Usage and Comparisons of Control Group in Android AOSP: Marshmallow and Before
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The document discusses control groups in Android Marshmallow and earlier versions. It summarizes discussions from a 2015 conference about big.LITTLE support in Android and differences between the /dev/cpuctl/ and /dev/cpuset/ control groups. The document also examines how the cpuset control group is used in Android Marshmallow to set CPU affinity for processes and discusses ongoing work to improve real-time task performance using control groups.
Usage and Comparisons of Control Group in Android AOSP: Marshmallow and Before
- 1. Usage and Comparisons of Control Group in Android AOSP: Marshmallow and Before 2016/1/11 Yoshi
- 2. State-of-the-Art • In Seattle on August 20th, 2015 – Topic: big.LITTLE Support in Android • Todd Kjos & Tim Murray from Google Summary of LPC Android microconference http://lwn.net/Articles/657139/
- 5. Question 1: Differences between /dev/cpuctl/ & /dev/cpuset/
- 6. 52/(1024+52) ~= 5% Only bg_non_interactive group is made init.rc @ /alps/system/core/rootdir/
- 7. New cpuset cgroup in init.rc AMS!!
- 8. Reply to Question 1 • Before Android M, we’ve already see bg_non_interactive as a control group – cpuctl is for “% of CPU Usage” • Background = 5% • Foreground = 95% • In Android M, cpuset is another control group for setting big.LITTLE
- 9. Question 2: Does Google Have Similar Concepts of APO? Similar to APO = Interceptions in activityResumed and activityPaused in AMS
- 10. Check Pause and Resume Methods Reply to Q2: Seems nothing special in M
- 11. Question 3: How CPUSET cgroup is used? Find CPUSETS
- 14. Reply to Question 3 • Seems to be used when adjusting Out-of- Memory adjustment – One-time call, not resume/pause every time
- 15. Summary • We went through how new CPUSET is used in AOSP 6.0 • We compared the differences between Google’s idea and APO • Cgroups interface and functionalities are changed by Google (Not presented in the slides) • Partial conventional cgroups in Vanilla’s kernel works – Freezer & vanilla’s cpuset have been tested – Why??
- 16. Ongoing • TOSHIBA’s study on improving real-time tasks’ performance – http://elinux.org/images/8/84/Real- Time_Tasks_Partitioning_using_Cgroups.pdf • Should we consider APO, EAS based on cgroup? • AAF had a meeting for discussing cgroups • SCHED_DEADLINE introduces constant bandwidth server scheduling policy in Linux Kernel 3.14 – Android L uses 3.10 – Android M uses 3.18
- 17. Active Discussion in LPC Android u- Conference (2015/8/20) • Most of the EAS discussion focused on energy – Interactive cpufreq governor in Android is mostly focused on latency • how does latency come into the picture and how can it be controlled? – The schedtune sysfs knob allows for similar boosting » When an event occurs, Android user space could provide some short-term boosting to improve latency response – Riley Andrews from Google noted that the interactive cpufreq governor gives this benefit without user space having to do anything – Lelli pointed out that the governor does it a bit blindly, so this allows a more informed and focused response that could save power » I think the basic concept is the same as APO http://lwn.net/Articles/657139/
- 18. Xiaomi’s Smart CGroup • The new Smart CGroups will distribute the CPU usage of process groups better between cores: so instead of making one core do all the work, the work is divided as balanced as possible to make the processor run as efficient as possible. – http://en.miui.com/thread-35193-1-1.html
- 19. Reference • Binder’s priority propagation – https://github.com/keesj/gomo/wiki/AndroidSche duling • Summary of the LPC Android microconference – http://lwn.net/Articles/657139/ • Google I/O 2015 on cgroup and big.LITTLE – http://www.linuxplumbersconf.org/2015/ocw//sy stem/presentations/3399/original/LPC-tkjos.pdf
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