we'd prefer to have a look at that workload and fix its scheduling, instead of reverting the changes" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (46 commits) rackmeter: Use vtime aware kcpustat accessor leds: Use all-in-one vtime aware kcpustat accessor cpufreq: Use vtime aware kcpustat accessors for user time procfs: Use all-in-one vtime aware kcpustat accessor sched/vtime: Bring up complete kcpustat accessor sched/cputime: Support other fields on kcpustat_field() sched/cpufreq: Move the cfs_rq_util_change() call to cpufreq_update_util() sched/fair: Add comments for group_type and balancing at SD_NUMA level sched/fair: Fix rework of find_idlest_group() sched/uclamp: Fix overzealous type replacement sched/Kconfig: Fix spelling mistake in user-visible help text sched/core: Further clarify sched_class::set_next_task() sched/fair: Use mul_u32_u32() sched/core: Simplify sched_class::pick_next_task() sched/core: Optimize pick_next_task() sched/core: Make pick_next_task_idle() more consistent sched/fair: Better document newidle_balance() leds: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM cpufreq: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM procfs: Use vtime aware kcpustat accessor to fetch CPUTIME_SYSTEM ...
2019-11-26Merge branch 'pm-cpuidle'Rafael J. Wysocki1-9/+15
* pm-cpuidle: cpuidle: Pass exit latency limit to cpuidle_use_deepest_state() cpuidle: Allow idle injection to apply exit latency limit cpuidle: Introduce cpuidle_driver_state_disabled() for driver quirks cpuidle: teo: Avoid code duplication in conditionals cpuidle: teo: Avoid using "early hits" incorrectly cpuidle: teo: Exclude cpuidle overhead from computations cpuidle: Use nanoseconds as the unit of time cpuidle: Consolidate disabled state checks ACPI: processor_idle: Skip dummy wait if kernel is in guest cpuidle: Do not unset the driver if it is there already cpuidle: teo: Fix "early hits" handling for disabled idle states cpuidle: teo: Consider hits and misses metrics of disabled states cpuidle: teo: Rename local variable in teo_select() cpuidle: teo: Ignore disabled idle states that are too deep
2019-11-25Merge tag 'for-5.5/io_uring-20191121' of git://git.kernel.dk/linux-blockLinus Torvalds1-4/+12
Pull io_uring updates from Jens Axboe: "A lot of stuff has been going on this cycle, with improving the support for networked IO (and hence unbounded request completion times) being one of the major themes. There's been a set of fixes done this week, I'll send those out as well once we're certain we're fully happy with them. This contains: - Unification of the "normal" submit path and the SQPOLL path (Pavel) - Support for sparse (and bigger) file sets, and updating of those file sets without needing to unregister/register again. - Independently sized CQ ring, instead of just making it always 2x the SQ ring size. This makes it more flexible for networked applications. - Support for overflowed CQ ring, never dropping events but providing backpressure on submits. - Add support for absolute timeouts, not just relative ones. - Support for generic cancellations. This divorces io_uring from workqueues as well, which additionally gets us one step closer to generic async system call support. - With cancellations, we can support grabbing the process file table as well, just like we do mm context. This allows support for system calls that create file descriptors, like accept4() support that's built on top of that. - Support for io_uring tracing (Dmitrii) - Support for linked timeouts. These abort an operation if it isn't completed by the time noted in the linke timeout. - Speedup tracking of poll requests - Various cleanups making the coder easier to follow (Jackie, Pavel, Bob, YueHaibing, me) - Update MAINTAINERS with new io_uring list" * tag 'for-5.5/io_uring-20191121' of git://git.kernel.dk/linux-block: (64 commits) io_uring: make POLL_ADD/POLL_REMOVE scale better io-wq: remove now redundant struct io_wq_nulls_list io_uring: Fix getting file for non-fd opcodes io_uring: introduce req_need_defer() io_uring: clean up io_uring_cancel_files() io-wq: ensure free/busy list browsing see all items io-wq: ensure we have a stable view of ->cur_work for cancellations io_wq: add get/put_work handlers to io_wq_create() io_uring: check for validity of ->rings in teardown io_uring: fix potential deadlock in io_poll_wake() io_uring: use correct "is IO worker" helper io_uring: fix -ENOENT issue with linked timer with short timeout io_uring: don't do flush cancel under inflight_lock io_uring: flag SQPOLL busy condition to userspace io_uring: make ASYNC_CANCEL work with poll and timeout io_uring: provide fallback request for OOM situations io_uring: convert accept4() -ERESTARTSYS into -EINTR io_uring: fix error clear of ->file_table in io_sqe_files_register() io_uring: separate the io_free_req and io_free_req_find_next interface io_uring: keep io_put_req only responsible for release and put req ...
