> Current CVS kernel uses FPU emulator unconditionally. If one floating
> point intruction causes a 'Unimplemented' exception (denormalized
> result, etc.) following floating point instructions are also handle by
> FPU emulator (not only the instruction which raise the exception).
> I do not know this is really desired behavior, but here is a patch to
> change this. If Unimplemented exception had been occured during the
> benchmark, aplying this patch may result better performance.
Not desired behavior, just an artifact. However, I agree with Carsten
that changing the API to the emulator for this and using a counter
as you have done is not appropriate, and that the existing CPU
configuration flag is a more appriate mechanism. It's possible
that Wayne's baseline numbers came from a pre-Algor-emulator
kernel, and that this "feature" accounts for some of his degraded
performance. But I'd be surprised if it accounted for all of it,
unless his FP test does 10% of its calculations on denormalized
numbers or something.