Re: Lua is faster than Java?

[Tim Gogolin <tgogolin@...>]

Yes, I realize that making performance claims without mentioning  
system details is not particularly useful. For the record, that 5%  
improvement came on a Dual 2Ghz G5, running an optimized (gcc 4)  
build of the lua engine.  But regardless of platform specifics, I  
wasn't expecting that much of an improvement after only 30 seconds of  
playing with the code :-)

-- Tim Gogolin
   Adobe Systems

On Jul 25, 2005, at 3:23 PM, Tim Gogolin wrote:

> Interesting. Out of curiosity, I went to the shootout website and  
> picked a random benchmark (n-body), and looked for trivial  
> optimizations that hadn't been made...
>
> Replacing
>            x = math.sqrt( y )
> with
>            x = math_sqrt( y ) -- make math_sqrt a local that is  
> defined above the inner loop code
>
> saves several thousand table lookups and chops 5% off the runtime.  
> So apparently there really are trivial changes we could do to  
> improve lua's performance in these benchmarks... Is this enough of  
> a well known resource that it would be worth improving lua's  
> performance for? (Apologies if that is a silly question)
>
> -- Tim Gogolin
> Adobe Systems
>
>
>
> > > Yes, there is.
> > >
> > > 1. Some of the Lua benchmarks there are not optimized.
> > > I've hand-optimized a few of them (with sizeable gains), but
> > > I've not had the time to clean them up and submit them, yet.
> > >
> > > 2. They've added quite a few new benchmarks recently and not
> > > all of them have Lua equivalents, yet. This has a very negative
> > > impact on the ranking, too.
> > >
> > > 3. Another problem is that they are using a Lua binary that has
> > > the Lua core compiled as a shared library. Unfortunately this
> > > comes with a sizeable performance loss on x86 CPUs. Since the
> > > other languages are statically compiled, the comparison is
> > > not completely fair.
> > >
> > > Note: Yes, all of this is our (the Lua community's) fault.
> > > The shootout maintainers just take whatever the respective
> > > language community gives them. IMHO we should do something
> > > about it. It's not good for Lua PR.
> > >
> > > Could someone else please step up and take the lead for
> > > fixing #1 and #2? I will gladly send my optimized versions
> > > to anyone's mailbox. I have: ackermann, count-words, random,
> > > spellcheck, tcp-echo, threads, threads-flow, word-frequency.
> > > [All the others I optimized have been removed from the shootout.]
> > >
> > > We already discussed #3 in March/April with no immediate
> > > solution.
> > >
> > > Bye,
> > >      Mike