2019-11-21sched/vtime: Bring up complete kcpustat accessorFrederic Weisbecker1-20/+116
Many callsites want to fetch the values of system, user, user_nice, guest or guest_nice kcpustat fields altogether or at least a pair of these. In that case calling kcpustat_field() for each requested field brings unecessary overhead when we could fetch all of them in a row. So provide kcpustat_cpu_fetch() that fetches the whole kcpustat array in a vtime safe way under the same RCU and seqcount block. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Link: https://lkml.kernel.org/r/20191121024430.19938-3-frederic@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-21sched/cputime: Support other fields on kcpustat_field()Frederic Weisbecker1-11/+43
Provide support for user, nice, guest and guest_nice fields through kcpustat_field(). Whether we account the delta to a nice or not nice field is decided on top of the nice value snapshot taken at the time we call kcpustat_field(). If the nice value of the task has been changed since the last vtime update, we may have inacurrate distribution of the nice VS unnice cputime. However this is considered as a minor issue compared to the proper fix that would involve interrupting the target on nice updates, which is undesired on nohz_full CPUs. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Link: https://lkml.kernel.org/r/20191121024430.19938-2-frederic@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-20cpuidle: Pass exit latency limit to cpuidle_use_deepest_state()Daniel Lezcano1-1/+7
Modify cpuidle_use_deepest_state() to take an additional exit latency limit argument to be passed to find_deepest_idle_state() and make cpuidle_idle_call() pass dev->forced_idle_latency_limit_ns to it for forced idle. Suggested-by: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> [ rjw: Rebase and rearrange code, subject & changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-11-20cpuidle: Allow idle injection to apply exit latency limitDaniel Lezcano1-7/+7
In some cases it may be useful to specify an exit latency limit for the idle state to be used during CPU idle time injection. Instead of duplicating the information in struct cpuidle_device or propagating the latency limit in the call stack, replace the use_deepest_state field with forced_latency_limit_ns to represent that limit, so that the deepest idle state with exit latency within that limit is forced (i.e. no governors) when it is set. A zero exit latency limit for forced idle means to use governors in the usual way (analogous to use_deepest_state equal to "false" before this change). Additionally, add play_idle_precise() taking two arguments, the duration of forced idle and the idle state exit latency limit, both in nanoseconds, and redefine play_idle() as a wrapper around that new function. This change is preparatory, no functional impact is expected. Suggested-by: Rafael J. Wysocki <rafael@kernel.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> [ rjw: Subject, changelog, cpuidle_use_deepest_state() kerneldoc, whitespace ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-11-18sched/cpufreq: Move the cfs_rq_util_change() call to cpufreq_update_util()Vincent Guittot1-49/+62
update_cfs_rq_load_avg() calls cfs_rq_util_change() every time PELT decays, which might be inefficient when the cpufreq driver has rate limitation. When a task is attached on a CPU, we have this call path: update_load_avg() update_cfs_rq_load_avg() cfs_rq_util_change -- > trig frequency update attach_entity_load_avg() cfs_rq_util_change -- > trig frequency update The 1st frequency update will not take into account the utilization of the newly attached task and the 2nd one might be discarded because of rate limitation of the cpufreq driver. update_cfs_rq_load_avg() is only called by update_blocked_averages() and update_load_avg() so we can move the call to cfs_rq_util_change/cpufreq_update_util() into these two functions. It's also interesting to note that update_load_avg() already calls cfs_rq_util_change() directly for the !SMP case. This change will also ensure that cpufreq_update_util() is called even when there is no more CFS rq in the leaf_cfs_rq_list to update, but only IRQ, RT or DL PELT signals. [ mingo: Minor updates. ] Reported-by: Doug Smythies <dsmythies@telus.net> Tested-by: Doug Smythies <dsmythies@telus.net> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: juri.lelli@redhat.com Cc: linux-pm@vger.kernel.org Cc: mgorman@suse.de Cc: rostedt@goodmis.org Cc: sargun@sargun.me Cc: srinivas.pandruvada@linux.intel.com Cc: tj@kernel.org Cc: xiexiuqi@huawei.com Cc: xiezhipeng1@huawei.com Fixes: 039ae8bcf7a5 ("sched/fair: Fix O(nr_cgroups) in the load balancing path") Link: https://lkml.kernel.org/r/1574083279-799-1-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-18Merge tag 'v5.4-rc8' into sched/core, to pick up fixes and dependenciesIngo Molnar2-11/+23
