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