Masking I/O latency using application level I/O caching and prefetching on Blue Gene systems

In this paper, we present an application-level I/O caching, prefetching, asynchronous system to hide access latency experienced by HPC applications. Our solution of user controllable caching and prefetching system maintains a file-IO cache in the user space of the application, analyzes the I/O access patterns, prefetches requests, and performs write-back of dirty data to storage asynchronously. So each time the application needs the data it does not have to pay the full I/O latency penalty in going to the storage and getting the required data. We have implemented this caching and asynchronous access system on the Blue Gene (BG/L and BG/P) systems. We present experimental results with NAS BT, MADbench, and WRF benchmarks. The results on BG/P system demonstrate that our method hides access latency, enhances application I/O access time by as much as 100%, and improves WRF execution time over 10%.