Xubuntu Saucy with 4GB RAM. When the computer is restarted and immediately after login, about 500 MB of RAM is taken according to free -m. Then I run some programs and memory usage goes above 3 GM.
Now here is the problem: If I close all the open applications, still about 2.5 GB of memory is used but no thread accounts for all this memory. Here is the result of ps aux:
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 27092 2680 ? Ss mar27 0:02 /sbin/init
root 2 0.0 0.0 0 0 ? S mar27 0:00 [kthreadd]
root 3 0.0 0.0 0 0 ? S mar27 0:25 [ksoftirqd/0]
root 5 0.0 0.0 0 0 ? S< mar27 0:00 [kworker/0:0H]
root 7 0.0 0.0 0 0 ? S mar27 0:15 [migration/0]
root 8 0.0 0.0 0 0 ? S mar27 0:00 [rcu_bh]
root 9 0.0 0.0 0 0 ? S mar27 0:00 [rcuob/0]
root 10 0.0 0.0 0 0 ? S mar27 0:00 [rcuob/1]
root 11 0.0 0.0 0 0 ? S mar27 0:24 [rcu_sched]
root 12 0.0 0.0 0 0 ? S mar27 0:11 [rcuos/0]
root 13 0.0 0.0 0 0 ? S mar27 0:12 [rcuos/1]
root 14 0.0 0.0 0 0 ? S mar27 0:01 [watchdog/0]
root 15 0.0 0.0 0 0 ? S mar27 0:01 [watchdog/1]
root 16 0.0 0.0 0 0 ? S mar27 0:11 [migration/1]
root 17 0.0 0.0 0 0 ? S mar27 0:22 [ksoftirqd/1]
root 19 0.0 0.0 0 0 ? S< mar27 0:00 [kworker/1:0H]
root 20 0.0 0.0 0 0 ? S< mar27 0:00 [khelper]
root 21 0.0 0.0 0 0 ? S mar27 0:00 [kdevtmpfs]
root 22 0.0 0.0 0 0 ? S< mar27 0:00 [netns]
root 23 0.0 0.0 0 0 ? S< mar27 0:00 [writeback]
root 24 0.0 0.0 0 0 ? S< mar27 0:00 [kintegrityd]
root 25 0.0 0.0 0 0 ? S< mar27 0:00 [bioset]
root 27 0.0 0.0 0 0 ? S< mar27 0:00 [kblockd]
root 29 0.0 0.0 0 0 ? S< mar27 0:00 [ata_sff]
root 30 0.0 0.0 0 0 ? S mar27 0:00 [khubd]
root 31 0.0 0.0 0 0 ? S< mar27 0:00 [md]
root 32 0.0 0.0 0 0 ? S< mar27 0:00 [devfreq_wq]
root 35 0.0 0.0 0 0 ? S mar27 0:00 [khungtaskd]
root 36 0.0 0.0 0 0 ? S mar27 0:05 [kswapd0]
root 37 0.0 0.0 0 0 ? SN mar27 0:00 [ksmd]
root 38 0.0 0.0 0 0 ? SN mar27 0:00 [khugepaged]
root 39 0.0 0.0 0 0 ? S mar27 0:00 [fsnotify_mark]
root 40 0.0 0.0 0 0 ? S mar27 0:00 [ecryptfs-kthrea]
root 41 0.0 0.0 0 0 ? S< mar27 0:00 [crypto]
root 53 0.0 0.0 0 0 ? S< mar27 0:00 [kthrotld]
root 74 0.0 0.0 0 0 ? S< mar27 0:00 [deferwq]
root 75 0.0 0.0 0 0 ? S< mar27 0:00 [charger_manager]
root 122 0.0 0.0 0 0 ? S< mar27 0:00 [firewire]
root 124 0.0 0.0 0 0 ? S mar27 0:00 [scsi_eh_0]
root 125 0.0 0.0 0 0 ? S mar27 0:00 [scsi_eh_1]
root 126 0.0 0.0 0 0 ? S mar27 0:00 [scsi_eh_2]
root 127 0.0 0.0 0 0 ? S mar27 0:00 [scsi_eh_3]
root 144 0.0 0.0 0 0 ? S mar27 0:03 [jbd2/sda6-8]
root 145 0.0 0.0 0 0 ? S< mar27 0:00 [ext4-rsv-conver]
root 146 0.0 0.0 0 0 ? S< mar27 0:00 [ext4-unrsv-conv]
root 346 0.0 0.0 0 0 ? S< mar27 0:00 [cfg80211]
root 347 0.0 0.0 0 0 ? S< mar27 0:00 [kpsmoused]
root 392 0.0 0.0 0 0 ? S< mar27 0:00 [hd-audio0]
102 531 0.0 0.0 31640 2500 ? Ss mar27 0:13 dbus-daemon --system --fork
