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Date:      Fri, 19 May 2000 17:09:04 +0530
From:      Rahul Siddharthan <rsidd@physics.iisc.ernet.in>
To:        Hans Weber <weber@mt.luth.se>
Cc:        questions@FreeBSD.ORG
Subject:   Re: gcc_debian_linux_code_on_freebsd
Message-ID:  <20000519170902.A5422@physics.iisc.ernet.in>
In-Reply-To: <392510FE.633E06F4@mt.luth.se>; from weber@mt.luth.se on Fri, May 19, 2000 at 12:01:35PM %2B0200
References:  <392510FE.633E06F4@mt.luth.se>

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> I have a rather odd problem with gcc. (version 2.95.1)
> 
> Code compiled on a Debian linux machine with gcc (2.95) is 20 %
> faster on my freebsd machine compared to if I compile on my
> freebsd machine and then run it on my freebsd machine. I have
> linux compat enabled.

Does this happen only on one of your programs, or on all of them?

It could just be a result of using different C libraries -- maybe GNU
libc/libm have faster implementations for some functions (and maybe
FreeBSD's libc/libm have faster implementations for some other
functions).  Or maybe GNU libc works a little better on SMP machines?

Unfortunately I never got around to installing gcc 2.95.x on a linux
machine. But roughly, I see comparable performance with linux/egcs
1.1.2 and freebsd/gcc 2.7.2.3 or 2.95.2 with the -O flag, and up to
20% superior performance with freebsd/gcc 2.95.2 if I use the -O2 flag
on both systems.  These are on single processor machines, and this is
with some of my code and shouldn't be taken seriously as a benchmark.

Rahul.


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