Date: Fri, 29 Jul 2005 15:47:13 -0600 From: Ken Gunderson <kgunders@teamcool.net> To: freebsd-amd64@freebsd.org Subject: Re: Benchmarks: AMD64 vs i386 on Dual 246 Opteron Message-ID: <20050729154713.48b3fe08.kgunders@teamcool.net> In-Reply-To: <20050729083844.A78480@cons.org> References: <3.0.1.32.20050729023234.00a8afb8@pop.redshift.com> <20050729083844.A78480@cons.org>
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On Fri, 29 Jul 2005 08:38:44 -0400 Martin Cracauer <cracauer@cons.org> wrote: > ray@redshift.com wrote on Fri, Jul 29, 2005 at 02:32:34AM -0700: > > At 07:35 PM 7/28/2005 -0400, Martin Cracauer wrote: > > | > While this sounded like a long shot, I loaded FreeBSD 5.4 i386 on the machine > > | > and after applying the exact same configuration to the OS, Apache, PHP and > > | > MySQL, re-ran the benchmarks. Much to my surprise, just changing the OS > > from 64 > > | > bit to 32 bit caused the machine to double in speed. The results are attached > > | > in an Excel spreadsheet. So the exact same machine, running the identical > > | > configuration, performed roughly twice as fast when running FreeBSD 5.4 i386 vs > > | > FreeBSD 5.4 AMD64. Something about this seems so wrong to me :-) > > | > > | I'm sorry but I cannot support these findings. I don't have > > | cut'n'paste numbers handy, but generally 64 bits speed up things quite > > | a bit for me. I have seen slowdown in 64 bit mode in e.g. bzip2 but > > | generally there is a speedup. > > > > On the AMD64, I am pretty sure that I did *not* include the following lines like > > I normally do on the i386: > > > > options SMP # Symmetric MultiProcessor Kernel > > device apic # I/O APIC > > I occurse to me that not using one of the two CPUs might have > something to do with a performance drop of approximately 50% :-) Not to beat a dead horse here, but for the record, the numbers I reported were definitely for a SMP kernel. -- Best regards, Ken Gunderson Q: Because it reverses the logical flow of conversation. A: Why is putting a reply at the top of the message frowned upon?
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