GCC 3.3, GCC 3.4

[Tim Josling]

Devang Patel wrote:

> > Tests I did last year showed that even without doing collection, gcc
> > is slowed
> > down by the requirements of GC...
> >
> 
> Matt Austern at Apple did similar experiment by using ggc placeholder.
> (same interface as ggc, no collection, allocate memory using mmap in
> chunks and
> satisfy memory allocation requests from these chunks etc..).
> 
> He got around ~12% speedup for sample c++ source.
> 
> -Devang

> (also from Geoff Keating in another email)


> 
> To be precise, Matt found that the speedup of using the ggc
> placeholder was about equivalent to the speedup of using ggc-page but
> disabling garbage collection.  This contradicts the results that Tim
> Josling got above.
> 
> -- 
> - Geoffrey Keating <>

Geoffrey,

The first rule of performance testing is to change one thing at a time. Here
we have several variables:

gcc code versus unspecified c++ code.
Matt's versus Tim's minimal non-gc implementation.
Different machine/cpu/OS (presumably).

I will dig out my minimal implementation and post it as a patch, so people can
verify my numbers for themselves. 

Matt,

Any chance I could get a copy of your c++ source and/or your minimal non-gc
implementation so I can see what is under the discrepancy?

Also did you keep your actual numbers, and what was your machine
configuration. 

I have a PIII with 256 mb ram, running gnu/linux 2.4 (Red Hat 7.1), but I did
not keep the actual numbers.

Tim Josling