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Date:      Mon, 28 Nov 2005 05:52:16 -0500
From:      Kris Kennaway <kris@obsecurity.org>
To:        Ruslan Ermilov <ru@FreeBSD.org>
Cc:        amd64@FreeBSD.org
Subject:   Re: My make buildworld FreeBSD 6.0R amd64 test
Message-ID:  <20051128105215.GA16457@xor.obsecurity.org>
In-Reply-To: <20051128104253.GB59977@ip.net.ua>
References:  <438AA21E.2030702@gneto.com> <20051128104253.GB59977@ip.net.ua>

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On Mon, Nov 28, 2005 at 12:42:53PM +0200, Ruslan Ermilov wrote:
> On Mon, Nov 28, 2005 at 07:22:22AM +0100, Martin Nilsson wrote:
> > Hi list,
> >=20
> > I made some simple comparing of CPU performance between intel and AMD=
=20
> > CPU:s on FreeBSD 6.0R The intent was to see how things like dualcore an=
d=20
> > Hyperthreading affects a rather CPU bound real world job.
> >=20
> > The results can be seen here:
> > http://www.mullet.se/support/amd64-buildworld.html
> >=20
> > Please don't publish this anywhere else, I want to have your comments=
=20
> > and a chance to fix any errors before I get slashdotted and flamed to=
=20
> > hell :-)
> >=20
> For the starters, you're compiling two different sets of files,
> one for i386 and another for amd64.  You'd better compare the
> same set.  This can be done (approximately) by doing a cross-build
> for say i386: "make -jN buildworld TARGET_ARCH=3Di386".  Also, given
> the amount of memory that you have in these machines, it shouldn't
> be a problem to put /usr/src and /usr/obj onto a memory disk.

That will only cross-compile on amd64; isn't it better to
cross-compile a third party (e.g. sparc64) on both i386 and amd64?

Also, you can get best performance by eliminating the hard disk
altogether.  This would most clearly show you any differences between
the CPU and memory hardware.  First build a (native) world, install it
into a md (swap-backed, not malloc backed, and mount the filesystems
async), mount devfs there and copy in your /etc, then copy in /usr/src
(or put it in a new md so you can get concurrent access, although this
may not be needed since a single md won't be saturated), and chroot to
the md.  Then run the cross-build.  When I tried this for fun the
other day on a 4-CPU amd64 machine it took a little over 15 minutes to
buildworld.

Kris

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