From: Charles Oliver Nutter <charles.nutter@...>
Date: 2007-07-16T16:01:47+09:00
Subject: Re: Proposal: runtime-modifying Kernel methods should be keywords

John Lam (CLR) wrote:
>> PS: Incidentally... The comment on the blog entry you gave above
>> mentions call site caches. I had a student try that for Ruby, and he
>> found that it couldn't beat Ruby's built-in cache. The reason is
>> probably the simplicity of Ruby's cache, excellent hardware cache
>> behavior, and a good cache hit-rate.
> 
> Not sure what you mean by this - are you saying that the call site method caches did not improve perf at all in a modified version of Ruby?

I imagine he means that since Ruby already has method caches in other 
forms, adding call-site caches did not help in the existing 
implementation. But that's a one-sided view point; call site caches in 
JRuby, for example, would help immensely, because it would eliminate (in 
most cases) all method lookup *and* invocation indirection. This in turn 
would enable HotSpot to much more easily inline the actual code being 
called, where having many levels of indirection between the call site 
and the target method makes it much harder. Call site caches are not 
only about avoiding method lookup in our case...they're about making 
execution as straight a line as possible.

- Charlie