Memory Usage

[7280]

Hi,
I have two linux box on which websphere is running.
Both servers has 16gb ram and I see a lot of memory used (about 10gb) but I'm not understanding why since websphere uses about 2gb.

[root@prdlxwas1 ~]# free
total used free shared buffers cached
Mem: 16410656 13096904 3313752 0 956524 8337172
-/+ buffers/cache: 3803208 12607448
Swap: 8388600 0 8388600
[root@prdlxwas1 ~]# cat /proc/meminfo
MemTotal: 16410656 kB
MemFree: 3313752 kB
Buffers: 956524 kB
Cached: 8337172 kB
SwapCached: 0 kB
Active: 9057096 kB
Inactive: 2669756 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 16410656 kB
LowFree: 3313752 kB
SwapTotal: 8388600 kB
SwapFree: 8388600 kB
Dirty: 184 kB
Writeback: 0 kB
Mapped: 2477516 kB
Slab: 1330344 kB
CommitLimit: 16593928 kB
Committed_AS: 2726372 kB
PageTables: 8792 kB
VmallocTotal: 536870911 kB
VmallocUsed: 266920 kB
VmallocChunk: 536603959 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 2048 kB

[root@prdlxwas1 ~]# ps h -e -o %mem,%cpu,pid,user,state,start,time,etime,comm | sort -rn | head -n 6
4.9 7.7 26874 root S May 22 13:06:27 7-01:19:44 java
4.5 3.5 8150 root S 08:12:21 00:03:43 01:45:49 java
1.8 0.2 12804 root S May 24 00:18:19 4-17:53:34 java
1.7 0.3 28512 root S 15:55:20 00:04:01 18:02:50 java
1.7 0.1 20362 root S May 07 01:01:16 21-15:01:38 java
1.3 0.2 12707 root S May 24 00:14:29 4-17:54:23
java

Following is output of ps aux of one process:
[root@prdlxwas1 ~]# ps aux | grep 26874 | grep -v grep
root 26874 7.7 4.9 2031308 809484 ? Sl May22 786:32 /opt/WebSphere61/AppServer/java/bin/java

I want to understand why I see 13gb used. And are these really used? If yes, who is using them?

Thanks in advance.

 

[GunnarD]

*nix system is design to use free memory for cacheing, and when a program needs memory this memory is taking from memory i cachepool.

So it is normal that a *nix system has "litlle free" memory.

 

[7280]

How can I see "real" used memory?

Thanks again.

 

[thedaver]

-/+ buffers/cache: 3803208 12607448

You have ~4GB committed to programs/kernel/data

You have ~12GB free AND/OR used by cache - which is also considered free since programs and program data may use it.

D.E.R. Management - IT Project Management Consulting

http://www.dermanagement.com/