Date: Sun, 22 Jun 2003 21:07:12 +0100
From: John Bradford <john@grabjohn.com>
Message-Id: <200306222007.h5MK7CS7000136@81-2-122-30.bradfords.org.uk>
To: akpm@digeo.com, hps@intermeta.de
Subject: Re: GCC speed (was [PATCH] Isapnp warning)
Cc: linux-kernel@vger.kernel.org
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1341
Lines: 31

> No, the build system is OK.  And ccache nicely fixes up any mistakes which
> the build system makes, and distcc speeds things up by 2x to 3x.
>
> None of that gets around the fact that code needs to be tested with various
> combinations of CONFIG_SMP, CONFIG_PREEMPT, different subarchitectures,
> spinlock debugging, etc, etc.  If the compiler is slow people don't bother
> doing this and the code breaks.
>
> Cause and effect.

Are the benchmarks that show gcc 3.3 to be much slower at compile time
being done with a natively compiled gcc 3.3?  I.E. gcc 3.3 compiled
with itself?

When I upgraded a few machines from 2.95.3 to 3.2.3, I noticed that
the last of the three compiles, (I.E. a gcc-3.2.3 compiled gcc-3.2.3
compiling the gcc-3.2.3 source), was noticably quicker than the first
two, to the extent that it was easily mesaurable by a wall clock.

I am just wondering whether there gcc-3.X binaries in use that were
compiled with gcc-2.95.3, that are swaying benchmarks in favour of
2.95.3 compiled with itself.

I haven't benchmarked gcc-2.95.3 compiled with gcc-3.2.3, though.

John.
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