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-18sched/fair: Add comments for group_type and balancing at SD_NUMA levelVincent Guittot1-4/+31
Add comments to describe each state of goup_type and to add some details about the load balance at NUMA level. [ Valentin Schneider: Updates to the comments. ] [ mingo: Other updates to the comments. ] Reported-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Acked-by: Valentin Schneider <valentin.schneider@arm.com> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/1573570243-1903-1-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-18sched/fair: Fix rework of find_idlest_group()Vincent Guittot1-7/+84
The task, for which the scheduler looks for the idlest group of CPUs, must be discounted from all statistics in order to get a fair comparison between groups. This includes utilization, load, nr_running and idle_cpus. Such unfairness can be easily highlighted with the unixbench execl 1 task. This test continuously call execve() and the scheduler looks for the idlest group/CPU on which it should place the task. Because the task runs on the local group/CPU, the latter seems already busy even if there is nothing else running on it. As a result, the scheduler will always select another group/CPU than the local one. This recovers most of the performance regression on my system from the recent load-balancer rewrite. [ mingo: Minor cleanups. ] Reported-by: kernel test robot <rong.a.chen@intel.com> Tested-by: kernel test robot <rong.a.chen@intel.com> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Morten.Rasmussen@arm.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dietmar.eggemann@arm.com Cc: hdanton@sina.com Cc: parth@linux.ibm.com Cc: pauld@redhat.com Cc: quentin.perret@arm.com Cc: riel@surriel.com Cc: srikar@linux.vnet.ibm.com Cc: valentin.schneider@arm.com Fixes: 57abff067a08 ("sched/fair: Rework find_idlest_group()") Link: https://lkml.kernel.org/r/1571762798-25900-1-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-17sched/uclamp: Fix overzealous type replacementValentin Schneider2-4/+4
Some uclamp helpers had their return type changed from 'unsigned int' to 'enum uclamp_id' by commit 0413d7f33e60 ("sched/uclamp: Always use 'enum uclamp_id' for clamp_id values") but it happens that some do return a value in the [0, SCHED_CAPACITY_SCALE] range, which should really be unsigned int. The affected helpers are uclamp_none(), uclamp_rq_max_value() and uclamp_eff_value(). Fix those up. Note that this doesn't lead to any obj diff using a relatively recent aarch64 compiler (8.3-2019.03). The current code of e.g. uclamp_eff_value() properly returns an 11 bit value (bits_per(1024)) and doesn't seem to do anything funny. I'm still marking this as fixing the above commit to be on the safe side. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Reviewed-by: Qais Yousef <qais.yousef@arm.com> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar.Eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: patrick.bellasi@matbug.net Cc: qperret@google.com Cc: surenb@google.com Cc: tj@kernel.org Fixes: 0413d7f33e60 ("sched/uclamp: Always use 'enum uclamp_id' for clamp_id values") Link: https://lkml.kernel.org/r/20191115103908.27610-1-valentin.schneider@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-15sched/uclamp: Fix incorrect conditionQais Yousef1-1/+1
uclamp_update_active() should perform the update when p->uclamp[clamp_id].active is true. But when the logic was inverted in [1], the if condition wasn't inverted correctly too. [1] https://lore.kernel.org/lkml/20190902073836.GO2369@hirez.programming.kicks-ass.net/ Reported-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Patrick Bellasi <patrick.bellasi@matbug.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: babbe170e053 ("sched/uclamp: Update CPU's refcount on TG's clamp changes") Link: https://lkml.kernel.org/r/20191114211052.15116-1-qais.yousef@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-13sched/pelt: Fix update of blocked PELT orderingVincent Guittot1-9/+20
update_cfs_rq_load_avg() can call cpufreq_update_util() to trigger an update of the frequency. Make sure that RT, DL and IRQ PELT signals have been updated before calling cpufreq. 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: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dietmar.eggemann@arm.com Cc: dsmythies@telus.net Cc: juri.lelli@redhat.com Cc: mgorman@suse.de Cc: rostedt@goodmis.org Fixes: 371bf4273269 ("sched/rt: Add rt_rq utilization tracking") Fixes: 3727e0e16340 ("sched/dl: Add dl_rq utilization tracking") Fixes: 91c27493e78d ("sched/irq: Add IRQ utilization tracking") Link: https://lkml.kernel.org/r/1572434309-32512-1-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-13sched/core: Avoid spurious lock dependenciesPeter Zijlstra1-1/+2
