Re: Installing luaJIT : no performance gain !

[Sylvain Fabre <sylvain.fabre@...>]

Thanks for you hints, Mike !
I finally found that the core reason is that we are using our internal 
IDE to launch scripts during the development phase, and the IDE is using 
the lua_debug interface, by settings some hooks.
When the script is called without this, it works perfectly !

Thanks, Sylvain.

Le 25/01/2011 16:16, Mike Pall a écrit :
> Sylvain Fabre wrote:
> > After a few tests with some scripts, i have strictly no performance
> > gain between both versions. Even worse : in some cases, luaJIT is
> > slower than lua51.
> How much of the CPU time of your application is spent in Lua code?
> How much of the CPU time is spent in C/Lua and Lua/C transitions?
> If you cannot readily answer these questions then I suggest to
> profile your application first.
>
> > I am sure to use the right LUA DLL, as the "jit" object exists when
> > i link with luaJIT.
> Umm, which version do you use?
>
> > I guess that i forgot something at the installation or run level. Any idea ?
> Have you followed the instructions in
>    http://luajit.org/install.html#embed
> ?
>
> > Or do you have a typical bench script, in order for me to be sure
> > that i can reproduce the same environnement than in the benchmark
> > page of luaJIT ?
> Here's a trivial test:
>
>    local x=0; for i=1,1e9 do x=math.abs(x) end
>
> This should run in a fraction of a second with LuaJIT 2.0, but
> will take more than a minute with Lua. It's around 214x faster.
>
> --Mike


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Sylvain FABRE
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