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| Some testing results show that on average 67% of broadcasts for the maintenance of cache coherence in SMP systems are unnecessary. To reduce the unnecessary overhead of snoopy-based embedded SMP systems, this paper proposes a new software/hardware hybrid cache coherence optimization—the programmer can insert special instructions into programs to direct related hardware to enable/disable broadcast operations, so some potential broadcasts for unshared variables are avoided without violating data coherence. We design the mechanism along with a proposed coherence protocol. Moreover, it is simulated on a SMP simulation platform and the results show that the improvement is apparent. Although the insertion is manual, we believe it accords with the existing SMP programming model. |
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| Keywords:SMP, cache coherence, snoopy-based protocol |
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