Quentin Perret b68a4c0dba sched/topology: Disable EAS on inappropriate platforms ...

Energy Aware Scheduling (EAS) in its current form is most relevant on
platforms with asymmetric CPU topologies (e.g. Arm big.LITTLE) since
this is where there is a lot of potential for saving energy through
scheduling. This is particularly true since the Energy Model only
includes the active power costs of CPUs, hence not providing enough data
to compare packing-vs-spreading strategies.

As such, disable EAS on root domains where the SD_ASYM_CPUCAPACITY flag
is not set. While at it, disable EAS on systems where the complexity of
the Energy Model is too high since that could lead to unacceptable
scheduling overhead.

All in all, EAS can be used on a root domain if and only if:
  1. an Energy Model is available;
  2. the root domain has an asymmetric CPU capacity topology;
  3. the complexity of the root domain's EM is low enough to keep
     scheduling overheads low.

Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adharmap@codeaurora.org
Cc: chris.redpath@arm.com
Cc: currojerez@riseup.net
Cc: dietmar.eggemann@arm.com
Cc: edubezval@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: javi.merino@kernel.org
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: morten.rasmussen@arm.com
Cc: patrick.bellasi@arm.com
Cc: pkondeti@codeaurora.org
Cc: rjw@rjwysocki.net
Cc: skannan@codeaurora.org
Cc: smuckle@google.com
Cc: srinivas.pandruvada@linux.intel.com
Cc: thara.gopinath@linaro.org
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Cc: viresh.kumar@linaro.org
Link: https://lkml.kernel.org/r/20181203095628.11858-8-quentin.perret@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2018-12-11 15:17:00 +01:00

..

autogroup.c

sched/autogroup: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]

2018-05-05 08:34:42 +02:00

autogroup.h

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

clock.c

sched/clock: Disable interrupts when calling generic_sched_clock_init()

2018-07-30 19:33:35 +02:00

completion.c

sched/Documentation: Update wake_up() & co. memory-barrier guarantees

2018-07-17 09:30:34 +02:00

core.c

sched: Fix various typos in comments

2018-12-03 11:55:42 +01:00

cpuacct.c

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

cpudeadline.c

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

cpudeadline.h

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

cpufreq_schedutil.c

sched/cpufreq: Prepare schedutil for Energy Aware Scheduling

2018-12-11 15:16:58 +01:00

cpufreq.c

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

cpupri.c

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

cpupri.h

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

cputime.c

sched: Fix various typos in comments

2018-12-03 11:55:42 +01:00

deadline.c

sched/core: Remove unnecessary unlikely() in push_*_task()

2018-12-11 15:16:57 +01:00

debug.c

sched/core: Create task_has_idle_policy() helper

2018-11-12 06:17:52 +01:00

fair.c

sched/topology: Add lowest CPU asymmetry sched_domain level pointer

2018-12-11 15:16:59 +01:00

features.h

sched/fair: Disable LB_BIAS by default

2018-10-02 09:45:01 +02:00

idle.c

x86/stackprotector: Remove the call to boot_init_stack_canary() from cpu_startup_entry()

2018-10-22 04:07:24 +02:00

isolation.c

sched: Fix various typos in comments

2018-12-03 11:55:42 +01:00

loadavg.c

sched: loadavg: make calc_load_n() public

2018-10-26 16:26:32 -07:00

Makefile

psi: pressure stall information for CPU, memory, and IO

2018-10-26 16:26:32 -07:00

membarrier.c

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04 12:39:29 +01:00

pelt.c

sched/fair: Remove setting task's se->runnable_weight during PELT update

2018-10-02 09:45:03 +02:00

pelt.h

sched/pelt: Fix warning and clean up IRQ PELT config

2018-10-02 09:45:00 +02:00

psi.c

psi: make disabling/enabling easier for vendor kernels

2018-11-30 14:56:14 -08:00

rt.c

sched/core: Remove unnecessary unlikely() in push_*_task()

2018-12-11 15:16:57 +01:00

sched-pelt.h

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

2017-11-02 11:10:55 +01:00

sched.h

sched/topology: Add lowest CPU asymmetry sched_domain level pointer

2018-12-11 15:16:59 +01:00

stats.c

proc: introduce proc_create_seq{,_data}

2018-05-16 07:23:35 +02:00

stats.h

psi: make disabling/enabling easier for vendor kernels

2018-11-30 14:56:14 -08:00

stop_task.c

sched: Clean up and harmonize the coding style of the scheduler code base

2018-03-03 15:50:21 +01:00

swait.c

sched/swait: Rename to exclusive

2018-06-20 11:35:56 +02:00

topology.c

sched/topology: Disable EAS on inappropriate platforms

2018-12-11 15:17:00 +01:00

wait_bit.c

sched/wait: Improve __var_waitqueue() code generation

2018-03-20 08:23:25 +01:00

wait.c

sched/wait: assert the wait_queue_head lock is held in __wake_up_common

2018-08-22 10:52:47 -07:00