Hi,
This is based of the work done by Steve Muckle [1] before he left Linaro
and most of the patches are still under his authorship. I have done
couple of improvements (detailed in individual patches) and removed the
late callback support [2] as I wasn't sure of the value it adds. We can
include it separately if others feel it is required. This series is
based on pm/linux-next with patches [3] and [4] applied on top of it.
With Android UI and benchmarks the latency of cpufreq response to
certain scheduling events can become very critical. Currently, callbacks
into schedutil are only made from the scheduler if the target CPU of the
event is the same as the current CPU. This means there are certain
situations where a target CPU may not run schedutil for some time.
One testcase to show this behavior is where a task starts running on
CPU0, then a new task is also spawned on CPU0 by a task on CPU1. If the
system is configured such that new tasks should receive maximum demand
initially, this should result in CPU0 increasing frequency immediately.
Because of the above mentioned limitation though this does not occur.
This is verified using ftrace with the sample [5] application.
This patchset updates the scheduler to call cpufreq callbacks for remote
CPUs as well and updates schedutil governor to deal with it. An
additional flag is added to cpufreq policies to avoid sending IPIs to
remote CPUs to update the frequency, if CPUs on the platform can change
frequency of any other CPU.
This series is tested with couple of usecases (Android: hackbench,
recentfling, galleryfling, vellamo, Ubuntu: hackbench) on ARM hikey
board (64 bit octa-core, single policy). Only galleryfling showed minor
improvements, while others didn't had much deviation.
The reason being that this patchset only targets a corner case, where
following are required to be true to improve performance and that
doesn't happen too often with these tests:
- Task is migrated to another CPU.
- The task has maximum demand initially, and should take the CPU to
higher OPPs.
- And the target CPU doesn't call into schedutil until the next tick,
without this patchset.
--
viresh
[1] https://git.linaro.org/people/steve.muckle/kernel.git/log/?h=pmwg-integrati…
[2] https://git.linaro.org/people/steve.muckle/kernel.git/commit/?h=pmwg-integr…
[3] https://marc.info/?l=linux-kernel&m=148766093718487&w=2
[4] https://marc.info/?l=linux-kernel&m=148903231720432&w=2
[5] http://pastebin.com/7LkMSRxE
Steve Muckle (8):
sched: cpufreq: add cpu to update_util_data
irq_work: add irq_work_queue_on for !CONFIG_SMP
sched: cpufreq: extend irq work to support fast switches
sched: cpufreq: remove smp_processor_id() in remote paths
sched: cpufreq: detect, process remote callbacks
cpufreq: governor: support scheduler cpufreq callbacks on remote CPUs
intel_pstate: ignore scheduler cpufreq callbacks on remote CPUs
sched: cpufreq: enable remote sched cpufreq callbacks
Viresh Kumar (1):
cpufreq: Add dvfs_possible_from_any_cpu policy flag
drivers/cpufreq/cpufreq-dt.c | 1 +
drivers/cpufreq/cpufreq_governor.c | 2 +-
drivers/cpufreq/intel_pstate.c | 3 ++
include/linux/cpufreq.h | 9 +++++
include/linux/irq_work.h | 7 ++++
include/linux/sched/cpufreq.h | 1 +
kernel/sched/cpufreq.c | 1 +
kernel/sched/cpufreq_schedutil.c | 80 +++++++++++++++++++++++++++++---------
kernel/sched/fair.c | 6 ++-
kernel/sched/sched.h | 3 +-
10 files changed, 90 insertions(+), 23 deletions(-)
--
2.7.1.410.g6faf27b
Hello,
Your item has arrived at Tue, 11 Apr 2017 05:22:31 +0200, but our courier
was not able to deliver the parcel.
Please check the attachment for details!
Thanks and best regards.
Yevette Mains - USPS Senior Operation Agent.
Hi,
we are only a week away from the OSPM-summit!
Pack your bags (or stay tuned for the live streaming).
