sritchie@cs.ubc.ca (Stuart Ritchie) (06/28/91)
Many CISC CPUs (eg. 68k, '386) have instructions that do "bulk saves" of the processor registers. The 88k does not appear to have such a facility, but being a RISC chip this is probably not surprising. However, the 88k certainly does have its fair share of registers. The average context switch might cost ~80 instructions just to save and restore the pertinent registers! Pipelining and caching probably has a big effect on this, but does anybody have any numbers on how expensive basic context switching is? If anyone has any context switching code that they could share with me, I would be grateful. I would really like to hear from people doing any kernel hacking... anyone doing Mach ports or some such thing? I have just started on a fairly large 88k kernel project using the MVME188 hardware, and would really like to gain some contacts with people who are up there on the learning curve... Eagerly awaiting your posts or replies, Stuart