While seemingly harmless, __sched_fork() does hrtimer_init(), which, when DEBUG_OBJETS, can end up doing allocations. This then results in the following lock order: rq->lock zone->lock.rlock batched_entropy_u64.lock Which in turn causes deadlocks when we do wakeups while holding that batched_entropy lock -- as the random code does. Solve this by moving __sched_fork() out from under rq->lock. This is safe because nothing there relies on rq->lock, as also evident from the other __sched_fork() callsite. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qian Cai <cai@lca.pw> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: bigeasy@linutronix.de Cc: cl@linux.com Cc: keescook@chromium.org Cc: penberg@kernel.org Cc: rientjes@google.com Cc: thgarnie@google.com Cc: tytso@mit.edu Cc: will@kernel.org Fixes: b7d5dc21072c ("random: add a spinlock_t to struct batched_entropy") Link: https://lkml.kernel.org/r/20191001091837.GK4536@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11cpuidle: Use nanoseconds as the unit of timeRafael J. Wysocki1-1/+1
Currently, the cpuidle subsystem uses microseconds as the unit of time which (among other things) causes the idle loop to incur some integer division overhead for no clear benefit. In order to allow cpuidle to measure time in nanoseconds, add two new fields, exit_latency_ns and target_residency_ns, to represent the exit latency and target residency of an idle state in nanoseconds, respectively, to struct cpuidle_state and initialize them with the help of the corresponding values in microseconds provided by drivers. Additionally, change cpuidle_governor_latency_req() to return the idle state exit latency constraint in nanoseconds. Also meeasure idle state residency (last_residency_ns in struct cpuidle_device and time_ns in struct cpuidle_driver) in nanoseconds and update the cpuidle core and governors accordingly. However, the menu governor still computes typical intervals in microseconds to avoid integer overflows. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Doug Smythies <dsmythies@telus.net> Tested-by: Doug Smythies <dsmythies@telus.net>
2019-11-11sched/core: Further clarify sched_class::set_next_task()Peter Zijlstra6-11/+17
It turns out there really is something special to the first set_next_task() invocation. In specific the 'change' pattern really should not cause balance callbacks. 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: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Fixes: f95d4eaee6d0 ("sched/{rt,deadline}: Fix set_next_task vs pick_next_task") Link: https://lkml.kernel.org/r/20191108131909.775434698@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11sched/fair: Use mul_u32_u32()Peter Zijlstra1-2/+1
While reading the code I encountered another site where we should be using mul_u32_u32() because GCC just won't take a hint. 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: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: https://lkml.kernel.org/r/20191108131909.717931380@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11sched/core: Simplify sched_class::pick_next_task()Peter Zijlstra7-35/+16
Now that the indirect class call never uses the last two arguments of pick_next_task(), remove them. 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: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: https://lkml.kernel.org/r/20191108131909.660595546@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11sched/core: Optimize pick_next_task()Peter Zijlstra4-5/+8
Ever since we moved the sched_class definitions into their own files, the constant expression {fair,idle}_sched_class.pick_next_task() is not in fact a compile time constant anymore and results in an indirect call (barring LTO). Fix that by exposing pick_next_task_{fair,idle}() directly, this gets rid of the indirect call (and RETPOLINE) on the fast path. Also remove the unlikely() from the idle case, it is in fact /the/ way we select idle -- and that is a very common thing to do. Performance for will-it-scale/sched_yield improves by 2% (as reported by 0-day). 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: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: https://lkml.kernel.org/r/20191108131909.603037345@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11sched/core: Make pick_next_task_idle() more consistentPeter Zijlstra2-4/+5
Only pick_next_task_fair() needs the @prev and @rf argument; these are required to implement the cpu-cgroup optimization. None of the other pick_next_task() methods need this. Make pick_next_task_idle() more consistent. 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: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: https://lkml.kernel.org/r/20191108131909.545730862@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11sched/fair: Better document newidle_balance()Peter Zijlstra1-0/+5