Don't forget to subscribe to the summit mailing list to receive updates by
either following the instructions available at the following link
http://groups.google.com/group/ospm-summit-2017/boxsubscribe?email=<your_email>
or sending an email to ospm-summit-2017+subscribe(a)googlegroups.com
Archives are available at https://groups.google.com/forum/#!forum/ospm-summit-2017
More information about schedule and logistics follow.
---
Power Management and Scheduling in the Linux Kernel (OSPM-summit)
April 3-4, 2017
Scuola Superiore Sant'Anna (SSSA)
Pisa, Italy
http://retis.sssup.it/ospm-summit/
---
.:: FOCUS
Power management and scheduling techniques to reduce energy consumption while
meeting performance and latency requirements are receiving considerable
attention from the Linux Kernel development community.
The Power Management and Scheduling in the Linux Kernel (OSPM-summit) summit
aims at fostering further interest and discussion to happen.
.:: SCHEDULE
The summit is organized to cover two days of discussions and talks.
What follows is a tentative schedule, subject to last minute changes.
Find more info and real time updates on this shared document:
https://docs.google.com/spreadsheets/d/1B-IsUIGitvRa7ZzppEAJBMgGpIgRAAnu_Oh…
Monday (2017-04-03)
*******************
09:00AM - 09:30AM Welcome and Introduction (DAY 1)
---
09:30AM - 10:20AM Tooling/LISA
---
10:20AM - 11:10AM About The Need to Power Instrument The Linux Kernel
---
11:10AM - 11:20AM Break
---
11:20AM - 12:10AM What are the latest evolutions in PELT and what next
---
12:10AM - 01:00PM PELT decay clamping/UTIL_EST
---
01:00PM - 02:30PM Lunch
---
02:30PM - 03:20PM EAS where we are
---
03:20PM - 04:10PM Energy model/Exotic topologies
---
04:10PM - 04:20PM Break
---
04:20PM - 05:10PM Schedtune
---
05:10PM - 06:00PM SCHED_DEADLINE and reclaiming
Tuesday (2017-04-04)
********************
09:00AM - 09:30AM Welcome and Introduction (DAY 2)
---
09:30AM - 10:20AM Discussion about possible improvements in the schedutil governor
---
10:20AM - 11:10AM Schedutil for SCHED_DEADLINE
---
11:10AM - 11:20AM Break
---
11:20AM - 12:10AM Parameterizing CFS load balancing: nr_running/util/load
---
12:10AM - 01:00PM Tracepoints for PELT
---
01:00PM - 02:30PM Lunch
---
02:30PM - 03:20PM IRQ prediction
---
03:20PM - 04:10PM I/O scheduling and power management with storage devices
---
04:10PM - 04:20PM Break
---
04:20PM - 05:10PM SCHED_DEADLINE group scheduling
---
05:10PM - 06:00PM A Hierarchical Scheduling Model for Dynamic Soft-Realtime Systems
---
06:00PM - 06:30PM Closing Remarks
We are looking into setting up live streaming of the sessions. Details
will be soon shared through the shared doc mentioned above and the
event mailing list.
List of attendees is also available in the doc and on the event website.
.:: VENUE
The workshop will take place at ReTiS Lab*, Scuola Superiore Sant'Anna, Pisa,
Italy. Pisa is a small town, walking distance from the city center to the venue
is 20 minutes, walking distance from the airport to the city center is 30
minutes. More details are available from the summit web page:
http://retis.sssup.it/ospm-summit/
A map of the town with venue location, points of interest and
transportation information is available at:
https://drive.google.com/open?id=1ANKOXr2cuZkABXskDurgrGdl_js&usp=sharing
Bus from Airport to city centre takes about 10 min and costs 1.20 euros
(2 euros if bought on board). Large bills are usually not accepted.
Taxi from Airport to city centre costs 10/15 euros. Credit cards are not
accepted.
.:: ORGANIZERS (in alphabetical order)
Luca Abeni (SSSA)
Patrick Bellasi (ARM)
Tommaso Cucinotta (SSSA)
Dietmar Eggemann (ARM)
Sudeep Holla (ARM)
Juri Lelli (ARM)
Lorenzo Pieralisi (ARM)
Morten Rasmussen (ARM)
