Re: compiling linux kernels with GCC 3.0

[Paolo Carlini <pcarlini at unitus dot it>]

Mark Mitchell wrote:

> > Is it true that there is no real evidence of performance improvements on
> > x86? If so, *why* in your (authoritative) opinion?
>
> I am not an expert on these issues.  I am the Release Manager, not the
> all-knowing mastermind of GCC. :-)

:-)

> I have heard reports of improvements, I have heard reports of
> pessimizations.  I do not have authoritative information one way or
> the other.

So, *who* has it?

The GCC project is proud of his regression testsuite. On the other hand I see
that there is an increasing attention to the reference benchmarks (e.g., Diego
Novillo and Andreas Jaeger running SPEC95 and SPEC2000).

Do you believe that a form of regression *performance* testing could be viable?

> We have to make tradeoffs between features and optimizations.
>
> GCC 3.0 was primarily a feature release; I hope that 3.1 will focus
> more on optimizations.

Of course. But perhaps that was not so clear reading the 3.0 highlights?

  - Support for Java, including the GNU implementation of the Java
    run-time library.

  - A new x86 back-end, which generates faster code.

  - A more efficient, more standards-compliant C++ compiler,
    using an industry standard C++ ABI.

  - A new, standards-conformant, implementation of the C++ standard
    library.

  - Improved optimizations.

  - Improved documentation.


Anyway, thanks for your attention and for your work, of course,
Paolo Carlini.