Cache Coherence Using Local Knowledge Cache Coherence Using Local Knowledge

Typically, commercially available shared memory machines have addressed the cache coherence problem with hardware strategies based on global inter-cache communication. However, global communication limits scalability and eeciency. \Local knowledge" coherence strategies, which avoid global communication at run-time, ooer better scal-ability, at the cost of some additional cache misses. The most eeective local knowledge strategies described in the literature are those based on generation time-stamps (TS). We propose a new strategy, TS1, that requires less extra storage than TS, only one extra bit per cache line, and can produce more cache hits by exploiting sophisticated compiler analysis. TS1 handles common synchronization paradigms including DOALL, DOACROSS, and critical sections. Early results show TS1 is, worst case, slightly slower than TS. Best case, TS1's exibility allows for signiicant improvements.