JTE : mémoires partagées réparties

Run-time Support for Distributed Sharing in Strongly Typed Languages
Willy ZWAENEPOEL Department of Computer Science, Rice University
Joint work with Alan L. Cox, Y. Charlie Hu, and W. Yu.

Abstract: Traditional DSM systems target either coarse-grain sharing by using the virtual memory system, or fine-grain sharing by instrumenting reads and writes. We demonstrate that, by taking advantage of type information, it is possible to build a DSM that supports both granularities with good performance. The new system also has substantial advantages for programs using garbage collection, a common feature in modern programming languages.

The key insight is that strong type information allows the use of a handle table, through which all object references are indirected. While still preserving the abstraction of a globally shared space, this indirection allows objects to be allocated at different virtual memory locations on different machines. This, in turn, can be used to reduce false sharing and memory footprint. Additional optimizations are necessary to make the system competitive with conventional coarse- grain and fine-grain DSMs, including read and write aggregation, and lifting indirections out of loop nests.

Comparing the new system to TreadMarks, performance is comparable for fine-grain applications, but substantially better for fine-grain and garbage-collected applications.