root 590 0.0 0.0 37140 1580 ? Ss mar27 0:00 /lib/systemd/systemd-logind
root 591 0.0 0.0 83484 3324 ? Ss mar27 0:02 /usr/sbin/modem-manager
root 592 0.0 0.0 19396 2116 ? Ss mar27 0:00 /usr/sbin/bluetoothd
root 625 0.0 0.0 0 0 ? S< mar27 0:00 [krfcommd]
root 636 0.0 0.1 271524 5588 ? Ssl mar27 0:21 NetworkManager
root 659 0.0 0.1 284248 5392 ? Sl mar27 0:03 /usr/lib/policykit-1/polkitd --no-debug
syslog 692 0.0 0.0 247476 1304 ? Sl mar27 0:19 rsyslogd -c5
root 797 0.0 0.0 16056 548 ? S mar27 0:00 upstart-socket-bridge --daemon
root 800 0.0 0.0 15668 516 ? S mar27 0:00 upstart-file-bridge --daemon
root 851 0.0 0.0 24236 748 tty4 Ss+ mar27 0:00 /sbin/getty -8 38400 tty4
root 854 0.0 0.0 24236 748 tty5 Ss+ mar27 0:00 /sbin/getty -8 38400 tty5
root 860 0.0 0.0 24236 748 tty2 Ss+ mar27 0:00 /sbin/getty -8 38400 tty2
root 863 0.0 0.0 24236 748 tty3 Ss+ mar27 0:00 /sbin/getty -8 38400 tty3
root 872 0.0 0.0 24236 748 tty6 Ss+ mar27 0:00 /sbin/getty -8 38400 tty6
root 932 0.0 0.0 4376 612 ? Ss mar27 0:00 acpid -c /etc/acpi/events -s /var/run/acpid.socket
root 933 0.0 0.0 25804 900 ? Ss mar27 0:00 cron
root 951 0.0 0.0 275628 3052 ? SLsl mar27 0:00 lightdm
root 994 1.4 2.7 300936 113208 tty7 Ss+ mar27 112:27 /usr/bin/X -core :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
root 997 0.0 0.0 24236 752 tty1 Ss+ mar27 0:00 /sbin/getty -8 38400 tty1
root 1021 0.0 0.0 279004 4008 ? Sl mar27 0:06 /usr/lib/accountsservice/accounts-daemon
root 1035 0.0 0.0 0 0 ? S mar27 0:00 [kauditd]
root 1085 0.0 0.0 163808 2988 ? Sl mar27 0:00 lightdm --session-child 12 19
root 1094 0.0 0.0 32692 2836 ? Ss mar27 0:11 /sbin/wpa_supplicant -B -P /run/sendsigs.omit.d/wpasupplicant.pid -u -s -O /var/run/wpa_supplicant
rez 1144 0.0 0.0 37560 1848 ? Ss mar27 0:01 init --user
rez 1195 0.0 0.0 12624 92 ? Ss mar27 0:00 ssh-agent
rez 1200 0.0 0.0 32716 2572 ? Ss mar27 0:08 dbus-daemon --fork --session --address=unix:abstract=/tmp/dbus-S88cKKbWgL
rez 1205 0.0 0.0 26516 1044 ? Ss mar27 0:00 upstart-event-bridge
rez 1216 0.0 0.0 4440 576 ? Ss mar27 0:00 /bin/sh /etc/xdg/xfce4/xinitrc -- /etc/X11/xinit/xserverrc
rez 1224 0.0 0.2 328460 11808 ? Sl mar27 0:11 xfce4-session
rez 1229 0.0 0.0 34996 760 ? S mar27 0:00 upstart-file-bridge --daemon --user
rez 1230 0.0 0.0 26520 528 ? S mar27 0:01 upstart-dbus-bridge --daemon --session --user --bus-name session
rez 1232 0.0 0.0 26520 532 ? S mar27 0:01 upstart-dbus-bridge --daemon --system --user --bus-name system
rez 1235 0.0 0.0 39360 2432 ? S mar27 0:00 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd
rez 1238 0.0 0.4 320204 16784 ? Sl mar27 3:51 xfwm4 --replace --display :0.0 --sm-client-id 273d07c4e-c10c-41ee-8cf9-2374cb32777e
rez 1240 0.0 1.2 1151052 50204 ? Sl mar27 2:10 Thunar --sm-client-id 20caa2dc4-4174-44d3-82ef-fbb67bffe778 --daemon
