A xrun happens in Linux when software and hardware get out of sync. A common place to find them is in audio, in which the software reads a buffer faster then the operating system can keep it filled. But it could also happen if software was to slow at reading the buffer. Xruns usually signify latency problems, and can be caused by a overstressed system. Xruns are also usually a software problem related to the CPU and I/O schedulers.
- Increasing performance tips to unstress a system.