I have noticed a bug with Ubuntu 14.04.4 LTS; if the NFS client loses connection to the NFS server the load on that system will spike to upwards of 30.
The only way I've noticed to bring the load down is to lazily unmount the NFS share:
umount -l /path/to/share
The problem is; all the conventional tools to tell me system resource usage are not helpful:
mpstat indicate that there is nothing wrong with the system; no single process or thread is running that could explain why the load is so high.
My assumption is that since NFS is implemented in the kernel in Linux is that these tools simply can't see what's going on; is there a way to better troubleshoot this issue? As the conventional tools seem to not work. Is there a way to monitor the run queue in Linux?