From: caadams@leo.unm.edu (Clifford A Adams)
Subject: Needed: a guide to setting up swap space.
Date: Sun, 12 Apr 92 05:39:14 GMT
Organization: University of New Mexico, Albuquerque
Summary: FAQ instructions on swap space are unclear and need additions.
Keywords: linux, swap, setup, installation, mkswap, swapon

	I recently installed Linux on my HD (/dev/hda1 mostly
following I Reid's instructions), and things seem to be running OK.  I
have 4 meg of ram (2.7meg reported free after buffers, etc), which is
enough for most activities.  However, I'd like to add a few meg of
swap space (especially since I like to use the full GNU Emacs while
simultaneously compiling with GCC. :-)  I have about 200k of various
FAQs and guides, but none of them explicitly say much about how to set
up swap space.  I don't think I've been successful so far in figuring
it out...

	Here are my problems (using 0.95c+ boot floppy and a mostly
0.95a root on /dev/hda1):

	* "mkswap" was on my 0.95a rootdisk.  There seems to be a
newer version (later file date) at tsx-11 under the binaries tree
(the later one is bigger).  What are the differences, and which should
I use?  For the rest of my experiments 

	* Looking at "mkswap" I noticed a "-c" option--what does it
do?  Early on I thought that "-c" meant "create", and that otherwise
mkswap would set up and use the swapfile.  At the moment it seems like
you use swapon to set up a swap file--at the first reading it seemed
like swapon was only for swap partitions...

	* I made a file "/dev/swapfile" using emacs to create a file
of 1K spaces, then using cat to make 4K/16K/64K/256K/1meg files, and finally
the 6 meg /dev/swapfile.  I didn't know if it would need a little more
space for tables or whatever so I added another 256K as extra.
		* Is there a better way to create the swapfile?
		* Do I need to have more space than the #blocks I tell mkswap?

	* I noticed that the mkswap blocks are 1K--this should
probably be noted since its different than the filesystem blocks...

	* Is there any way to tell how much swap space you are using or
have left?

...What I'd really like to see is a guide something like Reid's guide
to installation for setting up swap space--one that would cover both
swapfiles and swap partitions.  (Perhaps it could be added as an
appendix to the guide?).  Just a list of the commands and what they do
would be nice however...

	Finally, my first impression of Linux is: "zippy".  Its been a
long time since I've had the kind of quick response Linux gives, even
when I worked on "unloaded" machines (where I'm the only user, the load
avg is 0.00, etc...).  Even when running GNU emacs the response is
excellent (on my 40mhz 386 w/64K cache).  It may seem like a
small difference between the seeming immediate Linux response and the
more typical 2/3-1 second reaction time, but it feels nice...  (Its also
nice not to wait for overloaded NFS fileservers, and being able to
mess with the kernal is a plus. :-)

			--Cliff

-- 
Clifford A. Adams --- "Understanding is inasmuch as becoming."
caadams@triton.unm.edu | 457 Ash St. NE/Albuquerque, NM 87106 | (505) 242-4519
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