nobody 1242 0.0 0.0 39412 1340 ? S mar27 0:01 /usr/sbin/dnsmasq --no-resolv --keep-in-foreground --no-hosts --bind-interfaces --pid-file=/var/run/NetworkManager/dnsmasq.pid --listen-address=127.0.1.1 --conf-file=/var/run/NetworkManager/dnsmasq.conf --cache-size=0 --proxy-dnssec --enable-dbus=org.freedesktop.NetworkManager.dnsmasq --conf-dir=/etc/NetworkManager/dnsmasq.d
rez 1266 0.0 0.7 526112 31824 ? Sl mar27 0:19 xfdesktop --display :0.0 --sm-client-id 2da06fe80-f4ae-4839-8b3b-91600fe2eb68
rez 1267 0.0 0.6 348032 24372 ? Ssl mar27 0:20 xfsettingsd --display :0.0 --sm-client-id 2ba6a0c3b-f588-4771-9570-4b877c7f8c7f
rez 1300 0.0 0.0 200876 2908 ? Sl mar27 0:00 /usr/lib/gvfs/gvfsd
rez 1304 0.0 0.0 336860 2484 ? Sl mar27 0:00 /usr/lib/gvfs//gvfsd-fuse -f /run/user/1000/gvfs
rez 1322 0.0 0.3 311836 12852 ? Ssl mar27 0:07 xfce4-power-manager --restart --sm-client-id 2ad69ea99-5f8a-4c94-afef-b10023557baf
rez 1324 0.0 0.3 453000 15768 ? Sl mar27 0:01 /usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1
rez 1334 0.0 0.0 337356 2724 ? Sl mar27 0:00 /usr/lib/at-spi2-core/at-spi-bus-launcher
rez 1340 0.0 0.0 30488 1612 ? S mar27 0:00 /bin/dbus-daemon --config-file=/etc/at-spi2/accessibility.conf --nofork --print-address 3
rez 1344 0.0 0.0 124920 2956 ? Sl mar27 0:01 /usr/lib/at-spi2-core/at-spi2-registryd --use-gnome-session
rez 1347 0.0 0.7 958552 29336 ? SLl mar27 1:28 nm-applet
rez 1352 0.0 0.9 344436 39920 ? Ssl mar27 0:25 xfce4-volumed
rez 1355 0.0 0.0 368400 3804 ? Sl mar27 0:06 /usr/lib/x86_64-linux-gnu/indicator-application-service
rez 1363 0.0 0.0 74664 2804 ? S mar27 0:21 xscreensaver -no-splash
rez 1372 0.6 0.1 365508 5072 ? Sl mar27 49:29 /usr/bin/pulseaudio --start --log-target=syslog
rtkit 1374 0.0 0.0 168920 1176 ? SNl mar27 0:02 /usr/lib/rtkit/rtkit-daemon
root 1399 0.0 0.1 298576 4396 ? Sl mar27 0:07 /usr/lib/upower/upowerd
rez 1497 0.0 0.1 450192 5196 ? Sl mar27 0:02 /usr/lib/gvfs/gvfs-udisks2-volume-monitor
root 1500 0.0 0.1 436580 5668 ? Sl mar27 0:30 /usr/lib/udisks2/udisksd --no-debug
rez 1536 0.0 0.0 200212 3276 ? Sl mar27 0:00 /usr/lib/gvfs/gvfs-mtp-volume-monitor
rez 1624 0.0 0.0 289908 2892 ? Sl mar27 0:00 /usr/lib/gvfs/gvfs-afc-volume-monitor
rez 1637 0.0 0.0 207980 2776 ? Sl mar27 0:00 /usr/lib/gvfs/gvfs-gphoto2-volume-monitor
rez 1639 0.0 0.0 61360 2336 ? S mar27 0:00 /usr/lib/x86_64-linux-gnu/gconf/gconfd-2
rez 1655 0.0 0.0 64324 2628 ? S mar27 0:01 /usr/bin/obex-data-server --no-daemon
rez 1832 0.0 0.3 476124 15004 ? Ssl mar27 0:05 xfrun4
rez 1943 0.0 0.7 450508 28392 ? Sl mar27 0:15 /usr/lib/gvfs/gvfsd-trash --spawner :1.9 /org/gtk/gvfs/exec_spaw/0
root 1997 0.0 0.0 24444 596 ? S mar27 0:00 dbus-launch --autolaunch=42613f7aae1f969ac75e6e7252f27376 --binary-syntax --close-stderr
