Re: [ANN] Lua 5.2.1 (rc3) now available

[Roberto Ierusalimschy <roberto@...>]

> Hmm, on my test case, rc3 seems to consistently increase runtime by
> about 10% compared to rc1.  [I didn't test rc2, so maybe the changes
> there are the reason.]
> 
> A bit mystifying as rc1 was noticeably faster even when matching rc3's
> memory usage...

I think the collector in rc3 is a bit more aggressive than the one in
rc1. In some tests we performed, rc1 was still consuming too much
memory.

For some programs (as you noticed), small differences in the collector
may affect speed without affecting memory usage. That is why the
collector has adjustable parameters.

Anyway, if I did the math correctly, with the standard parameters rc3
is less than 4% slower but uses 7% less memory:

* pause=200-stepmul=200 (default)
lua5.2.1-rc1       125.4~1.3s (+3.2s)  129.6~1.3s (+3.4s)  139.6~1.7s  2,056MB
lua5.2.1-rc3       130.0~0.8s (+2.9s)  134.3~0.9s (+3.1s)  141.4~0.6s  1,900MB

total time rc1: 125.4 + 3.2 = 128.6
total time rc3: 130 + 2.9 = 132.9
difference: (132.9 - 128.6) / 128.6 = 3.3%

memory rc1: 2056
memory rc3: 1900
difference: (2056 - 1900) / 2056 = 7.6%


-- Roberto