LCU14 BURLINGAME

PMWG, LCU14

LCU14-102: PMWG Lightning Talks

CPUIdle

CPUfreq

Common Clock Framework

PM-QA

idlestat

powerdebug

Full NO-HZ

Dynamic IRQ affinity

Power-efficient workqueues

Hibernation on ARM

Thermal cooling (cpufreq)

● CPUIdle, CPUfreq, Common Clock Framework

● Power-efficient workqueues (WQ_POWER_EFFICIENT)

● Dynamic IRQ affinity (CLOCK_EVT_FEAT_DYNIRQ)● Considerably reduce “spurious” wakeups in multi-core platforms

● NO-HZ (NO_HZ_FULL)

● Hibernation on ARM● Core Suspend-to-disk support for ARM

● PM functional test-suite: PM-QA

● Tools: idlestat, powerdebug

Are you using any of these?

● Currently● 12 engineers + tech lead● 6 assignees● Taiwan, India, Finland, Sweden, France, US

● Maintainers● cpuidle, arm-soc, clock framework, mmc, clockevents

The Team

The Lightning Talks(Amit, Tuukka, Kevin, Larry, Howard, Mike, Lina, Daniel, Pi-Cheng, Ulf, Lisa, Vincent)

● Role: Tech Lead

● Employer: Linaro● Based: Helsinki, Finland, Mumbai, India,

??? Pune, India ??

● What I do at Linaro:● Manage all PMWG activities● Tools for scheduler & PM analysis

● Talk to me about:● The hacks you put in place to ship product-quality power management on Linux● Tea● Not staying in one place

Amit Kucheria

● Role: Kernel engineer

● Employer: Huawei● Based: Tampere, Finland

● (Office: Helsinki, Finland)

● What I do at Linaro:● Kernel hacking as part of EAS development

● CpuFreq + EAS integration

● Talk to me about:● Theory of selecting an idle state (Computers only, I’m still trying to learn how to R&R)● 1990s pinball games (I’ll do the talking)● Creating compilers or FPGA hacks (Always willing to listen and learn more tricks)

Tuukka Tikkanen

Kevin Hilman● Role: Kernel developer

● Employer: Linaro● Based: Seattle, WA, USA

● What I do at Linaro:● review/extend PM core framework code/patches

● runtime PM, suspend/resume, genpd, idle, etc.

● Automated board farm for upstream kernels● 35+ boards, 80+ boot tests for every new kernel (mainline, -next, stable, LSK, etc.)

● helping bring full upstream PM support to exynos5 (Chromebook2)● maintainer: OMAP PM core, arm-soc (backup)● ARM support for NO_HZ_FULL (full tickless enhancements)

● Talk to me about:● The best beers of the US Pacific Northwest ● Skateboarding, skiing

● Role: Kernel developer

● Employer: Qualcomm● Based: San Diego, CA, USA

● What I do at Linaro:● ARM/ARM64 PM-related kernel functionality (e.g. arm64 NO-HZ support)● idlestat: support for energy model● kernel on chromebook2: debug/tune/enhance kernel (especially EAS-related)

● Talk to me about:● Mathematics (especially number theory)

Larry Bassel

● Role: Engineer

● Employer: Mediatek● Based: Hsinchu, Taiwan

● What I do at Linaro:● idlestat fixing● EAS validation ● Kernel Upstreaming

● Talk to me about:● e.guitar

Howard Chen

● Role: Kernel Hacker

● Employer: Linaro● Based: Los Angeles, California, USA

● … but it changes every year :-)

● What I do at Linaro:● Maintain the common clock framework● General power management patch review

● CPUfreq, Devfreq, use of the clk.h API, etc

● Hack on CPUfreq + scheduler integration for EAS● Maintain a 2nd-tier board farm for boot testing & power regression testing

● Talk to me about:● Whisk(e)y, especially bourbon● Rock climbing● Spear fishing

Mike Turquette

● Role: Kernel Engineer

● Employer: Qualcomm● Based: Boulder, Colorado, USA

● What I do at Linaro:● Upstream Power Management drivers for QCOM chipsets● per-cpu PM QoS framework● Cluster organization and cluster low power modes

● Talk to me about:● Power and Thermal solutions● Energy awareness of scheduler● Road biking, Food, Big Bang, Sci-fi TV

Lina Iyer

● Role: Kernel Engineer

● Employer: Linaro● Based: Toulouse, France

● What I do at Linaro:● Maintainer of the cpuidle drivers for ARM● Maintainer of the clockevents drivers● Energy-aware scheduler and integration with the cpuidle framework● Making the Linux kernel better

● Talk to me about:● Kernel development, upstreaming changes, power management● System programing in userspace

Daniel Lezcano

● Role: Engineer

● Employer: Mediatek● Based: Hsinchu, Taiwan

● What I do at Linaro:● idlestat fixing● CCF in the future

● Talk to me about:● baseball, video games

Pi-Cheng Chen

● Role: Kernel Engineer

● Employer: Linaro● Based: Linaro Lund, Sweden

● What I do at Linaro:● Maintainer of the MMC subsystem.

● Especially contributed to improve the PM support.● The regular stuff, reviewing, discussing, queuing patches, sending PR, etc.

● Runtime PM deployment for ARM SoC● Provide reference platforms, supporting runtime PM and the generic power domain.

● System PM vs runtime PM, PM core, genpd DT support, genpd for ARM SoCs, adopt drivers to runtime PM, PM clk.

● Clock driver maintainer for ux500.

Talk to me about:● Beer, nice food, skiing, sports.

Ulf Hansson

● Role: Engineer

● Employer: Linaro● Based: Seattle, WA, USA

● What I do at Linaro:● Co-maintainer of the PM-QA test suite

● Learning what engineers do in other teamsand mimic them (especially LAVA & QA)

● Talk to me about:● Experiences as Linaro’s first junior engineer● Skydiving

Lisa Nguyen

● Role: Power Management specialist

● Employer: STMicroelectronics● Based: Le Mans, France

● What I do at Linaro:● Work on energy-aware scheduler and related power management enhancements● … more generally on all areas of the kernel that can impact the power consumption● Work on a workload generator tool (based on rt-app)● Play with Chromebook2 and its 8 cores

● Talk to me about:● Inline skating and beers

Vincent Guittot

● Energy-aware scheduling● Power topology representation in the scheduler

● Tighter integration of cpuidle and cpufreq with the scheduler

● Tools to analyse scheduling behaviour and PM impact

● Clock framework● Co-ordinated rate changes

● per-CPU PM-QoS

● Reference runtime PM implementation

● Tools: ● idlestat features to improve reporting

Current work in progress upstream

Plans for this week

● Analysing scheduling behaviour and impact on power management (Tuesday)

● EAS workshop (Thursday)

● Afternoon siesta room: Sandpebble A● Several EAS discussions/deep-dives around upstreaming, validation, benchmarking

● Idlestat: refactoring and merging the energy model code

● PM-QA: new functional tests

Plans for this week

● SHA IDs in upstream kernel● Power-efficient workqueues: cee22a1, 668106

● Example use: d4e1a73 , da72c96● Dynamic IRQ affinity: d2348fb● NO-HZ: b008848, 6c81fe7● Hibernation: 603fb42a

● Git:● PM-QA: https://git.linaro.org/power/pm-qa.git● Idlestat: https://git.linaro.org/power/idlestat.git● Powerdebug: https://git.linaro.org/power/powerdebug.git

Resources

Have a great week!

Thank you

More about Linaro Connect: connect.linaro.org Linaro members: www.linaro.org/membersMore about Linaro: www.linaro.org/about/