This chapter boils down to a small number of recommendations for managing a modest UML server.
Use a recent 2.6 kernel on the host. This will have performance enhancements for UML on all architectures and necessary bug fixes on x86_64 and S/390. It will give you the AIO and O_DIRECT capabilities, which UML will take advantage of.
Make sure CONFIG_MODE_TT is disabled. It is disabled in the default configuration of UML, so you likely won't have to do anything except verify this. Having CONFIG_MODE_TT disabled will give you more flexibility in the amount of physical memory you can provide to your UML instances.
Consider applying the skas3 patch to the host. This will provide somewhat better performance than skas0.
Mount a tmpfs filesystem on /tmp, or wherever you have the UML instances create their physical memory files, and make sure it is large enough to hold all of those files.
screen is an essential tool for managing long-lived UML instances. Become familiar with it.
Be careful about managing the host's physical memory. If the sum of the UML instances' physical memory sizes greatly exceeds the host's physical memory, performance will suffer as the host swaps out the UML instances. Look into techniques for reducing memory consumption such as COWing your ubd filesystem images or booting from humfs directories.
It may simplify the management of your instances to centralize their umid directories.
