Advanced Computer Systems Karthik Dantu and Steve Ko

Advanced Computer Systems Karthik Dantu and Steve Ko

Administrivia • Classroom change: Davis 338 A • Please register on Piazza – announcements on Piazza from now on • Homework: clone AOSP repo • Bring your laptop on Friday • Project groups • Grouping – best effort • Projects : New ideas

Resource Accounting in Android Build a kernel module that records resource usage – CPU, memory, sensors • Correlate shared resource usage with process • Module checks with the scheduler on which process is currently active • Assigns currently used resources to that process • Information available via the /process folder + Classify processes into active, moderate, and light based on usage + Study how to account for asynchronous resources Members: Manish, Divya, Sharath

Crowd-sourced Wifi Mapping Create a wifi-based indoor localization system • Modify wifi driver to put it into monitor mode • Use inertial sensors + wifi signal to locate a person as well as improve the wifi map + Data collection on Phone. Lab + Design algorithm to opportunistically improve wifimap by sampling users at locations where map is sparse Team: Tom, Dipti, Aviral

Battery Simulator in Android Emulator Build a battery simulator to model energy usage in the Android emulator • Modeling/measurement of energy usage of components of a phone • Modify emulator to incorporate energy simulation + Design energy emulator such that energy numbers can be provided at run-time + Hardware-in-the-loop emulation? Members: Anudipa, Harsha, Harish

Record/Replay System for Android • Instrument Dalvik such that it records the interactions it has with lower layers of framework • Have a replay mode where one can replay a previous app execution + Run-time adaption of recorded information? Members: Taeyeon, Aveek, Satyaditya

End-end Connectivity on Phones • Use netfilter to inspect end-end connection variation during switch from Wifi to 3 G • TCP window size • SACK and other options • Suspend connection monitoring during transitions? + Distinguish between congestion due to a narrow pipe, and loss due to transition + Improve performance by being locally aware of the transition without modification to server Team: Shiqin, Carl, Varun

Filesystem Comparison Compare performance of various filesystems (ext 4, reiserfs, jffs 3) on Android platform • Make the root filesystem using various journaling filesystems • See how well each one does on flash Members: Sharath Chandrashekhara, Pratik, Chun

Latency Measurement Mechanism Implement a latency measurement module in the kernel • Take request/response cues from other kernel modules, and compute delay • Also take cues from device drivers • Verify on desktop system by writing a dummy device with known delays + Use latency manager to measure app switch delay Team: Kai, Ruijie, Peng

Concurrency vs Duty Cycling of Shared Resources Build a kernel module that manages shared resources to accommodate energy management policies, and concurrent requests • Disable wakelock usage by userspace • Allow use of shared resources only by requesting a schedule (once, repeat every) • Take the GCD of all app schedules as the duty cycle period + Demonstrate cases where this policy is better and worse Team: Yin, Feng, Chirag

Information Leakage Due to App Permission Model Apps user permissions from classic Unix • Study and understand how resource sharing occurs in this model • Study potential ways to leak information across apps unintentionally in this model + Implement a service that actively detects such leaks at runtime Members: Yan, Ravikanth, Sirak