Most current compiler analysis techniques are unable to cope with the semantics introduced by explicit parallel and synchronization constructs in parallel programs. In this paper we propose new analysis and optimization techniques for compiling explicitly parallel programs that use mutual exclusion synchronization. We introduce the CSSAME form, an extension of the Concurrent Static Single Assignment (CSSA) form that incorporates mutual exclusion into a data flow framework for explicitly parallel programs. We show how this analysis can improve the effectiveness of constant propagation in a parallel program. We also modify a dead-code elimination algorithm to work on explicitly parallel programs. Finally, we introduce lock independent code motion, a new optimization technique that attempts to minimize the size of critical sections in the program.

We present a new facility for cross-address space IPC that exploits queues in memory shared between the client and server address space. The facility employs only widely available operating system mechanisms, and is hence easily portable to different commercial operating systems. It incorporates blocking semantics to avoid wasting processor cycles, and still achieves almost twice the throughput of the native kernel-mediated IPC facilities on SGI and IBM uniprocessors. In addition, we demonstrate significantly higher performance gains on an SGI multiprocessor. We argue that co-operating tasks will be better served if the operating system is aware of the co-operation, and propose an interface for a hand-off-scheduling mechanism. Finally, we report initial performance results from a Linux implementation of our proposal.

A reader-writer (RW) lock allows either multiple readers to inspect shared data or a single writer exclusive access for modifying that data. On shared memory multiprocessors,cost of acquiring and releasing these locks can have a large impact on the performance of parallel applications. A major problem with naive implementations of these locks, where processors spin on a global lock variable waiting for the lock to become available, is that the memory containing the lock and the interconnection network to that memory will also become contended when the lock is contended.