Inter-socket victim cacheing for platform power reduction

On a multi-socket architecture with load below peak, as is often the case in a server installation, it is common to consolidate load onto fewer sockets to save processor power. However, this can increase main memory power consumption due to the decreased total cache space. This paper describes inter-socket victim cacheing, a technique that enables such a system to do both load consolidation and cache aggregation at the same time. It uses the last level cache of an idle processor in a connected socket as a victim cache, holding evicted data from the active processor. This enables expensive main memory accesses to be replaced by cheaper cache hits. This work examines both static and dynamic victim cache management policies. Energy savings is as high as 32.5%, and averages 5.8%.