[luatex] slower texlua at LuaTeX 1.0.4 (TL 2017) ?

[Mojca Miklavec]

On 2 June 2017 at 15:07, jfbu wrote:
> Hi Herb,
>
> Le 02/06/2017 à 14:51, Herbert Schulz a écrit :
>>> On Jun 2, 2017, at 5:10 AM, jfbu wrote:
>>>
>>> $ time texlua collatz.lua 1 1000000
>>> 837799
>>>
>>> real 0m39.053s
>>> user 0m39.034s
>>> sys  0m0.017s
>>>
>>
>> Howdy,
>>
>> I'm getting
>>
>> $ time texlua collatz.lua 1 1000000
>> 837799
>>
>> real  0m17.333s
>> user  0m17.119s
>> sys   0m0.014s
>>
>> using the x86_64-darwin (for macOS 10.10 and later) and TL 2017 (almost not pretest?).
>
> ah! thanks! so there is possibly a problem indeed with x86_64-darwinlegacy

The x86_64-darwinlegacy binaries were compiled with gcc 4.2 on 10.6
and most likely without any substantial audience of testers.

The x86_64-darwin binaries were compiled with clang on 10.10.

We had a similar issue with i386-linux binaries being roughly 100%
slower only due to some optimisation flags, it might be possible that
changing some compiler flags or switching to a more modern compiler
would help.

It would be interesting to compare time of execution of your script on
the same machine using:
- 2016/x86_64-darwin
- 2017/x86_64-darwin
- 2017/x86_64-darwinlegacy
- 2017 luatex that you compile yourself
and then perhaps some or all of these once again with texluajit.

If only 2017/x86_64-darwinlegacy is 2 times slower, I'm sure we'll
find a cure, any help or testing appreciated. It's no problem to
replace the binaries (after TL 17 release) with faster ones if we
figure out what exactly to do.

> I expect other mac os users will be with x86_64-darwinlegacy.
> A possibly 100% slow-down of luatex is perhaps not a big deal
> if it happens only in directlua code.

It should not be a dealbreaker in any case. (It's just a small price
to pay for not upgrading your OS :)

Mojca