Whilst chasing the pick_next_task() race, there was some confusion about the newidle_balance() return values. Document them. [ mingo: Minor edits. ] 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: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Link: https://lkml.kernel.org/r/20191108131909.488364308@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-11Merge tag 'v5.4-rc7' into sched/core, to pick up fixesIngo Molnar8-97/+129
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-08sched: Fix pick_next_task() vs 'change' pattern racePeter Zijlstra7-58/+112
Commit 67692435c411 ("sched: Rework pick_next_task() slow-path") inadvertly introduced a race because it changed a previously unexplored dependency between dropping the rq->lock and sched_class::put_prev_task(). The comments about dropping rq->lock, in for example newidle_balance(), only mentions the task being current and ->on_cpu being set. But when we look at the 'change' pattern (in for example sched_setnuma()): queued = task_on_rq_queued(p); /* p->on_rq == TASK_ON_RQ_QUEUED */ running = task_current(rq, p); /* rq->curr == p */ if (queued) dequeue_task(...); if (running) put_prev_task(...); /* change task properties */ if (queued) enqueue_task(...); if (running) set_next_task(...); It becomes obvious that if we do this after put_prev_task() has already been called on @p, things go sideways. This is exactly what the commit in question allows to happen when it does: prev->sched_class->put_prev_task(rq, prev, rf); if (!rq->nr_running) newidle_balance(rq, rf); The newidle_balance() call will drop rq->lock after we've called put_prev_task() and that allows the above 'change' pattern to interleave and mess up the state. Furthermore, it turns out we lost the RT-pull when we put the last DL task. Fix both problems by extracting the balancing from put_prev_task() and doing a multi-class balance() pass before put_prev_task(). Fixes: 67692435c411 ("sched: Rework pick_next_task() slow-path") Reported-by: Quentin Perret <qperret@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Quentin Perret <qperret@google.com> Tested-by: Valentin Schneider <valentin.schneider@arm.com>
2019-11-08sched/core: Fix compilation error when cgroup not selectedQais Yousef1-1/+1
When cgroup is disabled the following compilation error was hit kernel/sched/core.c: In function ‘uclamp_update_active_tasks’: kernel/sched/core.c:1081:23: error: storage size of ‘it’ isn’t known struct css_task_iter it; ^~ kernel/sched/core.c:1084:2: error: implicit declaration of function ‘css_task_iter_start’; did you mean ‘__sg_page_iter_start’? [-Werror=implicit-function-declaration] css_task_iter_start(css, 0, &it); ^~~~~~~~~~~~~~~~~~~ __sg_page_iter_start kernel/sched/core.c:1085:14: error: implicit declaration of function ‘css_task_iter_next’; did you mean ‘__sg_page_iter_next’? [-Werror=implicit-function-declaration] while ((p = css_task_iter_next(&it))) { ^~~~~~~~~~~~~~~~~~ __sg_page_iter_next kernel/sched/core.c:1091:2: error: implicit declaration of function ‘css_task_iter_end’; did you mean ‘get_task_cred’? [-Werror=implicit-function-declaration] css_task_iter_end(&it); ^~~~~~~~~~~~~~~~~ get_task_cred kernel/sched/core.c:1081:23: warning: unused variable ‘it’ [-Wunused-variable] struct css_task_iter it; ^~ cc1: some warnings being treated as errors make[2]: *** [kernel/sched/core.o] Error 1 Fix by protetion uclamp_update_active_tasks() with CONFIG_UCLAMP_TASK_GROUP Fixes: babbe170e053 ("sched/uclamp: Update CPU's refcount on TG's clamp changes") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Patrick Bellasi <patrick.bellasi@matbug.net> Cc: Mel Gorman <mgorman@suse.de> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Ben Segall <bsegall@google.com> Link: https://lkml.kernel.org/r/20191105112212.596-1-qais.yousef@arm.com
2019-11-07cpufreq: Initialize the governors in core_initcallAmit Kucheria1-1/+1
Initialize the cpufreq governors earlier to allow for earlier performance control during the boot process. Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Link: https://lore.kernel.org/r/b98eae9b44eb2f034d7f5d12a161f5f831be1eb7.1571656015.git.amit.kucheria@linaro.org
2019-10-31Add wake_up_interruptible_sync_poll_locked()David Howells1-0/+23
Add a wakeup call for a case whereby the caller already has the waitqueue spinlock held. This can be used by pipes to alter the ring buffer indices and issue a wakeup under the same spinlock. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2019-10-29io-wq: small threadpool implementation for io_uringJens Axboe1-4/+12
