Y. Charlie Hu
Professor of Electrical and Computer Engineering
Professor of Computer Science (by courtesy)
IEEE Fellow
University Faculty Scholar, Purdue University
(See also the official home page)
Address: Purdue University, School of ECE, EE Building, 465 Northwestern Ave., West Lafayette, Indiana 47907-2035
Phone: 765-494-9143
Fax : 765-494-3371
Secretary: Dee Dee Dexter, 494-3558

Links: Google Scholar, 15 Rep. Papers, Press, Software Release, Awards, Talks, Ph.D. Graduates, Publications (by topic  by date  by type)


Y. Charlie Hu is an Inventor (core technologies on smartphone energy management), Entrepreneur, Open Source Contributor (released Hush - a system for reducing app background energy drain that rivals Android M app standby), Researcher (Yale, Harvard, Rice, Purdue, Microsoft Research), Educator (graduated 14 outstanding PhDs), Math Tutor (trained a MathCounts National Champ), ACM Distinguished Scientist, and IEEE Fellow.

Charlie's research interests are in Mobile, Distributed systems, Operating Systems, and Networking. He received a Honda Initiation Grant Award in 2002, the NSF CAREER Award in 2003, and the 2009 Purdue University College of Engineering Early Career Research Award. Charlie received the Ph.D. degree in Computer Science from Harvard University, was a research scientist in the Systems group at Rice University, and a visiting researcher at Microsoft Research Redmond.

Selected Publications

Energy Profiling, Debugging, and Analytics: The Foundation of AEM (App Energy Management)
A Fine-grained Event-based Modem Power Model for Enabling In-depth Modem Energy Drain Analysis (Sigmetrics 2018)
Furion: Engineering High-Quality Immersive Virtual Reality on Today's Mobile Devices (MobiCom 2017)
Wireless Network Instabilities in the Wild: Prevalence, App (non)Resilience, and OS Remedy (ICNP 2017)
GfxDoctor: A Holistic Graphics Energy Profiler for Mobile Devices (EuroSys 2017)
Unsafe Time Handling in Smartphones (USENIX ATC 2016)
Smartphone Background Activities in the Wild: Origin, Analysis and Optimization (MobiCom 2015) (read BBC and Internet-wide media coverage
Smartphone Energy Drain in the Wild: Analysis and Implications (Sigmetrics 2015) (Podcast by Scientific American)
Energy and Performance of Smartphone Radio Bundling in Outdoor Environments (WWW 2015)
On Death, Taxes, and Sleep Disorder Bugs in Smartphones (HotPower 2013)
How Much Energy Can We Save from Prefetching Ads? Energy Drain Analysis of Top 100 Apps (HotPower 2013)
Hypnos: Understanding and Treating Sleep Conflicts in Smartphones (EuroSys 2013)
Characterizing and Modeling the Impact of Wireless Signal Strength on Smartphone Battery Drain (Sigmetrics 2013) (140 cites in Google Scholar)
What is keeping my phone awake? Characterizing and Detecting No-Sleep Energy Bugs in Smartphone Apps (MobiSys 2012) (230 cites in Google Scholar)
Where is the energy spent inside my app? Fine Grained Energy Accounting on Smartphones with Eprof (EuroSys 2012, Best Student Paper Award) (570 cites in Google Scholar)
Fine-Grained Power Modeling for Smartphones Using System Call Tracing (EuroSys 2011) (320 cites in Google Scholar)
Bootstrapping Energy Debugging on Smartphones: A First Look at Energy Bugs in Mobile Devices (HotNets 2011) (180 cites in Google Scholar)

Data Center Networking:
Saath: Speeding up CoFlows by Exploiting the Spatial Dimension (CoNEXT 2017)
Cloud-scale Load Balancer - Episode III: Return of Yoda (EuroSys 2016)
Cloud-scale Load Balancer - Episode II: Unlocking the Power of Locality and End-point Flexibility in Cloud Scale Load Balancer (USENIX ATC 2015)
Cloud-scale Load Balancer - Episode I: Duet: Cloud Scale Load Balancing with Hardware and Software (SIGCOMM 2014)
On the impact of packet spraying in data center networks (INFOCOM 2013) (100 cites)
The Only Constant is Change: Incorporating Time Varying Network Reservations in Data Centers (SIGCOMM 2012) (230 cites in Google Scholar)
The TCP Outcast Problem: Exposing Unfairness in Data Center Networks (NSDI 2012)
On the Efficacy of Fine-Grained Traffic Splitting Protocols in Data Center Networks (Sigmetrics 2012 Ext. Abs.)
Latency Inflation with MPLS-based Traffic Engineering (IMC 2011)
Optimizing Cost and Performance in Online Service Provider Networks (NSDI 2010) (90 cites in Google Scholar)

Operating Systems / Buffer Cache Management:
The Performance Impact of Kernel Prefetching on Buffer Cache Replacement Algorithms (SIGMETRICS 2005, IEEE TC 2007, Software Release) (135 cites in Google Scholar)
Program Counter Based Pattern Classification in Buffer Caching (OSDI 2004) (110 cites in Google Scholar)
Program Counter Based Prediction Techniques for Dynamic Power Management (HPCA 2004, IEEE TC 2006)

Wireless Networking:
Pacifier: High-Throughput, Reliable Multicast without "Crying Babies" in Wireless Mesh Networks. (ToN 2012, Software Release) (90 cites Google Scholar)
CCACK: Efficient Network Coding Based Opportunistic Routing through Cumulative Coded Acknowledgments (ToN 2011) (160 cites Google Scholar)
Context Based Routing: Technique, Applications and Experience (NSDI 2008)
How to evaluate exotic wireless routing protocols? (HotNets 2008)
TDM MAC Protocol Design and Implementation for Wireless Mesh Networks (CoNEXT 2008)
Practical Defenses Against BGP Prefix Hijacking (CoNEXT 2007)

How to Improve Your Google Ranking: Myths and Reality (WI 2010, press: InfoExec, JH Web, SpoonyLife, 1 of 7 favorite papers of Human Factors International 2014)
Botnet Spam Campaigns can be Long Lasting: Evidence, Implications, and Analysis (SIGMETRICS 2009)
iSPY: Detecting IP Prefix Hijacking on My Own (SIGCOMM 2008, ToN 2010) (160 cites in Google Scholar)
Practical Service Provisioning for Wireless Meshes (CoNEXT 2007)
Understanding Network Delay Changes Caused by Routing Events (SIGMETRICS 2007)
On the Impact of Research Network Based Testbeds on Wide-area Experiments (IMC 2006)

Exploiting the Synergy between Peer-to-Peer and Mobile Ad Hoc Networks (HotOS 2003) (140 cites in Google Scholar)
Runtime Support for Distributed Sharing in Safe Languages (ACM TOCS 2003)



Recent Projects:

Software Releases


Research in our group has been supported by

Ph.D Students

Note to applicants

Past Postdoc

Ph.D. and M.S. Graduates (17 + 3)


ECE 469 Operating Systems Engineering (Spring 2015, 2014, 2013, 2011-2009, 2007-2005, 2003, 2002)
ECE 673 Distributed Computing Systems (Fall 2014, 2012, 2011, 2010, 2007-2002)
ECE Wireless Networking Seminar (Spring 2011)
ECE Wireless Networking Seminar (Fall 2010)

Professional activities


             o o O O O O O O O
            o    _______
            Y__'_|_|_|_| --++++++--
           |__|__| GO ||| BOILERS! |
           //oo-----oo      oo---oo