Performance comparison, ULE vs 4BSD and AMD64 vs i386

David O'Brien obrien at
Wed Feb 25 10:28:18 PST 2004

On Tue, Feb 24, 2004 at 01:58:47PM -0800, Brooks Davis wrote:
> > How about AMD64 being slower than i386 on the same hardware? By
> > slower, I mean a buildworld -j4 took about 400 seconds longer in AMD64
> > mode.
> You can't usefully compare compile times when you are compiling for
> a different instructions set.  The work involved is rairly the same
> so the results are meaning less.  If you could factor out the cost of
> building the native bootstrap tools since that isn't the same job on
> each machine, the speed of a cross buildworld would be an intresting
> test.  For comparing i386 and amd64, I'd probably build an alpha or
> sparc64 world so the target would be entierly different.

While generally true (everyone used to compare i386 & Alpha); the 80% of
the amd64 instruction set is the i386 instruction set, and most of the
code generation code is shared between the two.

-- David  (obrien at

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