new memory = more swap?

[Kent Borg]

On Thu, Mar 25, 2004 at 02:21:24PM -0500, duncan brown wrote:
> well, yes and no.  the old '2 x memory = swapsize' addage is sort of
> outdated.

My suggestion, if you have a reasonably modern machine and have enough
disk space, is to use 1 GB of swap.  Period.

Current Linux kernels, and current disk and bus speeds, just seem to
fit 1 GB.  With a little RAM it is possible to use a good chunk of
that without being unusably slow.  On machines with tons of RAM,
having a "little" swap--an amount that is well less than your
RAM--seems cheap and harmless insurance.  On in between machines I
have seen the kernel use swap even when there seemed no particular
reason.  It seems to like swap.

Having less than 1 GB doesn't save much, and having more is hard to
imagine using.

An exception: if you have a specific data set that is X-big, then
certainly make your swap plus RAM big enough to easily handle X-bytes
with some extra slop.  Also make sure your RAM holds your working set.

Another exception: if you have a lot of RAM and are afraid of
swap-based delays, experiment with using no swap.  You might get the
more predictable behavior of things either working or pretty much not
working, without a long, drawn out degradation path.  It is a simpler
case, and whether it is useful depends upon your needs; I doubt this
is a very common case.

Otherwise, for the moment, 1 GB seems pretty nice.


-kb, the Kent who wants his computer to degrade gradually instead of
suddenly refusing to do things, but that isn't for everybody in all
circumstances.