Re: GCC 3.3, GCC 3.4

[Matt Austern <austern at apple dot com>]

On Tuesday, February 4, 2003, at 12:11 PM, Tim Josling wrote:

> 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?
My placeholder "collector"  is attached.  Note that you can't use
it with PCH; doing a PCH experiment might be interesting too,
but it would be harder.  I also made the obvious changes in the
configure script and makefile to accept --with-gc=placeholder.

As you can see, I'm doing things in the maximally simpleminded
way.

Attachment: ggc-placeholder.c
Description: Text document

Attachment: Makefile.in
Description: Binary data

Attachment: configure.in
Description: Binary data

The test was with the top of Apple's CVS tree at the time I did it,
which was about a month ago.  It's pretty similar to the current
top of the 3.3 release branch, but if you feel like being really precise
and going to Apple's CVS server, the tag to look at is gcc3-1310.

> Also did you keep your actual numbers, and what was your machine
> configuration.
I tested running cc1plus only, on a preprocessed source file.  I don't
think I can include that source file, I'm afraid, because it's 
proprietary
Apple code.  I was running the tests on a PPC running OS X
10.2.2.

Numbers:
TOT						2.6s real, 2.3s user, 0.3s sys
TOT with placeholder gc		2.3s real, 2.0s user, 0.3s sys

The numbers changed a bit depending on how large the chunks were
that I allocated with ggc-placeholder.c.  I can probably find some more
detailed numbers if I try.

And I have to say, these results surprised me.  I expected to see bigger
gains, because of improved locality.

			--Matt