This adds support for io-wq, a smaller and specialized thread pool implementation. This is meant to replace workqueues for io_uring. Among the reasons for this addition are: - We can assign memory context smarter and more persistently if we manage the life time of threads. - We can drop various work-arounds we have in io_uring, like the async_list. - We can implement hashed work insertion, to manage concurrency of buffered writes without needing a) an extra workqueue, or b) needlessly making the concurrency of said workqueue very low which hurts performance of multiple buffered file writers. - We can implement cancel through signals, for cancelling interruptible work like read/write (or send/recv) to/from sockets. - We need the above cancel for being able to assign and use file tables from a process. - We can implement a more thorough cancel operation in general. - We need it to move towards a syslet/threadlet model for even faster async execution. For that we need to take ownership of the used threads. This list is just off the top of my head. Performance should be the same, or better, at least that's what I've seen in my testing. io-wq supports basic NUMA functionality, setting up a pool per node. io-wq hooks up to the scheduler schedule in/out just like workqueue and uses that to drive the need for more/less workers. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-29sched/kcpustat: Introduce vtime-aware kcpustat accessor for CPUTIME_SYSTEMFrederic Weisbecker1-0/+82
Kcpustat is not correctly supported on nohz_full CPUs. The tick doesn't fire and the cputime therefore doesn't move forward. The issue has shown up after the vanishing of the remaining 1Hz which has made the stall visible. We are solving that with checking the task running on a CPU through RCU and reading its vtime delta that we add to the raw kcpustat values. We make sure that we fetch a coherent raw-kcpustat/vtime-delta couple sequence while checking that the CPU referred by the target vtime is the correct one, under the locked vtime seqcount. Only CPUTIME_SYSTEM is handled here as a start because it's the trivial case. User and guest time will require more preparation work to correctly handle niceness. Reported-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpengli@tencent.com> Link: https://lkml.kernel.org/r/20191025020303.19342-1-frederic@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29sched/vtime: Rename vtime_accounting_cpu_enabled() to ↵Frederic Weisbecker1-1/+1
vtime_accounting_enabled_this_cpu() Standardize the naming on top of the vtime_accounting_enabled_*() base. Also make it clear we are checking the vtime state of the *current* CPU with this function. We'll need to add an API to check that state on remote CPUs as well, so we must disambiguate the naming. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rjw@rjwysocki.net> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Link: https://lkml.kernel.org/r/20191016025700.31277-9-frederic@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29sched/cputime: Add vtime guest task stateFrederic Weisbecker1-7/+11
Record guest as a VTIME state instead of guessing it from VTIME_SYS and PF_VCPU. This is going to simplify the cputime read side especially as its state machine is going to further expand in order to fully support kcpustat on nohz_full. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rjw@rjwysocki.net> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Link: https://lkml.kernel.org/r/20191016025700.31277-4-frederic@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29sched/cputime: Add vtime idle task stateFrederic Weisbecker1-5/+8
Record idle as a VTIME state instead of guessing it from VTIME_SYS and is_idle_task(). This is going to simplify the cputime read side especially as its state machine is going to further expand in order to fully support kcpustat on nohz_full. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rjw@rjwysocki.net> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Link: https://lkml.kernel.org/r/20191016025700.31277-3-frederic@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29sched/vtime: Record CPU under seqcount for kcpustat needsFrederic Weisbecker1-0/+3
In order to compute the kcpustat delta on a nohz CPU, we'll need to fetch the task running on that target. Checking that its vtime state snapshot actually refers to the relevant target involves recording that CPU under the seqcount locked on task switch. This is a step toward making kcpustat moving forward on full nohz CPUs. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J . Wysocki <rjw@rjwysocki.net> Cc: Rik van Riel <riel@surriel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Cc: Wanpeng Li <wanpengli@tencent.com> Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com> Link: https://lkml.kernel.org/r/20191016025700.31277-2-frederic@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29sched/fair/util_est: Implement faster ramp-up EWMA on utilization increasesPatrick Bellasi2-1/+14
