[CentOS] Where is cached memory going?

ABBAS KHAN bashukhan at gmail.com
Tue Aug 19 16:31:17 UTC 2008

As by the time, I've learned that Linux works by caching apps by using a lot
of RAM and then it reallocates the new stuff by cleaning the old cached
pages from memory as compared to other OSs. With 2 gigs of RAM often I see
the free memory only as 100-400MB. Using TOP or PS, it doesn't look like any
program or process is using excessive memory (the highest process is seen
with 1-2% total memory). *So, my questions are:*

 what programs are using that much of memory? (or cached memory)
Is that really due to a lot of cache in the memory
*if yes, then, is there a way to parse the cache to findout what
applications are eating up the cache?*
*how to free the cached memory?*

*Currently, here are the details:*

Top two high mem processes only using 2.6% of RAM.

[root at Ether ~]# ps aux | sort -nrk4 | head -2
abbask    5922  0.0  1.4 364300 28312 ?        S    Aug19   0:00
/usr/bin/python -E /usr/bin/sealert -s
ntop      4914  0.0  1.2 332752 24760 ?        Ssl  Aug19   0:00 ntop -d -L

[root at Ether ~]# head -5 /proc/meminfo
MemTotal:      1913856 kB
MemFree:        500612 kB
Buffers:        169720 kB
Cached:         751000 kB
SwapCached:          0 kB

[root at Ether ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1869       1380        488          0        165        733
-/+ buffers/cache:        480       1388
Swap:         1983          0       1983

*Total percentage memory for all the processes, being used is 15.5% only.

*[root at Ether ~]# ps aux | awk '{print $4}' | grep [0-9] | tr -s "\n" "+" |
awk '{print $1 0 }' | bc

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