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The Scalable I/O (SIO) Initiative’s Low-Level Application Pro- gramming Interface (SIO LLAPI)provides file system implementers with a simplelow-Level interface to support high-level parallel I/O interfaces efficiently and ef fectively. This paper describes a reference implementation and the evaluation of the SIO LLAPI on the Intel Paragon multicomputer. The implementation provides the file system structure and striping algorithm compatible with the Parallel File System (PFS) of Intel Paragon, and runs either inside the kernel or as a user level library. The scatter-gather addressing read/write, asynchronous I/O, client caching and prefetching mechanism, file access hint mechanism, collective I/O and highly efficient file copy have been implemented. The preliminary experience shows that the SIO LLAPI provides opportunities of significant performance improvement and is easy to implement. Some high level file system interfaces and applications, such as PFS, ADIO and Hartree-Fock application, are also implemented on top of SIO. The performance of PFS is at least the same as that of Intel’s native PFS, and in many cases, such as small sequential file access, huge I/O requests and collective I/O, it is stable and much better. The SIO features help to support high level interfaces easily, quickly and more efficiently, and the cache, prefetching, hints are useful to get better performance based on different access models. The scalability and per formance of SIO are limited by the network latency, network scalable bandwidth,memory copy bandwidth, memory size and pattern of I/O requests. The tradeoff between generality and efficiency should be considered in implementation.
The Scalable I / O (SIO) Initiative’s Low-Level Application Pro-gramming Interface (SIO LLAPI) provides file system implementers with a simple low-level interface to support high-level parallel I / O interfaces efficiently and efectively. This paper describes a reference implementation and the evaluation of the SIO LLAPI on the Intel Paragon multicomputer. The implementation provides the file system structure and striping algorithm compatible with the Parallel File System (PFS) of Intel Paragon, and runs either inside the kernel or as a user level library The scatter-gather addressing read / write, asynchronous I / O, client caching and prefetching mechanism, file access hint mechanism, collective I / O and highly efficient file copy have been implemented. The preliminary experience shows that the SIO LLAPI provides opportunities of significant performance improvement and is easy to implement. Some high level file system interfaces and applications, such as PFS, ADIO and Hartree-Fock applicati ... on, are also implemented on top of SIO. The performance of PFS is at least the same as that of Intel’s native PFS, and in many cases, such as small sequential file access, huge I / O requests and collective I / O, it The stable and much better. The SIO features help to support high level interfaces easily, quickly and more efficiently, and the cache, prefetching, hints are useful to get better performance based on different access models. The scalability and per formance of SIO are limited by the network latency, network scalable bandwidth, memory copy bandwidth, memory size and pattern of I / O requests. The tradeoff between generality and efficiency should be considered in implementation.