Monitoring Memory Behaviors and Mitigating NUMA Drawbacks on Tiered NVM Systems.

Non-Volatile Memory with byte-addressability invites a new paradigm to access persistent data directly. However, this paradigm brings new challenges to the Non-Uniform Memory Access (NUMA) architecture. Since data accesses cross NUMA node can incur significant performance loss, and, traditionally, OS moves data to the NUMA node where the process accessing it locates to reduce the access latency. However, we find challenges when migrating data on NVM, which motivates us to migrate the process instead. We propose SysMon-N, an OS-level sampling module, to obtain access information about NVM in low overhead. Furthermore, we propose N-Policy to utilize the data collected by SysMon-N to guide process migration. We evaluate SysMon-N and N-Policy on off-the-shelf NVM devices. The experimental results show that they provide 5.9% to \(3.62\times \) bandwidth improvement in the case where cross-node memory accesses happen.