>How much of a problem is having to clean the cache on every context switch?
>How much of the total time goes simply into cleaning the cache?

code wise it is simple but the clean could take as long as 500us I believe and
ints are off during this time so horrible irq latency ;-(

>Presumably if it has to do it both on context switches and on recieving
>interrupts it's quite a lot!

I dont need to clean on an interrupt but some cleaning is needed when ever any
pages are remapped due to having a virtual cache.

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