Clocking and synchronization within a fault-tolerant multiprocessor
H Krauss · NASA STI Repository (National Aeronautics and Space Administration) · 1972
I n t h i s t h e s i s t h e synchronization requirements of a f a u l t -t o l e r a n t multiprocessor are defined and methods of maintenance of synchronism a r e developed.I t is demonstrated t h a t a synchronous f a u l t -t o l e r a n t multiprocessor driven by a f a u l tt o l e r a n t clock i s more e f f i c i e n t and more e a s i l y implemented than i s an asynchronous f a u l t -t o l e r a n t multiprocessor.F a u l t -t o l e r a n t clocking has been examined i n t e n s i v e l y here.From f a u l t -t o l e r a n c e requirements and t h e e s t a b l i s h e d multiprocessor synchronization requirements, general s p e c i f ic a t i o n s a r e developed f o r a f a u l t -t o l e r a n t clock.Two general methods of design have been explored, and it has been concluded t h a t i f the clock is t o be d i s t r i b u t e d t o many modules, faulttolerant clocking through the concepts advanced by William Daly and John McKenna of t h e C.S. Draper Laboratory, is more p r a c t ic a l t o implement than is f a u l t -t o l e r a n t clocking through f a i l u r ed e t e c t i o n and subsequent clock s u b s t i t u t i o n .by Daly and McKenna have been examined, refined, and r e v i s e d , I t i s demonstrated t h a t it i s desirable t o have a v a i l a b l e a f a u l t -t o l e r a n t clock which runs a t 20 M H z , but t h a t such a frequency is not achieveable by a McKenna-type clock (with use of c u r r e n t technology).A method of achieving the use of a r e l a t i v e l y slow McKenna-type clock i n conjunction with a f r equency m u l t i p l i e r is developed.Also, analog phase-locking techniques a r e shown t o be unsuitable f o r the design of a f a u l tt o l e r a n t clock.