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Check to limit nr of threads for small problems #387
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swernli
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Sep 28, 2020
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swernli
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Changes seem good to me. Have we verified that these boundaries don't make the perf of small problems on Windows too much worse than it was before the original improvements get checked in?
rmshaffer
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Sep 28, 2020
| if (nMaxThrds > 4) nMaxThrds/= 2; // Assume we have hyperthreading (no consistent/concise way to do this) | ||
| if (wfnCapacity < 1u << 20) { | ||
| if (wfnCapacity < 1ul << 14) nMaxThrds = 1; | ||
| else if (wfnCapacity < 1ul << 16) nMaxThrds = 2; |
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Minor note: looks like this line would actually increase nMaxThrds from 1 to 2 if running on a single-core CPU? Is that the intent?
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No, but I haven't seen a 1 CPU machine in a long time. Easy to add the check if desired.
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Up to you. As you say, this is probably a rare case in practice.
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