1999 Linux Symposium

memory management part 1


Too little, too slow; changing memory management

Rik van Riel, Conectiva

Computers have changed over the years, the memory hierarchy now has completely different dimensions than it had just a few years ago. In the time that CPUs have gotten a factor 100 faster, memory has just become 10 times as large and 20 times as fast. Harddisks lag even more. This has changed memory management into something completely different than what's in the textbooks.

On one side, memory management has turned into micro management and hiding MM tricks in other kernel code (page colouring, better scheduling techniques, etc). On the other side we have to do our I/O in bulk and take a lot of overhead just to get some efficiency in our handling of the hardware. Optimising it will cost even more effort.

In this lecture I plan on showing some of the (sometimes strange) optimisations that were done to increase system performance. Some of these changes will be well-known to the audience but never recognised as being memory management (and never viewed from the MM angle). Other changes will be in memory management code itself but may still be counterintuitive for people familiar with the memory management from the textbooks.

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