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Memory usage difference between task manager and free

asked 2012-01-06 14:37:11 -0500

Majid Azimi gravatar image

Hi guys,

I'm using fedora 16 XFCE with 2 gigabyte of ram. Task manager is showing that I'm using about 24% of memory. but when I issue free -m it shows that I'm using 1.3 GB of ram. here is the output:

             total       used       free     shared    buffers     cached
Mem:          2003       1332        671          0         14        825
-/+ buffers/cache:        491       1511
Swap:            0          0          0

I have removed all unnecessary services. But still can't reduce the initial memory usage to 500MB which I could do it with fedora 15. First why there is difference between task manager and free? Second why I am using this amount of memory whit no active services running?(I'm actually posting this with only firefox open.) Here is the output of ps -ax:

  PID TTY      STAT   TIME COMMAND
    1 ?        Ss     0:01 /sbin/init
    2 ?        S      0:00 [kthreadd]
    3 ?        S      0:01 [ksoftirqd/0]
    6 ?        S      0:00 [migration/0]
    7 ?        S      0:00 [watchdog/0]
    8 ?        S      0:00 [migration/1]
   10 ?        S      0:01 [ksoftirqd/1]
   12 ?        S      0:00 [watchdog/1]
   13 ?        S<     0:00 [cpuset]
   14 ?        S<     0:00 [khelper]
   15 ?        S      0:00 [kdevtmpfs]
   16 ?        S<     0:00 [netns]
   17 ?        S      0:00 [sync_supers]
   18 ?        S      0:00 [bdi-default]
   19 ?        S<     0:00 [kintegrityd]
   20 ?        S<     0:00 [kblockd]
   21 ?        S<     0:00 [ata_sff]
   22 ?        S      0:00 [khubd]
   23 ?        S<     0:00 [md]
   26 ?        S      0:07 [kswapd0]
   27 ?        SN     0:00 [ksmd]
   28 ?        SN     0:03 [khugepaged]
   29 ?        S      0:00 [fsnotify_mark]
   30 ?        S<     0:00 [crypto]
   36 ?        S<     0:00 [kthrotld]
   37 ?        S      0:00 [kworker/u:1]
   38 ?        S      0:00 [scsi_eh_0]
   39 ?        S      0:00 [scsi_eh_1]
   40 ?        S      0:00 [kworker/u:2]
   41 ?        S<     0:00 [kpsmoused]
  142 ?        S<     0:00 [ttm_swap]
  279 ?        S<     0:00 [firewire]
  366 ?        S      0:00 [jbd2/sda4-8]
  367 ?        S<     0:00 [ext4-dio-unwrit]
  405 ?        S      0:00 [kauditd]
  408 ?        Ss     0:00 /sbin/udevd
  415 ?        S      0:00 [flush-8:0]
  457 ?        Ss     0:00 /lib/systemd/systemd-stdout-syslog-bridge
  546 ?        S      0:00 /sbin/udevd
  556 ?        S      0:00 /sbin/udevd
  632 ?        S<     0:00 [rpciod]
  646 ?        S<     0:00 [hd-audio0]
  652 ?        S<     0:00 [hd-audio1]
  750 ?        Ss     0:00 /sbin/mount.ntfs /dev/sda6 /media/personel -o rw
  756 ?        Ss     0:15 /sbin/mount.ntfs /dev/sdb1 /media/very -o rw
  757 ?        S<     0:00 [ext4-dio-unwrit]
  761 ?        Ss     0:00 /sbin/mount.ntfs /dev/sda5 /media/software -o rw
  762 ?        Ss     0:00 /sbin/mount.ntfs /dev/sda1 /media/windows -o rw
  781 ?        Ss     0:00 avahi-daemon: running [linux.local]
  784 ?        S<sl   0:00 /sbin/auditd -n
  787 ?        Ssl    0:00 /usr/sbin/NetworkManager --no-daemon
  790 ?        Ss     0:00 /usr/sbin/abrtd -d -s
  791 ?        Ss     0:00 /usr/bin/abrt-dump-oops -rwxD /var/log/messages
  802 ?        Ss     0:00 /usr/sbin/atd -f
  803 ?        Ss     0:00 /usr/sbin/irqbalance
  804 ?        Ss     0:00 /lib/systemd/systemd-logind
  805 ?        S      0:00 avahi-daemon: chroot helper ...
(more)
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answered 2012-01-06 16:13:59 -0500

mooninite gravatar image

The first line of free includes cached memory usage. Cached memory includes opened files or programs that were loaded into memory at one point of time, but have been closed so the memory is not locked by them any longer. This is indicated by the "buffers" and "cached" column at the end of the first line. In order to find your true memory usage you should either subtract the "cached" and "buffers" column from "used" or just look at your second line that already subtracts the cached amount.

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Asked: 2012-01-06 14:37:11 -0500

Seen: 1,130 times

Last updated: Jan 06 '12