Re: swap size for 2gb 2 processors?

ray wrote:
On Thu, 21 Dec 2006 04:58:21 -0900, Floyd L. Davidson wrote:

General Schvantzkoph <schvantzkoph@xxxxxxxxx> wrote:
On Thu, 21 Dec 2006 11:22:22 +0000, Ron Hardin wrote:

How big should I partition swap for 2gb ram 2 processors? Planning
out a partition magic run on a 120 gb disk, sharing with windows XP.

The rule of thumb is 2 * RAM size, in your case that would be 4G. This is
There is no such rule of thumb for Linux, and *never* has been.
Use Google and learn something about it before you post false
statements.


Do you know what a 'rule of thumb' is? In days past, there was indeed a
rule of thumb if not a hearty recommendation for swap = 2*physicalRAM.
This was in the day before 1gb was fairly common, but indeed, it was there.

The rule came from way back when swapping meant what it said. When a process
was sleeping and memory was needed, the entire process was copied to disk.
Disk space was allocated at process creation. So there had to be at least
enough disk space for all running processes to run the system at all. Now to
get any use from the swapping feature, there had to be more space than that,
so someone figured the 2x rule of thumb. 2 was probably chosen because if
you needed to swap more than that, you were in big trouble anyway due to
memory shortage. Trouble was, in those days, you could not add anymore
memory (typically 124 KBytes).

Current versions of UNIX and AFAIK all versions of Linux do not swap at all;
they page; i.e., they write out the least recently used pages in an attempt
to keep just the working set in memory. So if the old criterea applied, the
rule of thumb for Linux systems would be 1x the amount of memory for paging
disk space (still called swap space for historical reasons). But my
experience (and your guess is as good as mine if it is typical) is that the
more RAM you have, the less "swap space" you need and for the way I run, 8
GBytes (32-bit machine) is such that no paging has occurred in the last 61 days.

--
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