Optimized kernel builds: the straight dope [fp extensions]

[Paul Sladen]

On Tue, 15 Aug 2006, Pavel Rojtberg wrote:
> Matt Zimmerman wrote:
> > I'm interested to hear (objective, reasoned) feedback on this data
> Perhaps it would make sense to leave one optimized kernel on i386 for 
> newer CPUs. This could be SSE optimized [..]

The only time that the SSE/MMX units get used are on particular models of
CPU for accelerating memory-memory blit (copy) operations.  In this case
they are timed and dynamically selected on boot-up anyway.

The performance from MMX/SSE comes from userspace utilities, that again, do
on-load testing of what extensions are available---but they do actually make
use of the instruction set extensions in a useful manner;  same goes for
things like FCMOV.

	-Paul
-- 
High on a tall bridge, surrounded by noisy lorries.  Southampton, GB