The estimated utilization for a task: util_est = max(util_avg, est.enqueue, est.ewma) is defined based on: - util_avg: the PELT defined utilization - est.enqueued: the util_avg at the end of the last activation - est.ewma: a exponential moving average on the est.enqueued samples According to this definition, when a task suddenly changes its bandwidth requirements from small to big, the EWMA will need to collect multiple samples before converging up to track the new big utilization. This slow convergence towards bigger utilization values is not aligned to the default scheduler behavior, which is to optimize for performance. Moreover, the est.ewma component fails to compensate for temporarely utilization drops which spans just few est.enqueued samples. To let util_est do a better job in the scenario depicted above, change its definition by making util_est directly follow upward motion and only decay the est.ewma on downward. Signed-off-by: Patrick Bellasi <patrick.bellasi@matbug.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Douglas Raillard <douglas.raillard@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Perret <qperret@google.com> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20191023205630.14469-1-patrick.bellasi@matbug.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29sched/topology: Allow sched_asym_cpucapacity to be disabledValentin Schneider1-1/+5
While the static key is correctly initialized as being disabled, it will remain forever enabled once turned on. This means that if we start with an asymmetric system and hotplug out enough CPUs to end up with an SMP system, the static key will remain set - which is obviously wrong. We should detect this and turn off things like misfit migration and capacity aware wakeups. As Quentin pointed out, having separate root domains makes this slightly trickier. We could have exclusive cpusets that create an SMP island - IOW, the domains within this root domain will not see any asymmetry. This means we can't just disable the key on domain destruction, we need to count how many asymmetric root domains we have. Consider the following example using Juno r0 which is 2+4 big.LITTLE, where two identical cpusets are created: they both span both big and LITTLE CPUs: asym0 asym1 [ ][ ] L L B L L B $ cgcreate -g cpuset:asym0 $ cgset -r cpuset.cpus=0,1,3 asym0 $ cgset -r cpuset.mems=0 asym0 $ cgset -r cpuset.cpu_exclusive=1 asym0 $ cgcreate -g cpuset:asym1 $ cgset -r cpuset.cpus=2,4,5 asym1 $ cgset -r cpuset.mems=0 asym1 $ cgset -r cpuset.cpu_exclusive=1 asym1 $ cgset -r cpuset.sched_load_balance=0 . (the CPU numbering may look odd because on the Juno LITTLEs are CPUs 0,3-5 and bigs are CPUs 1-2) If we make one of those SMP (IOW remove asymmetry) by e.g. hotplugging its big core, we would end up with an SMP cpuset and an asymmetric cpuset - the static key must remain set, because we still have one asymmetric root domain. With the above example, this could be done with: $ echo 0 > /sys/devices/system/cpu/cpu2/online Which would result in: asym0 asym1 [ ][ ] L L B L L When both SMP and asymmetric cpusets are present, all CPUs will observe sched_asym_cpucapacity being set (it is system-wide), but not all CPUs observe asymmetry in their sched domain hierarchy: per_cpu(sd_asym_cpucapacity, <any CPU in asym0>) == <some SD at DIE level> per_cpu(sd_asym_cpucapacity, <any CPU in asym1>) == NULL Change the simple key enablement to an increment, and decrement the key counter when destroying domains that cover asymmetric CPUs. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Dietmar.Eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hannes@cmpxchg.org Cc: lizefan@huawei.com Cc: morten.rasmussen@arm.com Cc: qperret@google.com Cc: tj@kernel.org Cc: vincent.guittot@linaro.org Fixes: df054e8445a4 ("sched/topology: Add static_key for asymmetric CPU capacity optimizations") Link: https://lkml.kernel.org/r/20191023153745.19515-3-valentin.schneider@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-29sched/topology: Don't try to build empty sched domainsValentin Schneider1-1/+4
