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Derek Glidden: An analysis of three Linux kernel VM systems

Nov 02, 2001, 17:57 (6 Talkback[s])
(Other stories by Derek Glidden)
"There has been a lot of discussion lately, both on lkml and elsewhere, regarding the VM subsystem used in the 2.4 series of the Linux kernel. Recently, these issues have been dramatically inflated by Linus replacing the entire VM (originally built by Rik van Riel) with a whole new VM system by Andrea Arcangeli in the midst of a "stable" kernel series, specifically with the 2.4.10 kernel release.

Linus believes the new VM is more stable and "correct" than the old one. Others, including Alan Cox, believe that Rik's VM is a good direction and changing directions in the midst of a stable kernel series is a bad idea. Still others just want to know "which one is best."

This paper is not intended to answer any questions regarding whether or not it was a good idea to replace the VM in a stable kernel. Rather, it is an analysis done by a somewhat atypical "power user" who uses Linux personally and at work to do all manner of computing tasks (i.e. everything) and who wanted to understand first-hand typical performance issues relating to both of the 2.4 series VM systems in comparison with each other and in comparison with the previous "stable" VM system from the 2.2 kernel series.

This is also not indended to deal with issues regarding the 2.4 VM systems prior to what are "current" versions at the time of this writing. Several issues were floating around for some time in early 2.4 kernels that have since been fixed. People running distros that use one of those original 2.4 kernels and wondering if the kernel version may be related to any problems they might be having are probably not going to see anything of benefit here. I didn't want to do an analysis on seventy different versions of the kernel, just the most recent."

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