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Re: Patch to make string-append on win32 100 times faster

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Nicholas Clark
July 31, 2010 08:04
Re: Patch to make string-append on win32 100 times faster
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On Fri, Jul 30, 2010 at 11:26:15PM +0200, wrote:
> From: Marvin Humphrey <>
> Date: 30.07.2010 17:34
> >>* Why the "+10"?  Why have a extra minimum at all?  Why "10" instead
> >>of another number?  Given your examples, for a large string the 10 is
> >>a trivial fraction of the total and for a small string, the efficiency
> >>either doesn't matter or the string quickly grows into a large string
> >>anyway.
> >>    
> >
> >That's similar to my analysis.  I think it's more useful to round up to a
> >multiple of the pointer size for small values.
> >  
> If I understand correctly (which I'm not certain about), this is done 
> anyway right afterwards in
> newlen = PERL_STRLEN_ROUNDUP(newlen);

That's certainly what the expression in PERL_STRLEN_ROUNDUP() is intended to
do. (Round up to a multiple of the pointer size, so that growth of strings by
small amounts usually avoids repeated realloc() calls for an extra 1 or 2

I'm not sure what my opinion on the main proposal is.
(I don't have time to read and digest all my mail currently)

Nicholas Clark

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