Transcendent Memory: Not just for virtualization anymore!

This proposal has been rejected.


One Line Summary

New approach for dynamically optimizing physical memory utilization in the kernel, between multiple physical machines, and between VMs


RAM is “cheap”. Or is it? If a million machine data center could cut RAM in half, how much could be saved, in capital equipment cost and power/cooling expense?

Transcendent Memory (or “tmem”) is a new approach for flexibly, dynamically, and efficiently managing physical memory. First conceived to facilitate the optimization of physical memory utilization among a set of guests in a virtualization environment (and implemented in Xen 4.0), tmem has now been applied in the kernel to dynamically compress page cache and swap pages (“zcache”), and investigations are underway to dynamically hot-plug memory among a set of kernels (“RAMster”) and more effectively utilize future memory-extension technologies. All this with very minimal changes to the kernel required.

We will describe why RAM is no longer cheap, explain the basics of Transcendent Memory including the kernel changes, and show how tmem can provide unprecedented flexibility toward optimizing RAM utilization in future data centers.


kernel, memory management, resource optimization


  • Dan Magenheimer

    Oracle Corp


    Dan Magenheimer is a consulting developer for Oracle Corporation working from his home in Fort Collins, Colorado, USA, on the Linux kernel and “Oracle VM”, Oracle’s Xen-based virtualization product. Dan’s current focus is optimizing physical memory utilization.

    Prior to Oracle, Dan worked for HP for over 25 years, most recently as a principal research scientist at HP Labs. Dan began at HP as a member of the processor architecture team that developed PA-RISC; he wrote the first PA-RISC simulator, remote debugger, object-code emulator (for the 16-bit HP3000), integer multiplication algorithm, and linker. During the later 1980’s and the 1990’s, he managed various R&D teams in HP’s software, server, and storage divisions. In 2001, Dan joined an HP Labs team investigating security and virtualization on the Itanium platform; this team developed vBlades, the first Itanium virtual machine monitor. Later, Dan ported Xen to Itanium and was the first maintainer for the Xen/ia64 project.