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Section: Software

Keywords : Cache Optimizations, Event-driven Programs, Domain-specific optimizations.

Stingy - A Domain-Specific Compiler for High-performance Network Servers

Participants : Sapan Bhatia [ correspondent ] , Charles Consel, Julia Lawall.

Event-driven programming has emerged as a standard to implement high-performance servers due to its flexibility and low OS overhead. Still, memory access remains a bottleneck. Generic optimization techniques yield only small improvements in the memory access behavior of event-driven servers, as such techniques do not exploit their specific structure and behavior.

The Stingy compiler implementes an optimization framework dedicated to event-driven servers, based on a strategy to eliminate data-cache misses. Our approach exploits the flexible scheduling and deterministic execution of event-driven servers. It is based on a novel memory manager combined with a tailored scheduling strategy to restrict the working data set of the program to a memory region mapped directly into the data cache.

In practice, the Stingy compiler accepts as input an event-driven server written in C and annotated to expose a specific memory management and scheduling interface. As output, it generates C code for an optimized version of the server. The Stingy compiler has been tested on the following servers: The TUX, thttpd, Flash, boa, mathopd. It has also been applied to the Cactus QoS framework and the Squid proxy server. The highest speedup observed under heavy loads is on the TUX server (in the range of 40%). For the remaining servers, gains are in the region of 10-15%.


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