From: ts <decoux@...>
Date: 2003-01-01T20:57:41+09:00
Subject: Re: [1.8] speed

>>>>> "K" == Kero van Gelder <kero@chello.nl> writes:

K> gc_sweep() got called for each allocation of 100kB, meaning it was ran
K> about 100 times more often for 1.7.3 than for 1.6.8. If I change the
K> allocation size to 100 bytes (instead of 100 kB) 1.7.3 speeds up to match
K> 1.6.8

 Well, the problem is easy to understand if you look the source.

 The patch is described 

n> 	* gc.c (ruby_xmalloc, ruby_xrealloc): restrict total allocation
n> 	  size according to memories consumed by live objects.
n> 	  [ruby-dev:18482]

n> 	* gc.c (gc_sweep): estimate how live objects consume memories.

 Unfortunately this is wrong : ruby don't estimate the size of *all*
 objects but only the size of *some* objects (like T_OBJECT, T_ARRAY, ...)  
 it don't even try to correct this value to have a real estimation of the
 memory, and even if it will try do it it will have a problem.

 The problem is that ruby has selected a subpopulation and this
 subpopulation is not representative of all objects.



Guy Decoux