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Date: Sat, 26 Jan 2002 17:48:00 +0000
From: Jamie Lokier <lk@tantalophile.demon.co.uk>
To: Jeff Garzik <jgarzik@mandrakesoft.com>
Cc: Martin Eriksson <nitrax@giron.wox.org>,
        Linus Torvalds <torvalds@transmeta.com>, linux-kernel@vger.kernel.org
Subject: Re: [ACPI] ACPI mentioned on lwn.net/kernel
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Jeff Garzik wrote:
> > Hmm.. I tried to compile the kernel with -Os (gcc 2.96-98) and I just got a
> > ~1% smaller vmlinux and a ~3% smaller bzImage. Maybe the size optimizations
> > doesn't show on these files? Internal data structures that are much bigger
> > than "real" code?
> 
> That doesn't tell us much unless you benchmark any speed
> improvements/degradations noticed.  Hidden in that 1% may be more
> favorable I-cache usage, better register usage... who knows.
> 
> It would also be interesting to compile key files like kernel/sched.c or
> mm/vmscan.c in assembly using O2 and Os, and compare the output with
> diff -u.

It'd be good to know why it's not achieving the quoted 30% space saving
that other compilers manage for normal code, unless it's myth of course.

-- Jamie
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