GC impact (was Re: GCC 3.3, GCC 3.4)

[Matt Austern]

On Thursday, February 6, 2003, at 10:34  PM, Tim Josling wrote:

> I did some more tests, extracting the cc1plus (c++ compliler) 
> component out of
> a gcc build
> including C++. I.e. how much CPU time did the C++ compiler use?
>
> User CPU times were
>
> Matt's minimal allocator: 114.95 seconds
> ggc-page with collection turned off: 131.55
> ggc-page unchanged: 158.48
>
> The way ggc-page allocates storage slows things down significantly. We 
> see
> that the collections also take a significant amount of time. The total 
> cost of
> GC is 37%!

This is interesting.  It looks like the main difference between your 
test
and mine is that I was measuring the time to compile C++ source (one of 
the
sample Carbon-based programs that Apple distributes with our development
tools), and you're measuring the time to compile a C source (the 
compiler).

I have no trouble believing that the performance characteristics of cc1 
and
cc1plus are different.

			--Matt