smem - Process Memory Usage Report

Linux Tutorials - Herong's Tutorial Examples

∟smem - Process Memory Usage Report

This section provides a tutorial on how to install 'smem' and use it to report memory usage of each running process.

What Is smem? - "smem" is a tool that can give numerous reports on memory usage on Linux systems. Here is what I did to install and use "smem" on my CentOS 8 computer.

1. Intall "smem".

herong$ sudo dnf install smem

Installed:
  smem-1.5-6.el8.noarch

2. Run "smem" with default options. It displays memory usage of each process.

herong$ sudo smem

  PID User    Command                       Swap   USS   PSS    RSS 
 1849 root    /usr/libexec/sssd/sssd_nss      88  4204  4885  11288 
59583 apache  php-fpm: pool www               48  3712  4890  19232 
53605 apache  /usr/sbin/httpd -DFOREGROUN    100  4112  5040  15172 
 1221 root    /usr/lib/systemd/systemd-ud     16  5456  5556   9724 
 2484 root    /usr/sbin/rpc.mountd          7936  6384  6433   7916 
 2479 rpcuser /usr/sbin/rpc.statd          16156  9124  9137  10728 
...

The memory usage fields in the output are:

Swap - Swap space used by the process in KiB.
USS (Unique Set Size) - RAM used exclusively by the process in KiB.
PSS (Proportional Set Size) - Sum of proportional portion of each shared object in RAM by the process in KiB.
RSS (Resident Set Size) - RAM used by the process (exclusively and shared memory) in KiB.

3. Run "smem -t" to report the total counts at the end.

herong$ sudo smem -t 

  PID User    Command                 Swap     USS     PSS     RSS 
...
 1169 root    /usr/lib/systemd/sy        0   23964   50023   82168 
 2479 rpcuser /usr/sbin/rpc.statd    16156    9124    9137   10728 
 1998 mysql   /usr/libexec/mysqld   388728  653368  653741  656520 
------------------------------------------------------------------
  148 19                           6479428 6413180 6508005 6812112

4. Run "smem -s uss" to sort the output by USS size.

herong$ sudo smem -s uss 

  PID User  Command                      Swap  USS  PSS  RSS 
 2921 root  /usr/sbin/dnsmasq --conf-fi   444    0    2    4 
 1484 root  /usr/sbin/rpc.idmapd          608    4    4    8 
 1532 root  /usr/sbin/mcelog --ignoreno   152    4    4    8 
...

5. Run "smem -r -s uss" to sort the output by USS size in descending order.

herong$ sudo smem -r -s uss 

  PID User   Command                 Swap     USS     PSS     RSS 
 1998 mysql  /usr/libexec/mysqld   388728  653392  653749  656520 
 3399 gdm    /usr/bin/gnome-shell  142116   53212   54859   59672 
 3705 root   /usr/libexec/package   97520   17880   18517   22436 
...

6. Run "smem -w" to report systemwide memory usage summary.

herong$ sudo smem -w

Area                           Used      Cache   Noncache 
firmware/hardware                 0          0          0 
kernel image                      0          0          0 
kernel dynamic memory       7024568    5911676    1112892 
userspace memory            6503044     202880    6300164 
free memory                 2203836    2203836          0

7. Run "smem -m" to report memory usage of each program file that is loaded in the memory.

herong$ sudo smem -m

Map                                       PIDs   AVGPSS      PSS 
/dev/dri/card0                               1        0        0 
/dev/shm/squid-cf__metadata.shm              1        0        0 
/dev/shm/squid-cf__queues.shm                1        0        0 
/dev/shm/squid-cf__readers.shm               1        0        0 
/etc/udev/hwdb.bin                           1        0        0 
...

Compare "ps" and "smem" Reports - To help our understanding memory usage fields reported by "ps" and "smem" commands, let's compare their output for a single process:

herong$ sudo smem -P firewalld
  PID User  Command                       Swap  USS  PSS  RSS 
 1661 root  /usr/libexec/platform-pytho  25436   12   12   16 

herong$ ps -o pid,euser,%mem,rss,drs,trs,sz,vsz,comm -p 1661
  PID EUSER  %MEM  RSS     DRS  TRS     SZ     VSZ  COMMAND
 1661 root    0.0    0  321436    0  80359  321436  firewalld