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There was a false dependency on readReg2 and readReg3 (caused by `xor rbp, rax` instruction) when reading dataset item (see design.md - 4.6.2 Loop execution, steps 5 and 7). This change uses `ma` register to read dataset item before the whole `rbp` (`ma` and `mx`) is changed, so superscalar and out-of-order CPU can start executing it earlier. Results: https://i.imgur.com/Bpeq9mx.png ~1% speedup on modern Intel/AMD CPUs.
Break dependency from readReg2 and readReg3.
Owner
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I can confirm a 0.6% speedup on Ryzen 3700X. |
Owner
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However, if you run |
Collaborator
Author
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This is weird. I got a correct hash after 100k iterations, see screenshot. What's in test 84? |
Collaborator
Author
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I've just double checked that randomx-benchmark.exe gives correct hashes. I'll look into it. |
Owner
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Everything works now. |
malbit
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Dec 1, 2021
* Optimized dataset read There was a false dependency on readReg2 and readReg3 (caused by `xor rbp, rax` instruction) when reading dataset item (see design.md - 4.6.2 Loop execution, steps 5 and 7). This change uses `ma` register to read dataset item before the whole `rbp` (`ma` and `mx`) is changed, so superscalar and out-of-order CPU can start executing it earlier. Results: https://i.imgur.com/Bpeq9mx.png ~1% speedup on modern Intel/AMD CPUs. * ARMv8: optimized dataset read Break dependency from readReg2 and readReg3. * Fixed light mode hashing
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There was a false dependency on readReg2 and readReg3 (caused by
xor rbp, raxinstruction) when reading dataset item (see design.md - 4.6.2 Loop execution, steps 5 and 7). This change usesmaregister to read dataset item before the wholerbp(maandmx) is changed, so superscalar and out-of-order CPU can start executing it earlier.Results: https://i.imgur.com/Bpeq9mx.png
~1% speedup on modern Intel/AMD CPUs.