DFBuffer: High-performance data forwarding software optimized for single-process I/O scenarios

Most supercomputers adopt a data forwarding architecture to achieve storage scalability. However, it results in a significant reduction in single-process bandwidth compared to direct file system access. Moreover, considering that a majority of applications uses only a single process for writing and reading data, the low single-process performance also leads to a time overhead for these applications. This paper proposes an userspace forwarding mechanism DFBUFFER with two performance optimization methods: user-space multi-thread request processing and data write buffer in a unit of file. The client of DFBUFFER is embedded in the application as a library reducing the software overhead, and the server implements multi-thread I/O request processing to improve bandwidth efficiency. The data write buffer can asynchronously handle write requests, which accelerates the write bandwidth of compute nodes. We evaluate DFBUFFER on the Sunway exascale prototype system. The results indicate that in the regular mode of DFBUFFER, both the write and read latency are reduced, and the write bandwidth and large-block read bandwidth of single-process are increased by 1.8 times and 2.8 times respectively. The DFBUFFER buffer mode increases the write bandwidth of a single process by 0.8 times over the regular mode. Although the performance advantage of the regular mode of DFBUFFER gradually weakens with the increase of concurrent processes, the DFBUFFER buffer mode has the effect of improving the write bandwidth, the 64-IO-processes application is increased by 0.2 times.