Carsten Langgaard (carstenl@mips.com) writes: > I think we have a problem with the PREF instructions spread out in the > memcpy function. Not really. The MIPS32 manual (for example): "PREF does not cause addressing-related exceptions. If it does happen to raise an exception condition, the exception condition is ignored. If an addressing-related exception condition is raised and ignored, no data movement occurs." PREF never generates a memory operation for a location with an uncached memory access type." For a Linux user program, at least, memory pages are "memory-like": reads are guaranteed to be side-effect free, so any outlying prefetches are harmless. It's hard to see any circumstance where an accessible cacheable location would lead to bad side-effects on read. -- Dominic Sweetman, MIPS Technologies (UK) - formerly Algorithmics The Fruit Farm, Ely Road, Chittering, CAMBS CB5 9PH, ENGLAND phone: +44 1223 706200 / fax: +44 1223 706250 / direct: +44 1223 706205 http://www.algor.co.uk
