Find Out What Processes Are Using Swap Space

| 分类 Linux  | 标签 linux  process 

Reposted from: http://www.cyberciti.biz/faq/linux-which-process-is-using-swap/

Linux: Find Out What Process Are Using Swap Space

T he top and free command display the total amount of free and used physical and swap memory in the server. How do I determine which process is using swap space under Linux operating systems? How do I find out swap space usage of particular process such as memcached ?

You can use the any one of the following techniques but keep in mind that because of shared pages, there is no reliable way to get this information [ 1 ]

[ a ] /proc/meminfo – This file reports statistics about memory usage on the system. It is used by free to report the amount of free and used memory (both physical and swap) on the system as well as the shared memory and buffers used by the kernel. You can also use free, vmstat and other tools to find out the same information .

[ b ] /proc/${PID}/smaps , /proc/${PID}/status , and /proc/${PID}/stat : Use these files to find information about memory, pages and swap used by each process using its PID.

[ c ] smem – This command (python script) reports memory usage with shared memory divided proportionally.

Finding out process ID and swap usage

Type the following pidof command to find the process ID of a running program called memcached :
# pidof memcached
Alternatively, use pgrep command to lookup process PID , enter:
# pgrep memcached
Sample outputs (note down PID number #1):

        48440

To see swap space used by memcached (PID # 48440 ), enter (number #2):
# grep --color VmSwap /proc/ 48440 /status
Sample outputs (number #4):

        VmSwap:       900 kB

Or the following awk command (number #3):
# awk '/VmSwap/{print $2 " " $3}' /proc/ 48440 /status
Sample outputs (number #4):

Fig.01: Finding out memcached process swap usage

Fig.01: Finding out memcached process swap usage

Listing all process swap space usage

Type the following bash for loop command to see swap space usage per process:

                  
                    for
                  
                    file
                  
                    in
                  
                    /
                  proc
                    /*/
                  status ; 
                    do
                  
                    awk
                  
                    '/VmSwap|Name/{printf $2 " " $3}END{ print ""}'
                  
                    $file
                  ; 
                    done
                

Type the following command to sort out output:

                  
                    for
                  
                    file
                  
                    in
                  
                    /
                  proc
                    /*/
                  status ; 
                    do
                  
                    awk
                  
                    '/VmSwap|Name/{printf $2 " " $3}END{ print ""}'
                  
                    $file
                  ; 
                    done
                  
                    |  |
                  
                    sort
                  
                    -k
                  
                    2
                  
                    -n
                  
                    -r
                  
                    |  |
                  
                    less
                

Sample outputs:

        php-cgi 11964 kB
        php-cgi 11016 kB
        php-cgi 10392 kB
        php-cgi 10336 kB
        php-cgi 9844 kB
        php-cgi 9780 kB
        php-cgi 8584 kB
        php-cgi 7996 kB
        php-cgi 7960 kB
        php-cgi 7956 kB
        php-cgi 7796 kB
        php-cgi 7540 kB
        php-cgi 6884 kB
        squid 6864 kB
        php-cgi 6640 kB
        php-cgi 6556 kB
        php-cgi 5848 kB
        php-cgi 5744 kB
        php-cgi 5636 kB
        php-cgi 5592 kB
        php-cgi 5488 kB
        php-cgi 5132 kB
        php-cgi 4584 kB
        php-cgi 4508 kB
        php-cgi 4388 kB
        lighttpd 4100 kB
        php-cgi 3984 kB
        php-cgi 3644 kB
        php-cgi 3616 kB
        php-cgi 3604 kB
        rpc.mountd 3580 kB
        ....
        ..
      

Say hello to smem

The smem command reports physical memory usage, taking shared memory pages into account. Unshared memory is reported as the USS (Unique Set Size). Shared memory is divided evenly among the processes sharing that memory. The unshared memory (USS) plus a process’s proportion of shared memory is reported as the PSS (Proportional Set Size). The USS and PSS only include physical memory usage. They do not include memory that has been swapped out to disk. Memory can be reported by process, by user, by mapping, or system-wide. Both text mode and graphical output are available.

