Repository files (latest commit first)

Filename	Latest commit message	Latest commit date
Rafael J. Wysocki b7eaf1aab9 cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely ... 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>		2017-03-23 02:12:14 +01:00
..
bpf	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-03-04 17:31:39 -08:00
cgroup	scripts/spelling.txt: add "disble(d)" pattern and fix typo instances	2017-03-09 17:01:09 -08:00
configs	config: android-base: enable hardened usercopy and kernel ASLR	2017-02-27 18:43:46 -08:00
debug	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>	2017-03-02 08:42:34 +01:00
events	scripts/spelling.txt: add "disble(d)" pattern and fix typo instances	2017-03-09 17:01:09 -08:00
gcov
irq	sched/headers: Prepare to move the get_task_struct()/put_task_struct() and related APIs from <linux/sched.h> to <linux/sched/task.h>	2017-03-02 08:42:40 +01:00
livepatch
locking	Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-03-07 14:33:11 -08:00
power	Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-03-03 10:16:38 -08:00
printk	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h>	2017-03-02 08:42:36 +01:00
rcu	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>	2017-03-02 08:42:34 +01:00
sched	cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely	2017-03-23 02:12:14 +01:00
time	cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely	2017-03-23 02:12:14 +01:00
trace	scripts/spelling.txt: add "overide" pattern and fix typo instances	2017-03-09 17:01:09 -08:00
.gitignore
acct.c	sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>	2017-03-02 08:42:39 +01:00
async.c
audit.c	Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit	2017-02-21 13:25:50 -08:00
audit.h	Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit	2017-02-21 13:25:50 -08:00
audit_fsnotify.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2016-12-17 18:44:00 -08:00
audit_tree.c	Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit	2017-01-05 23:06:06 -08:00
audit_watch.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2016-12-17 18:44:00 -08:00
auditfilter.c
auditsc.c	Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit	2017-02-21 13:25:50 -08:00
backtracetest.c
bounds.c
capability.c	capability: export has_capability	2017-01-12 07:01:56 -07:00
compat.c	Replace <asm/uaccess.h> with <linux/uaccess.h> globally	2016-12-24 11:46:01 -08:00
configs.c	Replace <asm/uaccess.h> with <linux/uaccess.h> globally	2016-12-24 11:46:01 -08:00
context_tracking.c
cpu.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>	2017-03-02 08:42:35 +01:00
cpu_pm.c
crash_dump.c
cred.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h>	2017-03-02 08:42:28 +01:00
delayacct.c	sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>	2017-03-02 08:42:39 +01:00
dma.c
elfcore.c
exec_domain.c
exit.c	userfaultfd: non-cooperative: rollback userfaultfd_exit	2017-03-09 17:01:09 -08:00
extable.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2017-02-22 10:15:09 -08:00
fork.c	sched/headers, RCU: Move rcu_copy_process() from <linux/sched/task.h> to kernel/fork.c	2017-03-03 01:43:46 +01:00
freezer.c
futex.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h>	2017-03-02 08:42:28 +01:00
futex_compat.c	Replace <asm/uaccess.h> with <linux/uaccess.h> globally	2016-12-24 11:46:01 -08:00
groups.c	Replace <asm/uaccess.h> with <linux/uaccess.h> globally	2016-12-24 11:46:01 -08:00
hung_task.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>	2017-03-02 08:42:34 +01:00
irq_work.c
jump_label.c	This release has no new tracing features, just clean ups, minor fixes	2017-02-27 13:26:17 -08:00
kallsyms.c	bpf: make jited programs visible in traces	2017-02-17 13:40:05 -05:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c	kcov: make kcov work properly with KASLR enabled	2016-12-20 09:48:47 -08:00
kexec.c
kexec_core.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk	2017-02-22 17:33:34 -08:00
kexec_file.c	kexec, x86/purgatory: Unbreak it and clean it up	2017-03-10 20:55:09 +01:00
kexec_internal.h	kexec, x86/purgatory: Unbreak it and clean it up	2017-03-10 20:55:09 +01:00
kmod.c	sched/headers, vfs/execve: Prepare to move the do_execve*() prototypes from <linux/sched.h> to <linux/binfmts.h>	2017-03-02 08:42:39 +01:00
kprobes.c	powerpc updates for 4.11 part 1.	2017-02-22 10:30:38 -08:00
ksysfs.c	kernel/ksysfs.c: add __ro_after_init to bin_attribute structure	2017-02-24 17:46:56 -08:00
kthread.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>	2017-03-02 08:42:35 +01:00
latencytop.c	sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>	2017-03-02 08:42:39 +01:00
Makefile	cgroup: move cgroup files under kernel/cgroup/	2016-12-27 14:49:05 -05:00
membarrier.c	Fix: Disable sys_membarrier when nohz_full is enabled	2017-01-23 11:32:16 -08:00
memremap.c	mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}	2017-02-24 17:46:53 -08:00
module-internal.h
module.c	Modules updates for v4.11	2017-02-22 17:08:33 -08:00
module_signing.c
notifier.c	kernel/notifier.c: simplify expression	2017-02-24 17:46:56 -08:00
nsproxy.c
padata.c
panic.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>	2017-03-02 08:42:34 +01:00
params.c
pid.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>	2017-03-02 08:42:35 +01:00
pid_namespace.c	sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency	2017-03-02 08:42:37 +01:00
profile.c	sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>	2017-03-02 08:42:39 +01:00
ptrace.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>	2017-03-02 08:42:35 +01:00
range.c
reboot.c
relay.c	lib/vsprintf.c: remove %Z support	2017-02-27 18:43:47 -08:00
resource.c
seccomp.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h>	2017-03-02 08:42:36 +01:00
signal.c	sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>	2017-03-02 08:42:39 +01:00
smp.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/idle.h>	2017-03-02 08:42:26 +01:00
smpboot.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>	2017-03-02 08:42:35 +01:00
smpboot.h
softirq.c
stacktrace.c	stacktrace, lockdep: Fix address, newline ugliness	2017-02-08 08:21:31 +01:00
stop_machine.c
sys.c	sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>	2017-03-02 08:42:39 +01:00
sys_ni.c	move aio compat to fs/aio.c	2016-12-22 22:58:37 -05:00
sysctl.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h>	2017-03-02 08:42:28 +01:00
sysctl_binary.c	sysctl: add KERN_CONT to deprecated_sysctl_warning()	2016-12-14 16:04:07 -08:00
task_work.c
taskstats.c
test_kprobes.c
torture.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/clock.h>	2017-03-02 08:42:27 +01:00
tracepoint.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>	2017-03-02 08:42:35 +01:00
tsacct.c	sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>	2017-03-02 08:42:39 +01:00
ucount.c	ucount: Remove the atomicity from ucount->count	2017-03-06 15:26:37 -06:00
uid16.c	sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h>	2017-03-02 08:42:31 +01:00
up.c
user-return-notifier.c
user.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h>	2017-03-02 08:42:29 +01:00
user_namespace.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h>	2017-03-02 08:42:29 +01:00
utsname.c	sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h>	2017-03-02 08:42:38 +01:00
utsname_sysctl.c	sched/headers: Remove <linux/rwsem.h> from <linux/sched.h>	2017-03-03 01:45:36 +01:00
watchdog.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>	2017-03-02 08:42:34 +01:00
watchdog_hld.c	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>	2017-03-02 08:42:34 +01:00
workqueue.c	time: Remove CONFIG_TIMER_STATS	2017-02-10 11:15:08 +01:00
workqueue_internal.h