Turns out hotplugging CPUs that are in exclusive cpusets can lead to the cpuset code feeding empty cpumasks to the sched domain rebuild machinery. This leads to the following splat: Internal error: Oops: 96000004 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 235 Comm: kworker/5:2 Not tainted 5.4.0-rc1-00005-g8d495477d62e #23 Hardware name: ARM Juno development board (r0) (DT) Workqueue: events cpuset_hotplug_workfn pstate: 60000005 (nZCv daif -PAN -UAO) pc : build_sched_domains (./include/linux/arch_topology.h:23 kernel/sched/topology.c:1898 kernel/sched/topology.c:1969) lr : build_sched_domains (kernel/sched/topology.c:1966) Call trace: build_sched_domains (./include/linux/arch_topology.h:23 kernel/sched/topology.c:1898 kernel/sched/topology.c:1969) partition_sched_domains_locked (kernel/sched/topology.c:2250) rebuild_sched_domains_locked (./include/linux/bitmap.h:370 ./include/linux/cpumask.h:538 kernel/cgroup/cpuset.c:955 kernel/cgroup/cpuset.c:978 kernel/cgroup/cpuset.c:1019) rebuild_sched_domains (kernel/cgroup/cpuset.c:1032) cpuset_hotplug_workfn (kernel/cgroup/cpuset.c:3205 (discriminator 2)) process_one_work (./arch/arm64/include/asm/jump_label.h:21 ./include/linux/jump_label.h:200 ./include/trace/events/workqueue.h:114 kernel/workqueue.c:2274) worker_thread (./include/linux/compiler.h:199 ./include/linux/list.h:268 kernel/workqueue.c:2416) kthread (kernel/kthread.c:255) ret_from_fork (arch/arm64/kernel/entry.S:1167) Code: f860dae2 912802d6 aa1603e1 12800000 (f8616853) The faulty line in question is: cap = arch_scale_cpu_capacity(cpumask_first(cpu_map)); and we're not checking the return value against nr_cpu_ids (we shouldn't have to!), which leads to the above. Prevent generate_sched_domains() from returning empty cpumasks, and add some assertion in build_sched_domains() to scream bloody murder if it happens again. The above splat was obtained on my Juno r0 with the following reproducer: $ cgcreate -g cpuset:asym $ cgset -r cpuset.cpus=0-3 asym $ cgset -r cpuset.mems=0 asym $ cgset -r cpuset.cpu_exclusive=1 asym $ cgcreate -g cpuset:smp $ cgset -r cpuset.cpus=4-5 smp $ cgset -r cpuset.mems=0 smp $ cgset -r cpuset.cpu_exclusive=1 smp $ cgset -r cpuset.sched_load_balance=0 . $ echo 0 > /sys/devices/system/cpu/cpu4/online $ echo 0 > /sys/devices/system/cpu/cpu5/online Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dietmar.Eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hannes@cmpxchg.org Cc: lizefan@huawei.com Cc: morten.rasmussen@arm.com Cc: qperret@google.com Cc: tj@kernel.org Cc: vincent.guittot@linaro.org Fixes: 05484e098448 ("sched/topology: Add SD_ASYM_CPUCAPACITY flag detection") Link: https://lkml.kernel.org/r/20191023153745.19515-2-valentin.schneider@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-23Remove the nr_exclusive argument from __wake_up_sync_key()David Howells1-10/+4
Remove the nr_exclusive argument from __wake_up_sync_key() and derived functions as everything seems to set it to 1. Note also that if it wasn't set to 1, it would clear WF_SYNC anyway. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2019-10-21sched/fair: Rework find_idlest_group()Vincent Guittot1-128/+256
The slow wake up path computes per sched_group statisics to select the idlest group, which is quite similar to what load_balance() is doing for selecting busiest group. Rework find_idlest_group() to classify the sched_group and select the idlest one following the same steps as load_balance(). Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten.Rasmussen@arm.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hdanton@sina.com Cc: parth@linux.ibm.com Cc: pauld@redhat.com Cc: quentin.perret@arm.com Cc: riel@surriel.com Cc: srikar@linux.vnet.ibm.com Cc: valentin.schneider@arm.com Link: https://lkml.kernel.org/r/1571405198-27570-12-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-21sched/fair: Optimize find_idlest_group()Vincent Guittot1-36/+14
find_idlest_group() now reads CPU's load_avg in two different ways. Consolidate the function to read and use load_avg only once and simplify the algorithm to only look for the group with lowest load_avg. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten.Rasmussen@arm.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hdanton@sina.com Cc: parth@linux.ibm.com Cc: pauld@redhat.com Cc: quentin.perret@arm.com Cc: riel@surriel.com Cc: srikar@linux.vnet.ibm.com Cc: valentin.schneider@arm.com Link: https://lkml.kernel.org/r/1571405198-27570-11-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-21sched/fair: Use load instead of runnable load in wakeup pathVincent Guittot1-10/+10
Runnable load was originally introduced to take into account the case where blocked load biases the wake up path which may end to select an overloaded CPU with a large number of runnable tasks instead of an underutilized CPU with a huge blocked load. Tha wake up path now starts looking for idle CPUs before comparing runnable load and it's worth aligning the wake up path with the load_balance() logic. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten.Rasmussen@arm.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: hdanton@sina.com Cc: parth@linux.ibm.com Cc: pauld@redhat.com Cc: quentin.perret@arm.com Cc: riel@surriel.com Cc: srikar@linux.vnet.ibm.com Cc: valentin.schneider@arm.com Link: https://lkml.kernel.org/r/1571405198-27570-10-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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