[RndTbl] Kernel 2.6 Swappiness
Jeff Green
jmgreen7 at mts.net
Thu May 13 08:41:30 CDT 2004
Just a little heads up about something that kernel 2.6 users may not have
noticed. When I installed the 2.6.5 kernel I was poking around '/proc' and
noticed a file in '/proc/vm' called 'swappiness' (which had a value of 60). I
had some idea about what it was for but there was no mention of it in the
kernel docs. Later that day I was looking at http://kerneltrap.org and
noticied this article:
http://kerneltrap.org/node/view/3000?PHPSESSID=d5c5223a98199bf350e69d77c36ca785
It says 'swappiness' can be set between 0 and 100 (0 = no swapping, 100 =
lotsa swapping) and mentions some recent discussions on the kernel mailing
list about what 'swappiness' setting is ideal (i.e., don't swap anything to
disk or swap everything to disk or some middle ground). The kernel
maintainer, Andrew Morton, sets it 100 to free up as much memory as possible,
while others think that desktop users don't want a delay when switching back
to their apps so 'swappiness' should be closer to 0. I have it set at 25 now
and it seems to work well (with 320 MB RAM) for everyday desktop use.
Just for completeness, if you want to set the 'swappiness' value use:
sysctl -w vm.swappiness=x [ 'x' being a value from 0-100 ]
And put:
vm.swappiness=x
in '/etc/sysclt.conf' (or wherever 'sysctl.conf' is on you machine) to keep
that value on reboot.
That's all for now.
Jeff Green
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