linux/kernel
Patrick Bellasi 60daf9c194 sched/uclamp: Add bucket local max tracking
Because of bucketization, different task-specific clamp values are
tracked in the same bucket.  For example, with 20% bucket size and
assuming to have:

  Task1: util_min=25%
  Task2: util_min=35%

both tasks will be refcounted in the [20..39]% bucket and always boosted
only up to 20% thus implementing a simple floor aggregation normally
used in histograms.

In systems with only few and well-defined clamp values, it would be
useful to track the exact clamp value required by a task whenever
possible. For example, if a system requires only 23% and 47% boost
values then it's possible to track the exact boost required by each
task using only 3 buckets of ~33% size each.

Introduce a mechanism to max aggregate the requested clamp values of
RUNNABLE tasks in the same bucket. Keep it simple by resetting the
bucket value to its base value only when a bucket becomes inactive.
Allow a limited and controlled overboosting margin for tasks recounted
in the same bucket.

In systems where the boost values are not known in advance, it is still
possible to control the maximum acceptable overboosting margin by tuning
the number of clamp groups. For example, 20 groups ensure a 5% maximum
overboost.

Remove the rq bucket initialization code since a correct bucket value
is now computed when a task is refcounted into a CPU's rq.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-3-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24 19:23:44 +02:00
..
bpf SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
cgroup Linux 5.2-rc6 2019-06-24 19:19:53 +02:00
configs
debug
dma treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
events
gcov
irq
livepatch This includes the following fixes: 2019-06-15 07:24:11 -10:00
locking treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 436 2019-06-05 17:37:17 +02:00
power sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity() 2019-06-24 19:23:39 +02:00
printk
rcu
sched sched/uclamp: Add bucket local max tracking 2019-06-24 19:23:44 +02:00
time Linux 5.2-rc5 2019-06-17 12:12:27 +02:00
trace Linux 5.2-rc6 2019-06-24 19:19:53 +02:00
.gitignore
acct.c
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audit_fsnotify.c
audit_tree.c
audit_watch.c
audit.c
audit.h
auditfilter.c
auditsc.c
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capability.c
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configs.c
context_tracking.c
cpu_pm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
cpu.c x86/power: Fix 'nosmt' vs hibernation triple fault during resume 2019-06-03 12:02:03 +02:00
crash_core.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230 2019-06-19 17:09:06 +02:00
crash_dump.c
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delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c
extable.c
fail_function.c
fork.c sched/core: Provide a pointer to the valid CPU mask 2019-06-03 11:49:37 +02:00
freezer.c
futex.c
gen_kheaders.sh
groups.c
hung_task.c
iomem.c
irq_work.c
jump_label.c
kallsyms.c
kcmp.c
Kconfig.freezer
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Kconfig.locks
Kconfig.preempt
kcov.c
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kexec_internal.h
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kheaders.c
kmod.c
kprobes.c
ksysfs.c
kthread.c
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Makefile
memremap.c mm/devm_memremap_pages: fix final page put race 2019-06-13 17:34:56 -10:00
module_signing.c
module-internal.h
module.c
notifier.c
nsproxy.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
padata.c
panic.c
params.c
pid_namespace.c
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profile.c
ptrace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2019-06-11 15:44:45 -10:00
range.c
reboot.c
relay.c
resource.c
rseq.c
seccomp.c
signal.c signal: improve comments 2019-06-05 15:06:07 +02:00
smp.c
smpboot.c
smpboot.h
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stackleak.c
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stop_machine.c
sys_ni.c
sys.c
sysctl_binary.c
sysctl.c sysctl: define proc_do_static_key() 2019-06-14 20:18:27 -07:00
task_work.c
taskstats.c
test_kprobes.c
torture.c
tracepoint.c
tsacct.c
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uid16.c
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umh.c
up.c
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user-return-notifier.c
user.c
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watchdog_hld.c
watchdog.c
workqueue_internal.h
workqueue.c