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Juri Lelli 406cbca78c UPSTREAM: cpufreq: schedutil: use now as reference when aggregating shared policy requests 
Currently, sugov_next_freq_shared() uses last_freq_update_time as a
reference to decide when to start considering CPU contributions as
stale.

However, since last_freq_update_time is set by the last CPU that issued
a frequency transition, this might cause problems in certain cases. In
practice, the detection of stale utilization values fails whenever the
CPU with such values was the last to update the policy. For example (and
please note again that the SCHED_CPUFREQ_RT flag is not the problem
here, but only the detection of after how much time that flag has to be
considered stale), suppose a policy with 2 CPUs:

               CPU0                |               CPU1
                                   |
                                   |     RT task scheduled
                                   |     SCHED_CPUFREQ_RT is set
                                   |     CPU1->last_update = now
                                   |     freq transition to max
                                   |     last_freq_update_time = now
                                   |

                        more than TICK_NSEC nsecs

                                   |
     a small CFS wakes up          |
     CPU0->last_update = now1      |
     delta_ns(CPU0) < TICK_NSEC*   |
     CPU0's util is considered     |
     delta_ns(CPU1) =              |
      last_freq_update_time -      |
      CPU1->last_update = 0        |
      < TICK_NSEC                  |
     CPU1 is still considered      |
     CPU1->SCHED_CPUFREQ_RT is set |
     we stay at max (until CPU1    |
     exits from idle)              |

* delta_ns is actually negative as now1 > last_freq_update_time

While last_freq_update_time is a sensible reference for rate limiting,
it doesn't seem to be useful for working around stale CPU states.

