Performance Implications of Cache Flushes for Non-Volatile Memory File Systems

The adoption of non-volatile memory as main memory has recently been proposed in computer architecture community, expecting many aspects of computer systems to be changed. One of the noticeable prospects is that a cache flush could play a major role to ensure data consistency in the proposing architecture. We investigate clflush and epoch barrier in order to take account of compatibility of those mechanisms with the new architecture. Our simulation shows that clflush requires 128ms to complete our 64M workload, corresponding to 197% raises in execution time compared to the baseline performance. Additionally, it takes 73ms to execute the same workload with epoch barrier, which indicates that the epoch mechanism slows the performance down by 69%. Although utilizing the epoch method seems to decelerate less than using clflush, it could potentially induce system degradation due to the fact that it occasionally provokes a number of write-back operations at once. This evaluation is expected to help guide further studies on reliability mechanisms in the upcoming system.