The operating system needs page access history for swapping. However it can only be approximated by clearing access bit in page table entry periodically. With HMTT, each off-chip memory access can be captured online. Thus infact we can get a detailed access history page by page.

There remains a problem for HMTT to transfer the history information back to the host. The gigabit ethernet port can be used for this purpose. There will be micro-seconds level delay but is enough for OS to make decision.

We have used this technology in our research on page de-duplicationin KVM . Please see:

Licheng Chen, Zhipeng Wei, Zehan Cui, Mingyu Chen, Haiyang Pan, Yungang Bao,"CMD: Classification-based Memory Deduplication through Page Access Characteristics",the 10th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments(VEE14),Salt Lake City, UT,March 1-2,2014