Tuning for very little RAM

Bruce Cran bruce at cran.org.uk
Wed Jan 6 15:52:41 UTC 2010

On Tue, 05 Jan 2010 20:03:45 +1000
Da Rock <freebsd-questions at herveybayaustralia.com.au> wrote:

> Its been a while- work's has been keeping me very busy for months now.
> I have revived an old laptop which has very little RAM, and it is
> absolutely hammering the swap.
> I'm trying to set it up as a demo for some skeptics with no money, so
> I need email, internet (with plugins), openoffice, acrobat, and wine.
> Aside from all that though, for the academics of it how can I help
> this situation? The laptop has around 100MB RAM, with 16k free, and
> has a new install of FreeBSD 8.0.

You can save a bit of memory by building a custom kernel. First, remove
any options you don't need such as INET6, NFS, AUDIT etc. Then, you can
replace "device ata" with more specific drivers, and "device mii" with
specific PHY drivers for your NIC. On a 128MB box I have that's running
8-STABLE my kernel is just 4.1MB.

You should also be able to build Xorg so it'll use less memory - for
example by not requiring hald but getting it to read the
configuration from xorg.conf instead.

You can also tell FreeBSD to agressively swap idle processes out by
setting vm.swap_idle_enabled to 1.

Bruce Cran

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