Comments?
There are several files in /proc/sys/vm you can use to tune the
memory system with.
You can look at them with cat, and set them by echo, for example:
echo 128 256 512 > /proc/sys/vm/freepages
/proc/sys/vm/freepages:
This contains three consecurive numbers: min_free_pages, free_pages_low
and free_pages_high.
Free memory never goes down below min_free_pages except for atomic
allocation. Background swapping is started if the number of free
pages falls below free_pages_high, and intensive swapping is started
below free_pages_low. A "page" is 4 kB.
If "out of memory" errors sometimes occur, or if your machine does lots
of networking, increasing min_free_pages to 64 or more may be a good
idea.
free_pages_low should probably be about double of min_free_pages.
After a period of inactivity, the difference between free_pages_high and
free_pages low is immediately available for any program you want to
start up, without any need to swap out anything else. If your memory
is large enough (e.g. > 16 Meg), keeping 2 or 3 megabytes of memory
ready for anything that might start up is probably a good idea.
I've found that
echo 128 256 1024 > /proc/sys/vm/freepages
gives good performance for a 32 Meg system used as a small server and
personal workstation.
The other two files in /proc/sys/vm are undocumented, as yet.
-- Thomas Koenig, Thomas.Koenig@ciw.uni-karlsruhe.de, ig25@dkauni2.bitnet. The joy of engineering is to find a straight line on a double logarithmic diagram.