[Dev-luatex] LuaJIT?

Hans Hagen pragma at wxs.nl
Tue Mar 31 19:00:15 CEST 2009


Mohamed Bana wrote:
> Hi guys,
> 
> has anyone luatex working with luajit?  so far i've only managed to get 
> to compile a 32bit version under ubuntu 64 bit - /luajit hasn't been 
> ported to a 64 bit yet/.
> 
> Currently the interpreter works.
> 
> here's the difference in speed between standard lua and the jit 
> version;  
> http://shootout.alioth.debian.org/u32q/benchmark.php?test=all&lang=all&box=1, 
> and generally; http://shootout.alioth.debian.org/.
> 
> In summary; I'd just like to know how much roughly how much effort is 
> required and If anyone has looked into it.

i played with it when we started with luatex (luajit < 2)

my concusion at that time was that it does not really speeds up luatex 
unless you use it for number crunching; at the moment i played with it i 
had to tweak the jit (runtime) parameters )

of course luajit is impressive but i'm not sure if it pays off for the 
kind if tasks luatex does - node list processing to mention one - unless 
for instance it turns user data function calls into inline code

also code that only is used once in a run does not profit much

talking of speed, a rather sensitive area is garbage collection; tuning 
the parameters turned out not to help speed up luatex

yet another factor is the binary itself ... for instance, where luatex 
0.36 takes 52 sec for our test document, version 0.37 takes 44 seconds 
(on my machine)

of course i might be wrong

Hans

ps. at that time we decided not to spend too much time on it as it is 
only available for some architectures and it adds complexity so it went 
on the > 1.0 agenda


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