Look before you leap: An Access-based Prudent Page Migration for Hybrid Memories

Hybrid memory composed of DRAM and PCM exploits benefit of both types of memory. The random page placement in such memories may cause write-intensive pages to be placed in PCM partition, which may adversely affect the memory performance due to the higher write latency of PCM. Migration of write-intensive pages to DRAM helps in improving memory service time. Existing techniques migrate pages having write access count greater than a predefined threshold. These techniques do not examine the access pattern once the choice to migrate the page has been made. This might lead to unnecessary migrations because the page may have been hot before the decision, but the number of access may have dropped after migration. To accurately identify the hot page, we propose an access-based prudent page migration method which uses an eDRAM buffer to migrate hot pages from PCM to DRAM. In this paper, we present a look-before-you-leap migration technique where after a page is identified as a hot page, makes a thoughtful decision regarding whether to migrate or not to migrate it.