Installation

To install smem [ 2 ] type the following command under Debian / Ubuntu Linux:
$ sudo apt-get install smem
RHEL / CentOS Linux user type the following command:
$ wget http://www.selenic.com/smem/download/smem-1.2.tar.gz
$ tar xvf smem-1.2.tar.gz
# cp /tmp/smem-1.2/smem /usr/local/bin/
# chmod +x /usr/local/bin/smem

How do I use smem command?

The syntax is:

        smem [option]
        ## This lets smem include the size of the kernel's code and statically allocated data in the systemwide (-w) output ##
        smem -K /path/to/kernel/image/on/disk [option]
        ## Amount of physical RAM.  This lets smem detect the amount of memory used by firmware/hardware in the systemwide (-w) output.
        ## If  provided, it will also be used as the total memory size to base percentages on.
        smem -R REALMEMSIZE [option]
      

To see basic process information, enter:
# smem
Sample outputs:

        PID User     Command                         Swap      USS      PSS      RSS
        53369 xxxxxxx  /usr/bin/php-cgi                2788        0        0        8
        53387 xxxxxxx  /usr/bin/php-cgi                2796        0        0        8
        36227 xxxxxxx  /usr/bin/php-cgi                2324        0        1        8
        36232 xxxxxxx  /usr/bin/php-cgi                2324        0        1        4
        36233 xxxxxxx  /usr/bin/php-cgi                2324        0        1        4
        46733 xxxxxxx  /usr/bin/php-cgi                2904        0        2        8
        46739 xxxxxxxx /usr/bin/php-cgi                2904        0        2        4
        3623 root     ssh-agent                        576        4        4        4
        53378 xxxxxxx  /usr/bin/php-cgi                2788        4        4        8
        53396 vivek    /usr/bin/php-cgi                2788        4        4        8
        7855 root     rpc.rquotad                      144        4        6      116
        7480 root     ssh-agent                        604        4        7      112
        34832 root     ssh-agent                        576        4        7       92
        7334 root     /sbin/mingetty /dev/tty1          76        4       19      436
        7336 root     /sbin/mingetty /dev/tty2          76        4       19      436
        7338 root     /sbin/mingetty /dev/tty3          76        4       19      436
        7340 root     /sbin/mingetty /dev/tty4          80        4       19      436
        7346 root     /sbin/mingetty /dev/tty5          80        4       19      436
        7350 root     /sbin/mingetty /dev/tty6          76        4       19      436
        7332 root     /sbin/agetty /dev/ttyS1 192       80        4       22      460
        53405 raj      /usr/bin/php-cgi                2760       32       32       36
        7780 rpcuser  rpc.statd                       3568        4       41      668
      

To see library-oriented view, enter:
# smem -m
To see user-oriented view, enter:
# smem -u
Sample outputs:

        User     Count     Swap      USS      PSS      RSS
        rpcuser      1     3568        4       41      668
        vivek        4     7300       44       73      564
        xxxxxxxx     3     6120       56       77      524
        rpc          1      200       68      104      596
        raj          1      468      272      300      892
        ntp          1      316      324      367     1036
        cdnnginx     1      420      572      603     1216
      

To see systemwide memory usage summary pass the -w option:
# smem -w
Sample outputs:

        Area                           Used      Cache   Noncache
        firmware/hardware                 0          0          0
        kernel image                      0          0          0
        kernel dynamic memory       5302144    5137920     164224
        userspace memory            2692196     240828    2451368
        free memory                  126228     126228          0
      

To see system view
# smem -R 8G -K /path/to/vmlinux/on/disk -w
To see totals and percentages, enter:
# smem -t -p
Sample outputs:

