Re: [ANN] Lua 5.2.1 (work1) now available

[KHMan <keinhong@...>]

On 3/25/2012 9:49 AM, David Manura wrote:
> On Thu, Mar 22, 2012 at 2:43 PM, KHMan wrote:
> > (a) load data, parse, dump into two arrays [...]
> > lua-5.2.0       0.261   0.274   0.285
> > lua-5.2.1wk1
> >   shortlen=16    0.180   0.188   0.204
> >   shortlen=32 0.224 0.201   0.220
> No difference in word count (wc): http://www.lua.org/pil/21.2.1.html .
> [snip]
Yeah, I don't think there will be a lot of difference for most 
workloads. I am also curious on how well the random hash seed is 
working compared to 5.2.0.
The samples I posted are extreme examples that use strings mostly 
of a particular type (crypto hash hex keys and relative paths) and 
the large differences in short/long string usage are amplified 
through reps. Mainly, I wanted to get a feel of the tradeoffs... 
though I rather like shortlen=64.
Would be nice to see actual apps that use extreme levels of long 
string lookups or longstr==longstr compares, but they may be a 
rarity. On the other hand, for long-running apps, slightly faster 
loading of text due to less string interning does not matter that 
much.
Intern on first compare is not easy to implement, there are a lot 
of complications. A quick-and-dirty attempt at using long string 
hash values to avoid extra memcmp() work didn't really work (a few 
% slower than default lua-5.2.1wk1) because in the examples I am 
using, there are a lot of equal compares (76%) which means 
memcmp() is still mostly needed. Short string compares is still 
much faster.
--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia