|Authors||C. H. Lunde, H. Espeland, H. K. Stensland and P. Halvorsen|
|Title||Improving File Tree Traversal Performance by Scheduling I/O Operations in User Space|
|Afilliation||Communication Systems, Communication Systems|
|Publication Type||Proceedings, refereed|
|Year of Publication||2009|
|Conference Name||Proceedings of the 28th IEEE International Performance Computing and Communications Conference (IPCCC)|
Current in-kernel disk schedulers provide efficient means to optimize the order (and minimize disk seeks) of issued, in-queue I/O requests. However, they fail to optimize sequential multi-file operations, like traversing a large file tree, because only requests from one file are available in the scheduling queue at a time. We have therefore investigated a user-level, I/O request sorting approach to reduce inter-file disk arm movements. This is achieved by allowing applications to utilize the placement of inodes and disk blocks to make a one sweep schedule for all file I/Os requested by a process, i.e., data placement information is read first before issuing the low-level I/O requests to the storage system. Our experiments with a modified version of tar show reduced disk arm movements and large performance improvements.