Systems Performance: Enterprise and the Cloud

8. File Systems

When studying application I/O performance, the performance of the file system matters more than disk performance. File systems use caching, buffering, and asynchronous I/O to avoid subjecting applications to disk-level (or remote system) latency. Nevertheless, performance analysis and the available toolsets have historically focused on the performance of the disks.

In the era of dynamic tracing, file system analysis is now easy and practical. This chapter shows how file system requests can be examined in detail, including the use of dynamic tracing to measure start to completion time from the application context. This often allows file systems, and their underlying disk devices, to be quickly ruled out as the source of poor performance, ...