Fix the problem by always considering now (time) as the reference for
deciding when CPUs have stale contributions.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit d86ab9cff8)
2017-10-15 23:28:32 +05:30
..
bpf Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-07-22 12:02:06 +08:00
configs kconfig: tinyconfig: provide whole choice blocks to avoid warnings 2016-09-24 10:07:42 +02:00
debug UPSTREAM: module: use a structure to encapsulate layout. 2017-08-11 19:31:04 +05:30
events Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-09-01 13:59:45 +05:30
gcov Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-09-03 12:01:45 +08:00
irq genirq: Release resources in __setup_irq() error path 2017-06-26 07:13:10 +02:00
livepatch livepatch: x86: fix relocation computation with kASLR 2015-11-11 17:36:04 +01:00
locking Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-09-14 12:01:21 +08:00
power Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-10-13 23:14:45 +08:00
printk UPSTREAM: printk: when dumping regs, show the stack, not thread_info 2017-08-11 19:31:04 +05:30
rcu Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2016-12-12 22:17:37 +08:00
sched UPSTREAM: cpufreq: schedutil: use now as reference when aggregating shared policy requests 2017-10-15 23:28:32 +05:30
time Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-10-09 14:32:35 +08:00
trace Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-10-13 23:14:45 +08:00
.gitignore certs: add .gitignore to stop git nagging about x509_certificate_list 2015-10-21 15:18:35 +01:00
acct.c
async.c
audit.c BACKPORT: audit: consistently record PIDs with task_tgid_nr() 2016-10-12 17:34:22 +05:30
audit.h audit: audit_tree_match can be boolean 2015-11-04 08:23:51 -05:00
audit_fsnotify.c audit: clean simple fsnotify implementation 2015-08-06 16:14:53 -04:00
audit_tree.c audit: audit_tree_match can be boolean 2015-11-04 08:23:51 -05:00
audit_watch.c audit: Fix use after free in audit_remove_watch_rule() 2017-08-24 17:02:35 -07:00
auditfilter.c audit: fix comment block whitespace 2015-11-04 08:23:51 -05:00
auditsc.c BACKPORT: audit: consistently record PIDs with task_tgid_nr() 2016-10-12 17:34:22 +05:30
backtracetest.c
bounds.c
capability.c exec: Ensure mm->user_ns contains the execed files 2017-01-06 11:16:14 +01:00
cgroup.c Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-04-23 12:02:14 +08:00
cgroup_freezer.c cgroup: fix handling of multi-destination migration from subtree_control enabling 2015-12-03 10:18:21 -05:00
cgroup_pids.c cgroup_pids: don't account for the root cgroup 2015-12-03 10:18:21 -05:00
compat.c
configs.c
context_tracking.c context_tracking: avoid irq_save/irq_restore on guest entry and exit 2015-11-10 12:06:23 +01:00
cpu.c Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-01-13 12:01:52 +08:00
cpu_pm.c kernel/cpu_pm: fix cpu_cluster_pm_exit comment 2015-09-03 02:42:20 +02:00
cpuset.c Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-10-13 23:14:45 +08:00
crash_dump.c
cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-09-15 08:27:49 +02:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c FIXUP: sched/tune: fix accounting for runnable tasks 2016-09-14 14:59:32 +05:30
extable.c kernel/extable.c: mark core_kernel_text notrace 2017-07-21 07:44:56 +02:00
fork.c BACKPORT: partial: mm, oom_reaper: do not mmput synchronously from the oom reaper context 2017-10-15 23:21:09 +05:30
freezer.c
futex.c Merge tag 'v4.4.56' into linux-linaro-lsk-v4.4 2017-03-23 12:00:54 +08:00
futex_compat.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-02-25 12:01:16 -08:00
groups.c
hung_task.c
irq_work.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
jump_label.c jump_labels: API for flushing deferred jump label updates 2017-01-19 20:17:19 +01:00
kallsyms.c
kcmp.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-02-25 12:01:16 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c kexec: use file name as the output message prefix 2015-11-06 17:50:42 -08:00
kexec_core.c kexec: use file name as the output message prefix 2015-11-06 17:50:42 -08:00
kexec_file.c kexec: fix double-free when failing to relocate the purgatory 2016-09-24 10:07:36 +02:00
kexec_internal.h kexec: split kexec_file syscall code to kexec_file.c 2015-09-10 13:29:01 -07:00
kmod.c kmod: don't run async usermode helper as a child of kworker thread 2015-10-23 17:55:10 +09:00
kprobes.c tracing/kprobes: Enforce kprobes teardown after testing 2017-05-25 14:30:17 +02:00
ksysfs.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
kthread.c UPSTREAM: kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function 2017-08-11 19:31:04 +05:30
latencytop.c
Makefile sys_membarrier(): system-wide memory barrier (generic, x86) 2015-09-11 15:21:34 -07:00
membarrier.c Fix: Disable sys_membarrier when nohz_full is enabled 2017-03-12 06:37:26 +01:00
memremap.c mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done} 2017-01-19 20:17:18 +01:00
module-internal.h
module.c UPSTREAM: modules: fix longstanding /proc/kallsyms vs module insertion race. 2017-08-11 19:31:04 +05:30
module_signing.c KEYS: Merge the type-specific data with the payload data 2015-10-21 15:18:36 +01:00
notifier.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 08:40:25 -07:00
nsproxy.c
padata.c padata: free correct variable 2017-05-20 14:27:02 +02:00
panic.c kernel/panic.c: add missing \n 2017-07-05 14:37:19 +02:00
params.c Nothing exciting, minor tweaks and cleanups. 2015-11-09 15:53:39 -08:00
pid.c pids: make task_tgid_nr_ns() safe 2017-08-24 17:02:36 -07:00
pid_namespace.c pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes 2017-05-25 14:30:11 +02:00
profile.c mm: rename alloc_pages_exact_node() to __alloc_pages_node() 2015-09-08 15:35:28 -07:00
ptrace.c ptrace: Properly initialize ptracer_cred on fork 2017-06-14 13:16:20 +02:00
range.c
reboot.c kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00
relay.c kernel/relay.c: use kvfree() in relay_free_page_array() 2015-06-30 19:44:59 -07:00
resource.c /proc/iomem: only expose physical resource addresses to privileged users 2017-08-06 19:19:42 -07:00
seccomp.c seccomp: fix the usage of get/put_seccomp_filter() in seccomp_get_filter() 2017-10-05 09:41:46 +02:00
signal.c signal: protect SIGNAL_UNKILLABLE from unintentional clearing. 2017-08-11 09:08:59 -07:00
smp.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
smpboot.c stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark() 2015-10-20 10:23:55 +02:00
smpboot.h
softirq.c
stacktrace.c
stop_machine.c kernel: remove stop_machine() Kconfig dependency 2015-12-12 10:15:34 -08:00
sys.c BACKPORT: timer: convert timer_slack_ns from unsigned long to u64 2016-07-11 12:43:04 +05:30
sys_ni.c mm: mlock: add new mlock system call 2015-11-05 19:34:48 -08:00
sysctl.c Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-10-09 14:32:35 +08:00
sysctl_binary.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-04-12 09:08:58 -07:00
task_work.c task_work: remove fifo ordering guarantee 2015-09-05 13:46:58 -07:00
taskstats.c
test_kprobes.c
torture.c torture: Consolidate cond_resched_rcu_qs() into stutter_wait() 2015-10-06 11:25:01 -07:00
tracepoint.c tracepoint: Give priority to probes of tracepoints 2015-10-25 21:33:54 -04:00
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c capabilities: ambient capabilities 2015-09-04 16:54:41 -07:00
utsname.c
utsname_sysctl.c
watchdog.c Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-android 2017-01-09 12:01:35 +08:00
workqueue.c workqueue: implicit ordered attribute should be overridable 2017-08-11 09:09:00 -07:00
workqueue_internal.h