dynamic swap prioritizing

[Xuan Baldauf <xuan--lkml@baldauf.org>]

Hello,

I have a linux box with 3 harddisks of different
characteristics (size, seek time, throughput), each capable
of holding a swap partition. Sometimes, one harddisk is
driven heavily (e.g. database application), sometimes, the
other harddisk is busy.

I imagine following optimization:
- all swap partitions have the same priority from the start
on
- runtime statistics are gathered covering response time
(time from page request to availability)
- the fastest drive is used first (or maybe in striping mode
parallely woth the second-fastest drive)
- because the fastest drive will be more busy, its response
times will rise, reaching equality with other drives
- at that point, other drives are also considered for
swapout
- that system regularily adapts its decisions based on
recent statistics ("recent" is a tuning parameter)

Such an algorithm also would properly prioritize
network-swap and video-memory-swap, reducing time and cost
of a manual priority configuration (and statistics
gathering).

Does the linux kernel already implement such an
optimization? Is it planned?

Xuân.