On Monday 09 July 2001 08:10, you wrote:
> Would the amount of swap in use be a good benchmark to judge whether
> your system would benefit from more RAM? I mean, if in normal use you
> don't use any swap, then you have a very sufficient amount of RAM.
Not necessarily. I have, for example, 256 megs of RAM, but often I find stuff
in swap, maybe up to 50 megs or so. Under normal conditions I don't feel the
need for having more RAM at present. Still, every time I've gotten new
hardware or upgraded, I've always ended up getting more RAM all the time :).
As a side issue: the original poster should get as much RAM as he can afford,
without necessarily "going overboard". For my purposes, I bought 256, which I
thought should be enough for what I do. Hopefully, I won't have to add more,
but like everything else, will probably have to add more sometime down the
road.
Now back to the main point. Most systems run any number of deamon or other
processes all the time. Most of these don't get a whole lot of use, but they
still need memory, even if they are sleeping. Now, upon boot, you find that
none of your swap is used, which is a good thing, otherwise your system is
swapping during boot :). You start X and KDE ( or whatever) and that uses a
little more. Still, no additions to swap, so far so good.
Now comes along a need for a large amount of RAM. It could be Netscape
growing leaps and bounds, or it could be a large compile, or whatever else.
Suddenly, the system needs some additional memory, so it starts swapping some
stuff -- and some of that are parts of those sleeping daemons I wrote about
earlier. After a time you finish needing all that memory, but still you show
some swap - and those are parts of programs that were swapped out earlier, of
course. Inasmuch as some portions of that are parts of sleeping deamons, tnat
part of swap may stay in swap indefinitely, without any harm to the system,
and this in fact frees up more memory in case you need to do another thing
that requires a large amount of memory. And the system won't suddenly swap in
parts of programs even if there be room for them after you've closed down an
application -- it would be wasteful of resources to bring back parts of
sleeping processes, for instance. The memory is better served for other
things.
Only if you continually run things that cause excessive swapping do you
really need to upgrade your memory. But adding more memory is usually one
place where you can make your system faster and more responsive.
> My system (with 128 MB of RAM) usually starts out using no swap but then
> starts using more and more swap as time goes by (and as I use more /
> different applications).
That's par for the course. 128 might just be enough for you. The key I think
is more (and different) applications. When you load an app, the os needs to
find a place for it, obviously, and this might mean a couple of things --
that some stuff needs to be swapped out, in anticicipation of needing more
memory, and that your buffers / free / cache memory will get smaller because
the new app now needs part of these resources. And i fyou are using different
applications more and more, there is going to be less common things that can
remain in memory.
--
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David E. Fox Thanks for letting me
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