        PID User     Command                         Swap      USS      PSS      RSS
        53369 xxxxxxx  /usr/bin/php-cgi               0.04%    0.00%    0.00%    0.00%
        53387 xxxxxxx  /usr/bin/php-cgi               0.04%    0.00%    0.00%    0.00%
        36227 xxxxxxx  /usr/bin/php-cgi               0.04%    0.00%    0.00%    0.00%
        36232 xxxxxxx  /usr/bin/php-cgi               0.04%    0.00%    0.00%    0.00%
        36233 xxxxxxx  /usr/bin/php-cgi               0.04%    0.00%    0.00%    0.00%
        46733 xxxxxxxy /usr/bin/php-cgi               0.05%    0.00%    0.00%    0.00%
        46739 xxxxxxxy /usr/bin/php-cgi               0.05%    0.00%    0.00%    0.00%
        3623 root     ssh-agent                      0.01%    0.00%    0.00%    0.00%
        53378 xxxxxxx  /usr/bin/php-cgi               0.04%    0.00%    0.00%    0.00%
        53396 xxxxxxx  /usr/bin/php-cgi               0.04%    0.00%    0.00%    0.00%
        7855 root     rpc.rquotad                    0.00%    0.00%    0.00%    0.00%
        7480 root     ssh-agent                      0.01%    0.00%    0.00%    0.00%
        34832 root     ssh-agent                      0.01%    0.00%    0.00%    0.00%
        7334 root     /sbin/mingetty /dev/tty1       0.00%    0.00%    0.00%    0.00%
        7336 root     /sbin/mingetty /dev/tty2       0.00%    0.00%    0.00%    0.00%
        7338 root     /sbin/mingetty /dev/tty3       0.00%    0.00%    0.00%    0.00%
        .....
        ..
        ...
        65304 vivek    /usr/bin/php-cgi               0.00%    0.16%    0.27%    0.61%
        33931 vivek    /usr/bin/php-cgi               0.00%    0.14%    0.28%    0.44%
        47933 squid    (squid) -f /etc/squid/squid    0.11%    2.69%    2.69%    2.71%
        28410 mysql    /usr/libexec/mysqld --based    0.01%    3.67%    3.67%    3.68%
        48440 memcached memcached -d -p 11211 -u me    0.01%    4.41%    4.41%    4.41%
        -------------------------------------------------------------------------------
        191 24                                      5.36%   16.08%   19.43%   27.24%
      

Options

Type the following command to see all other supported options:
# smem --help
Sample outputs:

        -h, --help            show this help message and exit
        -H, --no-header       disable header line
        -c COLUMNS, --columns=COLUMNS
        columns to show
        -t, --totals          show totals
        -R REALMEM, --realmem=REALMEM
        amount of physical RAM
        -K KERNEL, --kernel=KERNEL
        path to kernel image
        -m, --mappings        show mappings
        -u, --users           show users
        -w, --system          show whole system
        -P PROCESSFILTER, --processfilter=PROCESSFILTER
        process filter regex
        -M MAPFILTER, --mapfilter=MAPFILTER
        map filter regex
        -U USERFILTER, --userfilter=USERFILTER
        user filter regex
        -n, --numeric         numeric output
        -s SORT, --sort=SORT  field to sort on
        -r, --reverse         reverse sort
        -p, --percent         show percentage
        -k, --abbreviate      show unit suffixes
        --pie=PIE             show pie graph
        --bar=BAR             show bar graph
        -S SOURCE, --source=SOURCE
        /proc data source
      

A note about top command

Type the top command as root:
# top
To sort process as per swap page usage (SWAP = VIRT – RES) type capital O (option) followed by p (small p ) and [Enter] key:

Fig.02 top command - sored process by swap usage

Fig.02 top command – process sorted by swap usage (click to enlarge)

References:
  1. ^ From the htop faq page :

    It is not possible to get the exact size of used swap space of a process. The top command fakes this information by making SWAP = VIRT – RES, but that is not a good metric, because other stuff such as video memory counts on VIRT as well (for example: top says my X process is using 81M of swap, but it also reports my system as a whole is using only 2M of swap. Therefore, I will not add a similar Swap column to htop because I don’t know a reliable way to get this information (actually, I don’t think it’s possible to get an exact number, because of shared pages).

  2. ^ smem memory reporting tool can be downloaded by visiting this page .
  3. man pages: top, free, htop, vmstat, smem, and proc(5)

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