Optimizing Replication, Communication, and Capacity Allocation in CMPs

Chip multiprocessors (CMPs) substantially increase capacity pressure on the on-chip memory hierarchy while requiring fast access. Neither private nor shared caches can provide both large capacity and fast access in CMPs. We observe that compared to symmetric multiprocessors (SMPs), CMPs change the latencycapacity tradeoff in two significant ways. We propose three novel ideas to exploit the changes: (1) Though placing copies close to requestors allows fast access for read-only sharing, the copies also reduce the already-limited on-chip capacity in CMPs. We propose controlled replication to reduce capacity pressure by not making extra copies in some cases, and obtaining the data from an existing on-chip copy. This option is not suitable for SMPs because obtaining data from another processor is expensive and capacity is not limited to on-chip storage. (2) Unlike SMPs, CMPs allow fast on-chip communication between processors for readwrite sharing. Instead of incurring slow access to read...

• Type: Conference
• Year: 2005
• Where: ISCA
• Authors: Zeshan Chishti, Michael D. Powell, T. N. Vijaykumar
• Keywords: Already-limited On-chip Capacity, Capacity Pressure, Fast Access, Hardware, ISCA 2005