Ex-Tmem: Extending Transcendent Memory with Non-volatile Memory for Virtual Machines

Virtualization and multicore technology now make Transcendent memory, or Tmem, is a new approach to it possible to consolidate heterogeneous workloads on one physical optimize RAM utilization in a virtual environment where machine. Such consolidation helps reduce the amount of idle underutilized RAM from each guest VM and RAM unassigned resources. In particular, transcendent memory is a recent idea to to any guest (fallow memory), are collected into a central pool gather idle memory into a pool that is shared by virtual machines at hyper visor (or VMM), that is shared by VMs. It can be (VMs). However, the size of transcendent memory is unstable and viewed as a new level in the memory hierarchy for VMs, frequently fluctuates with changing workloads. Contention among between main memory and disks. VMs over transcendent memory can cause increased cache misses. In this paper, we propose a mechanism to extend transcendent memory (called Ex-Tmem) by using emerging non-volatile memory. Ex-Tmem stores clean pages in a two-level buffering hierarchy with locality-aware data placement and replacement. In addition, Ex-Tmem enables memory-to-memory swapping by using non-volatile memory and eliminates expensive I/O caused by swapping. Extensive experiments on implemented prototype indicate that Ex-Tmem improves performance by up to 50% and reduces disk I/O by up to 37%, compared to existing Tmem.