![]() Moreover, even if overheads were several times greater, applications using DotMix should be amply fast for debugging purposes, which is a major reason for desiring repeatability. For a naive Fibonacci calculation with n=40 that calls DotMix in every node of the computation, this "price of determinism" is a factor of 2.65 in running time, but for more realistic applications with less intense use of random numbers - such as a maximal-independent-set algorithm, a practical samplesort program, and a Monte Carlo discrete-hedging application from QuantLib - the observed "price" was less than 5%. The cost of calling DotMix depends on the "spawn depth" of the invocation. The statistical quality of DotMix is comparable to that of the popular Mersenne twister, but somewhat slower than a nondeterministic parallel version of this efficient and high-quality serial random-number generator. ![]() We persuaded Intel to modify its commercial C/C++ compiler, which provides the Cilk Plus concurrency platform, to include pedigrees, and we built a library implementation of a deterministic parallel random-number generator called DotMix that compresses the pedigree and then "RC6-mixes" the result. Specifically, on a suite of 10 benchmarks, the relative overhead of Cilk with pedigrees to the original Cilk has a geometric mean of less than 1%. Experiments with the open-source MIT Cilk runtime system show that the overhead for maintaining pedigrees is negligible. ![]() Dont settle for a random phone number from your service provider. ![]() new or modified algorithm for generating random numbers. This paper proposes that a mechanism called pedigrees be built into the runtime system to enable efficient deterministic parallel random-number generation. Get local phone numbers for cities and towns like New York, NY. Random(Int32) constructor, or implicitly by calling the Random() constructor. Existing concurrency platforms for dynamic multithreading do not provide repeatable parallel random-number generators. ![]()
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