root 1998 0.0 0.0 30652 1188 ? Ss mar27 0:00 //bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session
rez 2942 0.0 0.0 302736 3708 ? Sl mar27 0:00 /usr/lib/gvfs/gvfsd-http --spawner :1.9 /org/gtk/gvfs/exec_spaw/1
root 4058 0.0 0.0 39204 2312 ? S 13:54 0:00 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd
root 4067 0.0 0.0 200752 2952 ? Sl 13:54 0:00 /usr/lib/gvfs/gvfsd
root 4071 0.0 0.0 271324 3000 ? Sl 13:54 0:00 /usr/lib/gvfs//gvfsd-fuse -f /root/.gvfs
root 4443 0.0 0.1 515556 5524 ? Sl 13:54 0:00 /usr/lib/gvfs/gvfs-udisks2-volume-monitor
root 4451 0.0 0.0 200344 3384 ? Sl 13:54 0:00 /usr/lib/gvfs/gvfs-mtp-volume-monitor
root 4455 0.0 0.0 289908 3296 ? Sl 13:54 0:00 /usr/lib/gvfs/gvfs-afc-volume-monitor
root 4460 0.0 0.0 207980 3344 ? Sl 13:54 0:00 /usr/lib/gvfs/gvfs-gphoto2-volume-monitor
root 5845 0.0 0.0 17320 632 ? S 14:20 0:00 upstart-udev-bridge --daemon
root 5848 0.0 0.0 42964 1952 ? Ss 14:20 0:00 /lib/systemd/systemd-udevd --daemon
root 7073 0.0 0.0 128452 2276 ? Ss mar27 0:01 smbd -F
root 7076 0.0 0.0 129096 1124 ? S mar27 0:00 smbd -F
root 7112 0.0 0.0 91400 1348 ? Ss mar27 0:16 nmbd -D
root 9236 0.0 0.0 25248 1396 ? Ss mar30 0:03 hostapd -B /etc/hostapd-hotspot.conf -f /tmp/hostapd.log
root 10401 0.0 0.0 25248 1368 ? Ss mar30 0:04 hostapd -B /etc/hostapd-hotspot.conf -f /tmp/hostapd.log
rez 12137 0.0 0.1 125468 4216 ? Sl mar27 0:02 /usr/lib/gvfs/gvfsd-metadata
root 12267 0.0 0.0 0 0 ? S 14:42 0:00 [kworker/1:3]
rez 12435 0.0 0.0 178216 2648 ? Sl mar27 0:00 /usr/lib/dconf/dconf-service
root 13050 0.0 0.0 0 0 ? S< 14:44 0:00 [hci0]
root 13051 0.0 0.0 0 0 ? S< 14:44 0:00 [hci0]
dnsmasq 13805 0.0 0.0 39416 1028 ? S 15:24 0:00 /usr/sbin/dnsmasq -x /var/run/dnsmasq/dnsmasq.pid -u dnsmasq -r /var/run/dnsmasq/resolv.conf -7 /etc/dnsmasq.d,.dpkg-dist,.dpkg-old,.dpkg-new
root 13873 0.0 0.0 0 0 ? S 15:24 0:07 [irq/18-b43]
root 13875 0.0 0.0 25248 1344 ? Ss 15:24 0:01 hostapd -B /etc/hostapd-hotspot.conf -f /tmp/hostapd.log
root 13884 0.0 0.0 20944 988 ? S 15:24 0:02 /bin/bash /usr/bin/ap-hotspot start
rez 14672 0.0 0.1 684664 6128 ? Sl mar27 0:01 /usr/lib/indicator-sound-gtk2/indicator-sound-service
root 15097 0.0 0.0 195828 3936 ? Sl mar27 0:03 /usr/lib/udisks/udisks-daemon
root 15098 0.0 0.0 47844 528 ? S mar27 0:00 udisks-daemon: not polling any devices
rez 15264 0.0 0.0 374624 3600 ? SLl mar27 0:00 /usr/bin/gnome-keyring-daemon --start --foreground --components=secrets
root 15913 0.0 0.0 0 0 ? S 16:17 0:04 [kworker/0:2]
root 16432 0.0 0.0 0 0 ? S< mar27 0:00 [kworker/1:1H]
root 16733 0.0 0.0 0 0 ? S 16:37 0:00 [kworker/u4:0]
rez 16991 0.0 0.7 544484 30484 ? Sl mar30 0:00 /usr/bin/python /usr/bin/blueman-applet
