On Mon, 2005-Mar-28 23:23:19 -0800, David Leimbach wrote: >meant to send this to the list too... sorry >> Are you implying DragonFly uses FPU/SIMD? For that matter does any kernel? > >I believe it does use SIMD for some of it's fast memcopy stuff for >it's messaging system >actually. I remember Matt saying he was working on it. > >http://leaf.dragonflybsd.org/mailarchive/kernel/2004-04/msg00262.html
That's almost a year ago and specifically for the amd64. Does anyone know what the results were? >If you can manage the alignment issues it can be a huge win. For message passing within the kernel, you should be able to mandate alignment as part of the API. I see the bigger issue being the need to save/restore the SIMD engine's state during a system call. Currently, this is only saved on if a different process wants to use the SIMD engine. For MMX, the SIMD state is the FPU state - which is non-trivial. The little reading I've done suggests that SSE and SSE2 are even larger. Saving the SIMD state would be more expensive that using integer registers for small (and probably medium-sized) copies. -- Peter Jeremy _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"