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- Subject: Re: [ANN] Lua 5.4.0 (work2) now available
- From: Roberto Ierusalimschy <roberto@...>
- Date: Thu, 23 Aug 2018 14:04:21 -0300
> I've tested the performance of one program under Lua 5.1 / 5.2 / 5.3 / 5.4
> The program is just a calculator of SHA512 written for Lua 5.1, all bitwise
> operations are emulated with arithmetic.
> The code is here: https://stackoverflow.com/a/51561685/6834680
> (the code consists of two files: the module and the testing/benchmarking
> All Lua executables under test are 64-bit, built with the same script under
> the same compiler.
> So, the benchmarking is fair.
> C:\>lua51.exe sha2for51_test.lua
> CPU seconds: 12.371
> C:\>lua52.exe sha2for51_test.lua
> CPU seconds: 12.513
> C:\>lua53.exe sha2for51_test.lua
> CPU seconds: 16.801
> C:\>lua54.exe sha2for51_test.lua
> CPU seconds: 15.6
At least in my machine, this time difference mainly boils down to
the mod operation. If I compile lua 5.4 using the old (but slightly
wrong) definition for '%', Lua 5.4 runs 4% slower than Lua 5.1, which
I think is due to the high number of coercions between integers and
We can try to improve the implementation of '%' for floats, but
I am not sure it is worth, given that, with integers and bitwise
operations, that kind of use of '%' for floats is much diminished.