Workshop on Hot Topics in Operating Systems 

About: Workshop on Hot Topics in Operating Systems is an academic conference. The conference publishes majorly in the area(s): Scalability & The Internet. Over the lifetime, 146 publications have been published by the conference receiving 6751 citations.

When virtual is harder than real: security challenges in virtual machine based computing environments

Abstract: As virtual machines become pervasive users will be able to create, modify and distribute new "machines" with unprecedented ease. This flexibility provides tremendous benefits for users. Unfortunately, it can also undermine many assumptions that today's relatively static security architectures rely on about the number of hosts in a system, their mobility, connectivity, patch cycle, etc. We examine a variety of security problems virtual computing environments give rise to. We then discuss potential directions for changing security architectures to adapt to these demands.

Scalability! but at what cost?

Abstract: We offer a new metric for big data platforms, COST, or the Configuration that Outperforms a Single Thread The COST of a given platform for a given problem is the hardware configuration required before the platform outperforms a competent single-threaded implementation COST weighs a system's scalability against the overheads introduced by the system, and indicates the actual performance gains of the system, without rewarding systems that bring substantial but parallelizable overheads We survey measurements of data-parallel systems recently reported in SOSP and OSDI, and find that many systems have either a surprisingly large COST, often hundreds of cores, or simply underperform one thread for all of their reported configurations

Why events are a bad idea (for high-concurrency servers)

Abstract: Event-based programming has been highly touted in recent years as the best way to write highly concurrent applications Having worked on several of these systems, we now believe this approach to be a mistake Specifically, we believe that threads can achieve all of the strengths of events, including support for high concurrency, low overhead, and a simple concurrency model Moreover, we argue that threads allow a simpler and more natural programming style We examine the claimed strengths of events over threads and show that the weaknesses of threads are artifacts of specific threading implementations and not inherent to the threading paradigm As evidence, we present a user-level thread package that scales to 100,000 threads and achieves excellent performance in a web server We also refine the duality argument of Lauer and Needham, which implies that good implementations of thread systems and event systems will have similar performance Finally, we argue that compiler support for thread systems is a fruitful area for future research It is a mistake to attempt high concurrency without help from the compiler, and we discuss several enhancements that are enabled by relatively simple compiler changes

High availability, scalable storage, dynamic peer networks: pick two

Abstract: Peer-to-peer storage aims to build large-scale, reliable and available storage from many small-scale unreliable, low-availability distributed hosts. Data redundancy is the key to any data guarantees. However, preserving redundancy in the face of highly dynamic membership is costly. We use a simple resource usage model to measured behavior from the Gnutella file-sharing network to argue that large-scale cooperative storage is limited by likely dynamics and cross-system bandwidth -- not by local disk space. We examine some bandwidth optimization strategies like delayed response to failures, admission control, and load-shifting and find that they do not alter the basic problem. We conclude that when redundancy, data scale, and dynamics are all high, the needed cross-system bandwidth is unreasonable.

TCP offload is a dumb idea whose time has come

Abstract: Network interface implementors have repeatedly attempted to offload TCP processing from the host CPU These efforts met with little success, because they were based on faulty premises TCP offload per se is neither of much overall benefit nor free from significant costs and risks But TCP offload in the service of very specific goals might actually be useful In the context of the replacement of storage-specific interconnect via commoditized network hardware, TCP offload (and more generally, offloading the transport protocol) appropriately solves an important problem