user/sven/linux.git/kernel/sched/core.c, branch v5.9.8

sched/features: Fix !CONFIG_JUMP_LABEL case

2020-10-29T09:12:07Z

[ Upstream commit a73f863af4ce9730795eab7097fb2102e6854365 ] Commit: 765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds") made sched features static for !CONFIG_SCHED_DEBUG configurations, but overlooked the CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL cases. For the latter echoing changes to /sys/kernel/debug/sched_features has the nasty effect of effectively changing what sched_features reports, but without actually changing the scheduler behaviour (since different translation units get different sysctl_sched_features). Fix CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL configurations by properly restructuring ifdefs. Fixes: 765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds") Co-developed-by: Daniel Bristot de Oliveira Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Juri Lelli Signed-off-by: Ingo Molnar Acked-by: Patrick Bellasi Reviewed-by: Valentin Schneider Link: https://lore.kernel.org/r/20201013053114.160628-1-juri.lelli@redhat.com Signed-off-by: Sasha Levin

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59Z

Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva

Merge tag 'sched-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-15T17:36:40Z

Pull scheduler fixes from Ingo Molnar: "Two fixes: fix a new tracepoint's output value, and fix the formatting of show-state syslog printouts" * tag 'sched-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/debug: Fix the alignment of the show-state debug output sched: Fix use of count for nr_running tracepoint

sched/debug: Fix the alignment of the show-state debug output

2020-08-14T10:36:18Z

Current sysrq(t) output task fields name are not aligned with actual task fields value, e.g.: kernel: sysrq: Show State kernel: task PC stack pid father kernel: systemd S12456 1 0 0x00000000 kernel: Call Trace: kernel: ? __schedule+0x240/0x740 To make it more readable, print fields name together with task fields value in the same line, with fixed width: kernel: sysrq: Show State kernel: task:systemd state:S stack:12920 pid: 1 ppid: 0 flags:0x00000000 kernel: Call Trace: kernel: __schedule+0x282/0x620 Signed-off-by: Libing Zhou Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200814030236.37835-1-libing.zhou@nokia-sbell.com

Merge tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-06T18:55:43Z

Pull sched/fifo updates from Ingo Molnar: "This adds the sched_set_fifo*() encapsulation APIs to remove static priority level knowledge from non-scheduler code. The three APIs for non-scheduler code to set SCHED_FIFO are: - sched_set_fifo() - sched_set_fifo_low() - sched_set_normal() These are two FIFO priority levels: default (high), and a 'low' priority level, plus sched_set_normal() to set the policy back to non-SCHED_FIFO. Since the changes affect a lot of non-scheduler code, we kept this in a separate tree" * tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) sched,tracing: Convert to sched_set_fifo() sched: Remove sched_set_*() return value sched: Remove sched_setscheduler*() EXPORTs sched,psi: Convert to sched_set_fifo_low() sched,rcutorture: Convert to sched_set_fifo_low() sched,rcuperf: Convert to sched_set_fifo_low() sched,locktorture: Convert to sched_set_fifo() sched,irq: Convert to sched_set_fifo() sched,watchdog: Convert to sched_set_fifo() sched,serial: Convert to sched_set_fifo() sched,powerclamp: Convert to sched_set_fifo() sched,ion: Convert to sched_set_normal() sched,powercap: Convert to sched_set_fifo*() sched,spi: Convert to sched_set_fifo*() sched,mmc: Convert to sched_set_fifo*() sched,ivtv: Convert to sched_set_fifo*() sched,drm/scheduler: Convert to sched_set_fifo*() sched,msm: Convert to sched_set_fifo*() sched,psci: Convert to sched_set_fifo*() sched,drbd: Convert to sched_set_fifo*() ...

Merge tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-03T21:58:38Z

Pull scheduler updates from Ingo Molnar: - Improve uclamp performance by using a static key for the fast path - Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for better power efficiency of RT tasks on battery powered devices. (The default is to maximize performance & reduce RT latencies.) - Improve utime and stime tracking accuracy, which had a fixed boundary of error, which created larger and larger relative errors as the values become larger. This is now replaced with more precise arithmetics, using the new mul_u64_u64_div_u64() helper in math64.h. - Improve the deadline scheduler, such as making it capacity aware - Improve frequency-invariant scheduling - Misc cleanups in energy/power aware scheduling - Add sched_update_nr_running tracepoint to track changes to nr_running - Documentation additions and updates - Misc cleanups and smaller fixes * tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits) sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst sched/doc: Document capacity aware scheduling sched: Document arch_scale_*_capacity() arm, arm64: Fix selection of CONFIG_SCHED_THERMAL_PRESSURE Documentation/sysctl: Document uclamp sysctl knobs sched/uclamp: Add a new sysctl to control RT default boost value sched/uclamp: Fix a deadlock when enabling uclamp static key sched: Remove duplicated tick_nohz_full_enabled() check sched: Fix a typo in a comment sched/uclamp: Remove unnecessary mutex_init() arm, arm64: Select CONFIG_SCHED_THERMAL_PRESSURE sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry arch_topology, sched/core: Cleanup thermal pressure definition trace/events/sched.h: fix duplicated word linux/sched/mm.h: drop duplicated words in comments smp: Fix a potential usage of stale nr_cpus sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal sched: nohz: stop passing around unused "ticks" parameter. sched: Better document ttwu() sched: Add a tracepoint to track rq->nr_running ...

