CAS-DSM: A Compiler Assisted Software Distributed Shared Memory

Traditional software Distributed Shared Memory (DSM) systems rely on the virtual memory management mechanisms to detect accesses to shared memory locations and maintain their consistency. The resulting involvement of the OS (kernel) and the associated overhead which is significant, can be avoided by careful compile time analysis and code instrumentation. In this paper, we propose such a Compiler Assisted Software support approach (CAS-DSM). In the CAS-DSM implementation, the involvement of the OS kernel is avoided by instrumenting the application code at the source level. The overhead caused by the execution of the instrumented code is reduced through several aggressive compile time optimizations. Finally, we also address the issue of reducing certain overheads in polling-based implementation of receiving asynchronous messages. We used SUIF, a public domain compiler tool, to implement compile time analysis, instrumentation and optimizations. We modified CVM, a publicly available software DSM to support the instrumentation inserted by the compiler. Detailed performance evaluation of CAS-DSM is reported using a set of Splash/Splash2 parallel application benchmarks on a distributed memory IBM SP-2 machine. CAS-DSM achieved moderate to good performance improvements for most of the applications compared to the original CVM implementation. Reducing the overheads in polling-based implementation improves the performance of CAS-DSM significantly resulting in an overall improvement of 12–52% over the original CVM implementation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44573/1/10766_2004_Article_482234.pd

Responsiveness without Interrupts

this paper is a characterization of the delays actually observed in a suite of applications. We show that the majority of notification delays result from a small number of large delays. These delays can dominate any gains achieved through use of new network technologies. The impact of these delays can be considerable. Our applications averaged more than 31% slower without interrupts than with them. This result argues that the problem is serious, and needs to be addressed either by including interrupts in emerging standards, or through use of the techniques discussed belo