Section 8.3

Section 8.3

Posted Nov 22, 2007 22:38 UTC (Thu) by anton (guest, #25547)
Parent article: Memory part 8: Future technologies

FB-DRAM has already been deployed for quite some time in current multi-socket Xeon systems, and IIRC also in Niagara-based Suns. However, the high power consumption and heat dissipation of FB-DIMMs leads Intel to also provide Dual-Xeon chipsets that support plain registered DIMMs; unfortunately, the higher pin count of the regular DDR2 interface mean that this chipset supports only two channels instead of four. AMD still has an advantage here (two DDR2 channels per socket).

Concerning Cell SPUs and memory latency: the SPUs can only access their local memory (256KB), not the main memory. If data or code needs to be loaded into the local memory, software has to program the transfer from main memory explicitly (unlike cache, which is automatic). So, yes, explicit prefetching is necessary, otherwise the SPU won't get it's data at all.

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