sched/uclamp: Add a new sysctl to control RT default boost value

2020-07-29T11:51:47Z

RT tasks by default run at the highest capacity/performance level. When uclamp is selected this default behavior is retained by enforcing the requested uclamp.min (p->uclamp_req[UCLAMP_MIN]) of the RT tasks to be uclamp_none(UCLAMP_MAX), which is SCHED_CAPACITY_SCALE; the maximum value. This is also referred to as 'the default boost value of RT tasks'. See commit 1a00d999971c ("sched/uclamp: Set default clamps for RT tasks"). On battery powered devices, it is desired to control this default (currently hardcoded) behavior at runtime to reduce energy consumed by RT tasks. For example, a mobile device manufacturer where big.LITTLE architecture is dominant, the performance of the little cores varies across SoCs, and on high end ones the big cores could be too power hungry. Given the diversity of SoCs, the new knob allows manufactures to tune the best performance/power for RT tasks for the particular hardware they run on. They could opt to further tune the value when the user selects a different power saving mode or when the device is actively charging. The runtime aspect of it further helps in creating a single kernel image that can be run on multiple devices that require different tuning. Keep in mind that a lot of RT tasks in the system are created by the kernel. On Android for instance I can see over 50 RT tasks, only a handful of which created by the Android framework. To control the default behavior globally by system admins and device integrator, introduce the new sysctl_sched_uclamp_util_min_rt_default to change the default boost value of the RT tasks. I anticipate this to be mostly in the form of modifying the init script of a particular device. To avoid polluting the fast path with unnecessary code, the approach taken is to synchronously do the update by traversing all the existing tasks in the system. This could race with a concurrent fork(), which is dealt with by introducing sched_post_fork() function which will ensure the racy fork will get the right update applied. Tested on Juno-r2 in combination with the RT capacity awareness [1]. By default an RT task will go to the highest capacity CPU and run at the maximum frequency, which is particularly energy inefficient on high end mobile devices because the biggest core[s] are 'huge' and power hungry. With this patch the RT task can be controlled to run anywhere by default, and doesn't cause the frequency to be maximum all the time. Yet any task that really needs to be boosted can easily escape this default behavior by modifying its requested uclamp.min value (p->uclamp_req[UCLAMP_MIN]) via sched_setattr() syscall. [1] 804d402fb6f6: ("sched/rt: Make RT capacity-aware") Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200716110347.19553-2-qais.yousef@arm.com

sched/uclamp: Fix a deadlock when enabling uclamp static key

2020-07-29T11:51:47Z

The following splat was caught when setting uclamp value of a task: BUG: sleeping function called from invalid context at ./include/linux/percpu-rwsem.h:49 cpus_read_lock+0x68/0x130 static_key_enable+0x1c/0x38 __sched_setscheduler+0x900/0xad8 Fix by ensuring we enable the key outside of the critical section in __sched_setscheduler() Fixes: 46609ce22703 ("sched/uclamp: Protect uclamp fast path code with static key") Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200716110347.19553-4-qais.yousef@arm.com

sched/uclamp: Remove unnecessary mutex_init()

2020-07-25T10:10:36Z

The uclamp_mutex lock is initialized statically via DEFINE_MUTEX(), it is unnecessary to initialize it runtime via mutex_init(). Signed-off-by: Qinglang Miao Signed-off-by: Ingo Molnar Cc: Patrick Bellasi Cc: Peter Zijlstra Cc: Vincent Guittot Cc: Dietmar Eggemann Link: https://lore.kernel.org/r/20200725085629.98292-1-miaoqinglang@huawei.com

sched: Warn if garbage is passed to default_wake_function()

2020-07-24T12:40:25Z

Since the default_wake_function() passes its flags onto try_to_wake_up(), warn if those flags collide with internal values. Given that the supplied flags are garbage, no repair can be done but at least alert the user to the damage they are causing. In the belief that these errors should be picked up during testing, the warning is only compiled in under CONFIG_SCHED_DEBUG. Signed-off-by: Chris Wilson Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/20200723201042.18861-1-chris@chris-wilson.co.uk