If you have more than one child, you’ve probably heard yourself say things like “if you are not using your train, you should let your brother play with it” more often than you’d like. The same happens in a datacenter (minus the screams and tears, at least usually). In that context, the rivaling siblings take the form of guest virtual machines and the toys in contention are the physical resources of the host system: CPU, I/O, memory. While virtualization platforms do a pretty good job at efficiently sharing the first two, the situation is not nearly as good for memory. It is often, as a result, the limiting factor for virtualization-driven consolidation. A new project aims to fix this.
The Oracle engineers working on the Xen-based Oracle Virtual Machine have just announced a new open source (GPL-licensed) project to improve the sharing of physical memory between guest virtual machines on the same physical system. It’s called Transcendent Memory, or tmem for short.
Much more information, including a comparison with VMWare’s memory balloon, is available from the project home page.
Another reason to come to the upcoming Xen Summit (February 24 and 25), hosted by Oracle here at headquarters.