Timeline for Are all MMA computations single-core unless explicitly parallelized?
Current License: CC BY-SA 4.0
8 events
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| Dec 22, 2021 at 15:48 | comment | added | Szabolcs | These options simply control how many parallel computation threads will be running. How those threads are distributed among available hardware resources is up to the operating system, and is not controlled by Mathematica. | |
| Dec 22, 2021 at 6:00 | history | tweeted | twitter.com/StackMma/status/1473533785664806913 | ||
| Dec 22, 2021 at 5:10 | comment | added | theorist |
@MarcoB Question: I assume when I'm selecting both the ParallelThreadNumber -> 1 and MKLThreadNumber -> 1 options, what those actually mean are "run on 1 core", not "run with 1 thread", right? Because if those options really are referring to the number of threads then, e.g., ParallelThreadNumber -> 2 would mean: "Run on 1 core, with Hyperthreading enabled" and ParallelThreadNumber -> 1 would mean "Run on 1 core, with Hyperthreading disabled". And I don't think that's how those work—particularly since the default configuration with my 4-kernel license is ParallelThreadNumber -> 4.
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| Dec 22, 2021 at 5:10 | comment | added | theorist | @MarcoB Thanks, I missed those in my own search. I tried running Benchmark with MKLThreadNumber reduced from 4->1, ParallelThreadNumber reduced from 4->1, and both reduced from 4->1. Averaging two runs, 10 Benchmarks/run, for each configuration (i.e., 20 Benchmarks/config total), I got score reductions (in quadrature) of 14%, 15%, and 24%, respectively, indicating (a) Benchmark uses multiple cores for both MKL and non-MKL operations; and (b) MMA can run MKL with multiple cores even when ParallelThreadNumber is set to 1. | |
| Dec 22, 2021 at 3:16 | comment | added | MarcoB | To answer the question in your title: Mathematica will automatically run some functions in parallel on its own if the resources are available. See for instance this question discussing how to prevent that: How to force an evaluation to use only one core; and Are built-in Mathematica functions already parallelized?. | |
| Dec 22, 2021 at 2:55 | history | edited | theorist | CC BY-SA 4.0 |
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| Dec 22, 2021 at 2:49 | history | edited | theorist | CC BY-SA 4.0 |
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| Dec 22, 2021 at 2:43 | history | asked | theorist | CC BY-SA 4.0 |