What causes filesystem latency?
Latency, as we discussed in Chapter 9, is the single most important metric in any performance measurement and analysis. From the filesystem’s perspective, latency is measured as the time from which a logical request was initiated to the time it was completed on the physical disk.
The latency endured because of the bottlenecks in physical storage is one factor that adds to overall filesystem response time. However, to reiterate our discussion from the previous section, as filesystems do not simply hand over an I/O request to the physical disk, latency can be experienced in more than one way, such as the following:
- Resource contention: If multiple processes concurrently write to a single file, then this can impact filesystem performance. File locking can be a significant performance issue for large applications, such as databases. The purpose of locking is to serialize access to files. Filesystems in Linux use the generic VFS methods...