root 17133 0.0 0.0 10244 3736 ? S 16:46 0:00 /sbin/dhclient -d -sf /usr/lib/NetworkManager/nm-dhcp-client.action -pf /run/sendsigs.omit.d/network-manager.dhclient-eth0.pid -lf /var/lib/NetworkManager/dhclient-1d839b90-39a2-4362-9cb0-0cba8724ef39-eth0.lease -cf /var/lib/NetworkManager/dhclient-eth0.conf eth0
root 17918 0.0 0.0 72940 2636 ? Ss mar27 0:00 /usr/sbin/cups-browsed
rez 18213 0.0 0.5 462292 22604 ? Sl mar27 0:01 artha
root 18672 0.0 0.0 25248 1356 ? Ss mar27 0:03 hostapd -B /etc/hostapd-hotspot.conf -f /tmp/hostapd.log
rez 18679 0.0 0.0 24444 596 ? S mar27 0:00 dbus-launch --autolaunch=42613f7aae1f969ac75e6e7252f27376 --binary-syntax --close-stderr
rez 18680 0.0 0.0 30524 1128 ? Ss mar27 0:00 //bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session
rez 18685 0.0 0.0 39232 2208 ? S mar27 0:00 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd
rez 18688 0.0 0.0 200752 2856 ? Sl mar27 0:00 /usr/lib/gvfs/gvfsd
root 19329 0.0 0.0 0 0 ? S 17:35 0:00 [kworker/0:1]
root 19677 0.0 0.0 0 0 ? S mar30 0:00 [jbd2/sda1-8]
root 19678 0.0 0.0 0 0 ? S< mar30 0:00 [ext4-rsv-conver]
root 19679 0.0 0.0 0 0 ? S< mar30 0:00 [ext4-unrsv-conv]
root 19967 0.0 0.0 0 0 ? S 17:52 0:00 [kworker/u4:1]
root 19996 0.0 0.0 61356 2576 ? S mar30 0:00 /usr/lib/x86_64-linux-gnu/gconf/gconfd-2
root 20457 0.0 0.0 0 0 ? S 18:03 0:00 [kworker/u4:2]
root 20532 0.0 0.0 25248 1396 ? Ss mar31 0:03 hostapd -B /etc/hostapd-hotspot.conf -f /tmp/hostapd.log
rez 20659 1.3 0.3 456460 15952 ? Sl 18:07 0:00 xfce4-terminal
rez 20663 0.0 0.0 14832 816 ? S 18:07 0:00 gnome-pty-helper
rez 20664 0.1 0.0 30540 3372 pts/5 Ss 18:07 0:00 bash
root 20727 0.0 0.0 15612 624 ? S 18:07 0:00 sleep 5
root 20728 0.6 0.0 69172 2292 pts/5 S+ 18:07 0:00 sudo ps aux
root 20729 0.0 0.0 26856 1348 pts/5 R+ 18:08 0:00 ps aux
root 22673 0.0 0.0 74436 2912 ? Ss mar28 0:00 /usr/sbin/cupsd -F
root 22880 0.0 0.0 25248 1372 ? Ss mar28 0:03 hostapd -B /etc/hostapd-hotspot.conf -f /tmp/hostapd.log
root 26957 0.0 0.0 0 0 ? S< mar31 0:00 [kworker/u5:2]
rez 28053 0.0 0.5 440980 22640 ? Sl mar30 1:41 xfce4-panel
rez 28057 0.0 0.2 168856 10340 ? S mar30 0:00 /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper /usr/lib/x86_64-linux-gnu/xfce4/panel/plugins/libactions.so 9 14680107 actions Action Buttons Log out, lock or other system actions
rez 28059 0.0 0.1 158580 7540 ? S mar30 0:00 /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper /usr/lib/x86_64-linux-gnu/xfce4/panel/plugins/libsystray.so 4 14680108 systray Notification Area Area where notification icons appear
rez 28060 0.0 0.5 517992 23188 ? Sl mar30 0:07 /usr/lib/x86_64-linux-gnu/xfce4/panel-plugins/xfce4-indicator-plugin 5 14680109 indicator Indicator Plugin An indicator of something that needs your attention on the desktop
rez 28062 0.0 0.4 452116 17196 ? Sl mar30 0:06 /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper /usr/lib/x86_64-linux-gnu/xfce4/panel-plugins/libnotes.so 12 14680121 xfce4-notes-plugin Notes Ideal for your quick notes
