>  But if you disable DMA transfers under RiscOS (*unplug DMAManager) you
>still get far higher than the 110Kps transfer rates seen under RiscBSD.
>
>  Why then are the SCSI drivers so slow?

The other thing of course is that the RiscBSD SCSI driver is in C with no
assembler. Transfer rates could probably be improved by coding the actual
transfer routines in assembly.

At a glance the sfas_ixfer() and sfasiwait() routines could probably go a lot
faster if coded in asm (Any one want to try).
One thing would be to build a profiling kernel, then do a load of SCSI stuff
and see where the kernel is spending all the time. I would guess it would be in
the two above routines.

Anyone want to code assembly versions ?

Cheers,
				Mark

-- 
Mark Brinicombe				amb@physig.ph.kcl.ac.uk
Research Associate			http://www.ph.kcl.ac.uk/~amb/
Department of Physics			tel: 0171 873 2894
King's College London			fax: 0171 873 2716