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- Grahn, Håkan, et al.
(författare)
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A Comparative Evaluation of Hardware-Only and Software-Only Directory Protocols in Shared-Memory Multiprocessors
- 2004
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Ingår i: Journal of Systems Architecture. - : Elsevier BV. - 1383-7621. ; 50:9, s. 537-561
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Tidskriftsartikel (refereegranskat)abstract
- The hardware complexity of hardware-only directory protocols in shared-memory multiprocessors has motivated many researchers to emulate directory management by software handlers executed on the compute processors, called software-only directory protocols.In this paper, we evaluate the performance and design trade-offs between these two approaches in the same architectural simulation framework driven by eight applications from the SPLASH-2 suite. Our evaluation reveals some common case operations that can be supported by simple hardware mechanisms and can make the performance of software-only directory protocols competitive with that of hardware-only protocols. These mechanisms aim at either reducing the software handler latency or hiding it by overlapping it with the message latencies associated with inter-node memory transactions. Further, we evaluate the effects of cache block sizes between 16 and 256 bytes as well as two different page placement policies. Overall, we find that a software-only directory protocol enhanced with these mechanisms can reach between 63% and 97% of the baseline hardware-only protocol performance at a lower design complexity.
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