From: Daniel DeLorme <dan-ml@...42.com>
Date: 2008-03-13T09:48:17+09:00
Subject: Re: Copy-on-write friendly garbage collector

Hongli Lai wrote:
> Great work Daniel. I don't measure the same amount of speedup that you 
> claim in your email, but there is definitely a small speedup.
> 
> I've added some further further optimizations. 
> find_position_in_bitfield() now uses bit operators instead of division 
> and modulo operators. This should speed things up a little more.
> 
> The attached patch is created against Ruby 1.8, but it shows what I've 
> exactly changed.

Thank you. I also looked at find_position_in_bitfield() but I assumed 
the compiler would be able to make those optimizations, so ended up not 
touching it.

I notice that this patch is relative to one of the patches that I 
submitted. But in those patches I changed the bsearch to a linear 
search, which may not be desirable as Matz pointed out. But I'm not sure 
it's a good idea to sacrifice performance now for the sake of a 
hypothetical change in heap size in the future (YAGNI). Maybe a #define 
could take care of that? e.g.
   #ifdef FEW_HEAPS
     order heaps by size, linear search
   #else
     order heaps by memory location, bsearch
   #endif

--
Daniel