Cilk (pronounced "silk") is a C-based runtime system for multithreaded parallel programming. In this paper, we document the efficiency of the Cilk work-stealing scheduler, both empirically and analytically. We show that on real and synthetic applications, the "work" and "critical-path length" of a Cilk computation can be used to model performance accurately. Consequently, a Cilk programmer can focus on reducing the computation' s work and critical-path length, insulated from load balancing and other runtime scheduling issues. We also prove that for the class of "fully strict" (well-structured) programs, the Cilk scheduler achieves space, time, and communication bounds all within a constant factor of optimal.The Cilk runtime system currently runs on the Connection Machine CM5 MPP, the Intel Paragon MPP, the Sun Sparcstation SMP, and the Cilk-NOW network of workstations. Applications written in Cilk include protein folding, graphic rendering, backtrack search, and the ?Socrates chess program, which won second prize in the 1995 World Computer Chess Championship.

In this paper, we analyze the performance of parallel multithreaded algorithms that use dag-consistent distributed shared memory. Specifically, we analyze execution time, page faults, and space requirements for multithreaded algorithms executed by a workstealing thread scheduler and the BACKER algorithm for maintaining dag consistency. We prove that if the accesses to the backing store are random and independent (the BACKER algorithm actually uses hashing), the expected execution time T P (C) of a "fully strict" multithreaded computation on P processors, each with a LRU cache of C pages, is O(T 1 (C)=P + mCT ∞ ), where T 1 (C) is the total work of the computation including page faults, T ∞ is its critical-path length excluding page faults, and m is the minimum page transfer time. As a corollary to this theorem, we show that the expected number F P (C) of page faults incurred by a computation executed on P processors can be related to the number F 1 (C) of serial page faults by the formula F P (C) F 1 (C) + O(CPT ∞ ). Finally, we give simple bounds on the number of page faults and the space requirements for "regular" divide-and-conquer algorithms. We use these bounds to analyze parallel multithreaded algorithms for matrix multiplication and LU-decomposition.

Abstract

Cilk (pronounced "silk") is a C-based runtime system for multithreaded parallel programming.In this paper, we document the efficiency of the Cilk work-stealing scheduler, both empirically and analytically. We show that on real and synthetic applications, the "work" and "critical path" of a Cilk computation can be used to accurately model performance. Consequently, a Cilk programmer can focus on reducing the work and critical path of his computation, insulated from load balancing and other rtmtime scheduling issues. We also prove that for the class of "fully strict" (well-structured) programs, the Cilk scheduler achieves space, time, and communication bounds all within a constant factor of optimal. The Cilk rmrtime system currently runs on the Connection Machine CM5 MPP, the Intel Paragon MPP, the Silicon Graphics Power Challenge SMP, and the MIT Phish network of workstations.Applications written in Cilk include protein folding, graphic rendering, backtrack search, and the *Socrates chess program, which won third prize in the

Cilk (pronounced "silk") is a C-based runtime system for multithreaded parallel programming.In this paper, we document the efficiency of the Cilk work-stealing scheduler, both empirically and analytically. We show that on real and synthetic applications, the "work" and "critical path" of a Cilk computation can be used to accurately model performance. Consequently, a Cilk programmer can focus on reducing the work and critical path of his computation, insulated from load balancing and other rtmtime scheduling issues. We also prove that for the class of "fully strict" (well-structured) programs, the Cilk scheduler achieves space, time, and communication bounds all within a constant factor of optimal. The Cilk rmrtime system currently runs on the Connection Machine CM5 MPP, the Intel Paragon MPP, the Silicon Graphics Power Challenge SMP, and the MIT Phish network of workstations.Applications written in Cilk include protein folding, graphic rendering, backtrack search, and the *Socrates chess program, which won third prize in the

No abstract

No abstract

No abstract