Re: Drawing the line between speed and simplicity/elegance

Subject: Re: Drawing the line between speed and simplicity/elegance
From: Brigham Toskin &lt;brighamtoskin@ ... &gt;
Date: Sat, 9 May 2015 17:31:43 -0700

On Sat, May 9, 2015 at 4:47 PM, Eric Wing <ewmailing@gmail.com> wrote:

On 5/9/15, Rena <hyperhacker@gmail.com> wrote:
> On Sat, May 9, 2015 at 1:01 PM, Roberto Ierusalimschy
> <roberto@inf.puc-rio.br> wrote:
>>> Using the C API will make LuaJIT's performance bottom out. If you're
>>> worried about performance across VMs, stick to pure Lua.
>>
>> That is not a valid advice across VMs. C code is much faster than
>> (non-JIT) Lua code. So, not using the C API will hurt Lua performance.
>>
>> -- Roberto
>>
>
> But Lua also has some overhead with calling into C, doesn't it? So
> some common operations are faster in pure Lua than in C? I'm sure I've
> heard that.
>

I did some microbenchmarks like 2 years ago on this which I think I
mentioned on the list. If I recall my experiments correctly, I was
surprised that this was not the case and the calling overhead of
calling C implemented functions from Lua was faster than calling Lua
functions.

That's interesting to hear. Like everything, the details of the code involved probably make a difference. I'm also wondering, (a) whether this was PUC-Rio Lua or LuaJIT (or both)?, and (b) were you just measuring call overhead, or taking into account implementing equivalent calculations?

Brigham Toskin