What is using my swap space?
How can I know which process is using my swap space on my Linux system?
Swap space is not necessarily used by specific processes.
More precisely: Where are consumed each of those 244 MB of swap?
Files stored on tmpfs based file systems might be using them (tmpfs first uses RAM as back-end but, not to waste RAM, can paginate out to the swap area blocks that are not actively used).
Check the output of :
df -ht tmpfs
The
/proc/PID/smapsis an extension based on maps, showing the memory consumption for each of the process's mappings. For each of mappings there is a series of lines such as the following:08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash Size: 1084 kB Rss: 892 kB Pss: 374 kB Shared_Clean: 892 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 0 kB Referenced: 892 kB Anonymous: 0 kB LazyFree: 0 kB AnonHugePages: 0 kB ShmemPmdMapped: 0 kB Shared_Hugetlb: 0 kB Private_Hugetlb: 0 kB Swap: 0 kB SwapPss: 0 kB KernelPageSize: 4 kB MMUPageSize: 4 kB Locked: 0 kB VmFlags: rd ex mr mw me dw
Try
$ for proc in /proc/*; do cat $proc/smaps 2>/dev/null | awk '/Swap/{swap+=$2}END{print swap "\tKB\t'`readlink $proc/exe|awk '{print $1}' `'" }'; done | sort -n | awk '{total+=$1}/[0-9]/;END{print total "\tKB\tTotal"}'
0 KB /usr/bin/bash
0 KB /usr/bin/bash
0 KB /usr/bin/bash
0 KB /usr/bin/bash
0 KB /usr/bin/bash
0 KB /usr/bin/docker-containerd
0 KB /usr/bin/docker-containerd-shim
0 KB /usr/bin/docker-containerd-shim
0 KB /usr/bin/docker-proxy
0 KB /usr/bin/docker-proxy
0 KB /usr/bin/docker-proxy
0 KB /usr/bin/gawk
0 KB /usr/bin/readlink
0 KB /usr/bin/sleep
0 KB /usr/bin/sort
0 KB /usr/bin/ssh
0 KB /usr/bin/ssh
0 KB /usr/bin/ssh-agent
0 KB /usr/libexec/postfix/pickup
0 KB /usr/libexec/postfix/qmgr
0 KB /usr/sbin/atd
0 KB /usr/sbin/dnsmasq
0 KB /usr/sbin/dnsmasq
0 KB /usr/sbin/sedispatch
0 KB /usr/sbin/sshd
0 KB /usr/sbin/sshd
28 KB /usr/sbin/chronyd
32 KB /usr/sbin/audispd
84 KB /usr/sbin/avahi-daemon
88 KB /usr/lib/systemd/systemd-logind
100 KB /usr/bin/tail
104 KB /usr/sbin/crond
156 KB /usr/sbin/avahi-daemon
192 KB /usr/lib/systemd/systemd-journald
196 KB /usr/bin/bash
196 KB /usr/bin/dbus-launch
...
14872 KB /usr/bin/Xvnc
20048 KB /usr/lib64/firefox/firefox
40176 KB /usr/lib64/firefox/firefox
108848 KB /usr/sbin/mysqld
267144 KB Total
This actually says mysql is using the most swap.
$ free -k
total used free shared buff/cache available
Mem: 1883740 1044212 112132 14320 727396 520304
Swap: 2097148 265784 1831364
free's ouput doesn't seem too much off in my case