Re: LuaJIT Lua Gulf? (Was: Why I leave Lua..)

[Eric Wing <ewmailing@...>]

>>
>
> I am not expert in this but I also did some crude benchmark back then. If
> you are benchmarking using a program that actually draws sprites, then I
> think the bottleneck isn't even the Lua/C API barrier, as it should be
> actually drawing things on the screen, no? Or that's already been accounted
> for?

This is a very fair question. I claim I did account for it, to a
degree. I ran on different video card video hardware and operating
systems (drivers) to get a sense of which ones I'm testing on are GPU
bound vs. CPU bound. So I won't claim that that the 60% and 75% speed
of the C control is always true. However, the relationship between Lua
and LuaJIT did hold up.

> And I think there's no bad information, but there might be people who jump
> to conclusion too easily and think LuaJIT can boost their program at least
> 2~3 times faster no matter what they write down in Lua.
>
> Information can simply be obtained by looking at:
> http://luajit.org/performance_x86.html
> http://luajit.org/performance_arm.html
>
> As you can see if you switch to Lua v.s. LuaJIT2 interpreter-only
> benchmark, on x86/64 it's ranging from 1.5x ~ 5.5x, so you would consider
> generally a 2 ~ 3 times speedup can be expected, if it's pure Lua. However,
> on ARM it's only 1x ~ 3.5x ... So, if the same experiment on PC already
> yield only a little improvement, on non-jitted ARM environments the speedup
> can be nearly non-existent.

Thank you. This gets more into the specific information I'm interested
in. It's good to see the constraints for once.

Thanks,
Eric
-- 
Beginning iPhone Games Development
http://playcontrol.net/iphonegamebook/