02-10-2012
You are having the standard Linux Newbie Memory Freakout. Cache memory counts as free memory.
Linux uses every spare bit of memory to cache all disk accesses, because memory which sits around doing nothing is useless. But cache will be recycled for other uses as needed. It's only sitting around as cache right now because it's not needed. Large amounts of cache are to be expected on an unloaded and idle system.
You want to have at least some cache, anyway. If you use so much memory that there's nothing left for cache, this is a problem -- disk access will become slow. The more cache you have, the more efficient disk access can become.
Do not, repeat, do not reboot your system, plug weird values into /proc/ to "flush the cache", and so forth. Everything is fine.
Last edited by Corona688; 02-10-2012 at 11:45 AM..
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CFS(4) Kernel Interfaces Manual CFS(4)
NAME
cfs - cache file system
SYNOPSIS
cfs -s [-rd] [-f partition]
cfs -a netaddr [-rd] [-f partition] [mtpt]
DESCRIPTION
Cfs is a user-level file server that caches information about remote files onto a local disk. It is normally started by the kernel at boot
time, though users may start it manually. Cfs is interposed between the kernel and a network connection to a remote file server to improve
the efficiency of access across slow network connections such as modem lines. On each open of a file cfs checks the consistency of cached
information and discards any old information for that file.
Cfs mounts onto mtpt (default /) after connecting to the file server.
The options are:
s the connection to the remote file server is on file descriptors 0 and 1.
a netaddr
dial the destination netaddr to connect to a remote file server.
r reformat the cache disk partition.
d turn on debugging
f partition
use file partition as the cache disk partition.
All 9P messages except read, clone, and walk (see intro(5)) are passed through cfs unchanged to the remote server. A clone followed imme-
diately by a walk is converted into a clwalk. If possible, a read is satisfied by cached data. Otherwise, the file server is queried for
any missing data.
FILES
/dev/hd0cache
Default file used for storing cached data.
SOURCE
/sys/src/cmd/cfs
CFS(4)