Hot Topics in OS Research Andy Wang COP 5611 Advanced Operating Systems

Some Hot Areas Safely executing untrusted code File and storage systems Ubiquitous computing Virtual machine environments Reliability

Safely Executing Untrusted Code Type-safe languages Virtual machines Verified code

File and Storage Systems Very large-scale file systems  Reliability  Performance vs. cost of ownership  Energy consumption Very long-term storage Peer-to-peer backup system  Challenges: privacy, consistency over encrypted data, fairness

File and Storage Systems Some advanced tools:  Rabin fingerprinting  Compare-by-hash  Convergent encryption  Erasure code  Bloom filter  Search on encrypted domain

Ubiquitous Computing Lots and lots of inexpensive mobile wireless devices Distributed resource sharing across untrusted domains  Economic models Bartering Tickets Credits

Ubiquitous Computing Distributed resource discovery  Pastry, Tapestry, Chord Hypercube routing Distributed radix sort O(log(n))  O(1) lookup with clever replication Distributed access control models Peer-to-peer coordination

Ubiquitous Computing Constrained resources  CPU Cannot afford strong security measures  Memory, disk  Variable bandwidth  Energy Battery density approaches that of a grenade Sensor networks

Ubiquitous Computing E-commerce  How to authenticate with unknown servers?  How to make e-cash anonymous, transferable, non-traceable, and non- forgeable?  How to prevent free-rides?  How to provide micropayments?

Virtual Machine Environments OS support for efficient executions  Parasitic virtualization

Reliability Running device drivers in isolated kernel address spaces Static code analysis for common programming errors Soft-state-only systems, designed to crash

Reliability Use computational dependencies to locate failures Secure hardware to certify software General security

Revisiting Existing Designs Path  Vertical paths vs. layers Capriccio  Event-based scheduling  Threads with linked stacks to conserve storage Conquest  Lots of RAM

Introspective Computing Self-administration  Configuration, optimization, evolution  Exploit contextual information Autonomous computing  Automatically detect and repair system problems

Performance Rewrite binaries for smaller memory footprint Use compiler to cluster and issue bulk system calls Download user-level binaries into the kernel