Benchmarks: AMD64 vs i386 on Dual 246 Opteron

[Martin Cracauer]

ray at 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% :-)

Martin
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Martin Cracauer <cracauer at cons.org>   http://www.cons.org/cracauer/
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