I've recently encountered a very annoying effect: when a process on Xen DomU apparently consumes all available RAM/swap (that's my assumption; the root of the problem might lie elsewhere), the DomU locks up, becomes totally unresponsive, and the only way to bring it back online is to login to Dom0 and destroy/recreate the VM. A typical part of the console log of DomU follows:
[88751.207692] INFO: task cron:1318 blocked for more than 120 seconds. [88751.207717] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [88875.710604] Out of memory: kill process 1315 (apache2) score 51765 or a child [88875.710655] Killed process 1315 (apache2)
Dom0 is Debian Lenny; DomU is Ubuntu Jaunty. Xen version is 3.1.
- What may cause such behavior?
- What tests should I make to help figure it out?
- What configuration options (such as RAM or VCPU distribution between the Dom0 and the DomU) can possibly solve the problem?