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- Subject: Re: Lua 5.0 to 5.1 performance regression?
- From: Glenn Maynard <glenn@...>
- Date: Sun, 24 Sep 2006 21:53:03 -0400
On Sun, Sep 24, 2006 at 08:26:51PM -0500, Rici Lake wrote:
> On 24-Sep-06, at 7:33 PM, Glenn Maynard wrote:
> > iFreeListRef = ref;
> > if(ref == iMaxReference)
> > --iMaxReference;
> I think that should be:
> if (ref == iMaxReference)
> iFreeListRef = ref;
> Otherwise, you'll give out the same references twice.
The logic is the same as in lauxlib; it's just forming a linked list
of indexes, where iFreeListRef is the head.
> You may find it faster to nil out the reference table entry, and keep
> the free list in your own private datastructure; it's possible that
> your compiler is not generating good code for converting between
I tried that, to reduce table accesses a bit more; the difference was
measurable but not very much.
> integer and floating point. (In general, you should use lua_pushinteger
I just changed it to pushnumber for comparing 5.0 and 5.1; I didn't
see any difference. (I think that, since Lua currently stores only
floats internally, it has to do the conversion either way.)
> with lua 5.1, I think.) You could also try storing the freelist indices
> coerced to (void *) and wrapped as lightuserdata.
I tried a different approach with the same effect: storing the indexes
in a C++ vector, which gave maybe a 10% improvement, but still not bringing
it close to 5.0's speed, and also giving 5.0 a comparable speedup.