rez 28063 0.0 0.5 260536 21088 ? Sl mar30 0:15 /usr/lib/x86_64-linux-gnu/xfce4/panel-plugins/xfce4-xkb-plugin 28 14680122 xkb-plugin Keyboard Layouts Keyboard layouts setup and switch plugin
root 28891 0.0 0.0 0 0 ? S mar31 0:20 [kworker/1:1]
root 29208 0.0 0.0 0 0 ? S< 09:43 0:00 [kworker/u5:1]
avahi 29548 0.0 0.0 32348 1584 ? S mar28 0:00 avahi-daemon: registering [rez-Vostro.local]
avahi 29550 0.0 0.0 32228 420 ? S mar28 0:00 avahi-daemon: chroot helper
root 30645 0.0 0.0 25248 1356 ? Ss mar29 0:03 hostapd -B /etc/hostapd-hotspot.conf -f /tmp/hostapd.log
and here the output of free -m
total used free shared buffers cached
Mem: 3949 2512 1436 0 241 1164
-/+ buffers/cache: 1106 2842
Swap: 1715 55 1660
As you can see (even though not all threads are shown in the picture) the memory taken by the threads won't add up to anything close to 2512/3949=64%.
So, what is taking up all this memory? Can it be the kernel treads (whose amount of memory is not displayed) or a leak in Ubuntu itself?
Something which may be relevant is that the ammount of used memory shown by XFCE task manager is significantly lower than what free -m shows.
By default,
freeshows also memory used by cache and buffersIn the
free -moutput, as already said in the comments, you have to look to the lineto see exactly the quantity of memory used by applications, kernel and modules. In this case, you are using 1106 MB, which is almost 28% of the total memory. The rest is taken by the usual buffers and cache that helps the kernel to access files quicker.
The
psoutput shows the memory used by processIn the
psoutput I see that you still have the whole graphical desktop running, with a lot of components running. They take about 13% of the memory.And the modules...
The delta between the
pscalculation and thefreeis constituted of the memory taken by the kernel and the modules loaded. As the size column of thelsmodoutput only displays the size of the module on the filesystem (so the syse of the .ko file from which this module is loaded) it is not reliable to measure the memory used by them. A more reliable approach to measure the memory used by modules is to use theslabtoputilities (installed from the procps package.Also see the content of
/proc/meminfo, it gives the total usage of the Slab memory, the memory used to efficiently allocate memory to kernel objects. (See Wikipedia for more details on Slab).In conclusion
Memory usage is a complex domain, and you will need more than one tool to see in details which piece of memory is used by what.
free,ps,slabtop,/proc/meminfocontent,top,vmstat,htop, ... all they can bring a piece of information helpfull to build the full picture on your particular memory usage.