How to see top processes sorted by actual memory u

问题:

I have a server with 12G of memory. A fragment of top is shown below:

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                                                                                                                                                                                      
12979 frank  20   0  206m  21m  12m S   11  0.2  26667:24 krfb                                                                                                                                                                                                                                                          
13 root      15  -5     0    0    0 S    1  0.0  36:25.04 ksoftirqd/3                                                                                                                                                                                                                                                   
59 root      15  -5     0    0    0 S    0  0.0   4:53.00 ata/2                                                                                                                                                                                                                                                         
2155 root      20   0  662m  37m 8364 S    0  0.3 338:10.25 Xorg                                                                                                                                                                                                                                                          
4560 frank  20   0  8672 1300  852 R    0  0.0   0:00.03 top                                                                                                                                                                                                                                                           
12981 frank  20   0  987m  27m  15m S    0  0.2  45:10.82 amarok                                                                                                                                                                                                                                                        
24908 frank  20   0 16648  708  548 S    0  0.0   2:08.84 wrapper                                                                                                                                                                                                                                                       
1 root      20   0  8072  608  572 S    0  0.0   0:47.36 init                                                                                                                                                                                                                                                          
2 root      15  -5     0    0    0 S    0  0.0   0:00.00 kthreadd

The free -m shows the following:

             total       used       free     shared    buffers     cached
Mem:         12038      11676        362          0        599       9745
-/+ buffers/cache:       1331      10706
Swap:         2204        257       1946

If I understand correctly, the system has only 362 MB of available memory. My question is: How can I find out which process is consuming most of the memory?

Just as background info, the system is running 64bit OpenSuse 12.

回答1:

First, repeat this mantra for a little while: "unused memory is wasted memory". The Linux kernel keeps around huge amounts of file metadata and files that were requested, until something that looks more important pushes that data out. It's why you can run:

find /home -type f -name '*.mp3'
find /home -type f -name '*.aac'

and have the second find instance run at ridiculous speed.

Linux only leaves a little bit of memory 'free' to handle spikes in memory usage without too much effort.

Second, you want to find the processes that are eating all your memory; in top use the M command to sort by memory use. Feel free to ignore the VIRT column, that just tells you how much virtual memory has been allocated, not how much memory the process is using. RES reports how much memory is resident, or currently in ram (as opposed to swapped to disk or never actually allocated in the first place, despite being requested).

But, since RES will count e.g. /lib/libc.so.6 memory once for nearly every process, it isn't exactly an awesome measure of how much memory a process is using. The SHR column reports how much memory is shared with other processes, but there is no guarantee that another process is actually sharing -- it could be sharable, just no one else wants to share.

The smem tool is designed to help users better gage just how much memory should really be blamed on each individual process. It does some clever work to figure out what is really unique, what is shared, and proportionally tallies the shared memory to the processes sharing it. smem may help you understand where your memory is going better than top will, but top is an excellent first tool.

回答2:

use quick tip using top command in linux/unix

$ top

and then hit Shift+m (i.e. write a capital M).

From man top

SORTING of task window
  For compatibility, this top supports most of the former top sort keys.
  Since this is primarily a service to former top users, these commands do
  not appear on any help screen.
    command   sorted-field                  supported
      A         start time (non-display)      No
      M         %MEM                          Yes
      N         PID                           Yes
      P         %CPU                          Yes
      T         TIME+                         Yes

Or alternatively: hit Shift + f , then choose the display to order by memory usage by hitting key n then press Enter. You will see active process ordered by memory usage

回答3:

ps aux | awk '{print $2, $4, $11}' | sort -k2rn | head -n 10

(Adding -n numeric flag to sort command.)

回答4:

First you should read an explanation on the output of free. Bottom line: you have at least 10.7 GB of memory readily usable by processes.

Then you should define what "memory usage" is for a process (it's not easy or unambiguous, trust me).

Then we might be able to help more :-)

回答5:

List and Sort Processes by Memory Usage:

ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNS

回答6:

ps aux --sort '%mem'

from procps' ps (default on Ubuntu 12.04) generates output like:

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
...
tomcat7   3658  0.1  3.3 1782792 124692 ?      Sl   10:12   0:25 /usr/lib/jvm/java-7-oracle/bin/java -Djava.util.logging.config.file=/var/lib/tomcat7/conf/logging.properties -D
root      1284  1.5  3.7 452692 142796 tty7    Ssl+ 10:11   3:19 /usr/bin/X -core :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
ciro      2286  0.3  3.8 1316000 143312 ?      Sl   10:11   0:49 compiz
ciro      5150  0.0  4.4 660620 168488 pts/0   Sl+  11:01   0:08 unicorn_rails worker[1] -p 3000 -E development -c config/unicorn.rb             
ciro      5147  0.0  4.5 660556 170920 pts/0   Sl+  11:01   0:08 unicorn_rails worker[0] -p 3000 -E development -c config/unicorn.rb             
ciro      5142  0.1  6.3 2581944 239408 pts/0  Sl+  11:01   0:17 sidekiq 2.17.8 gitlab [0 of 25 busy]                                                                          
ciro      2386  3.6 16.0 1752740 605372 ?      Sl   10:11   7:38 /usr/lib/firefox/firefox

So here Firefox is the top consumer with 16% of my memory.

You may also be interested in:

ps aux --sort '%cpu'

回答7:

you can specify which column to sort by, with following steps:

steps:
* top
* shift + F
* select a column from the list
    e.g. n means sort by memory,
* press enter
* ok

回答8:

You can see memory usage by executing this code in your terminal:

$ watch -n2 free -m
$ htop

回答9:

How to total up used memory by process name:

Sometimes even looking at the biggest single processes there is still a lot of used memory unaccounted for. To check if there are a lot of the same smaller processes using the memory you can use a command like the following which uses awk to sum up the total memory used by processes of the same name:

ps -e -orss=,args= |awk '{print $1 " " $2 }'| awk '{tot[$2]+=$1;count[$2]++} END {for (i in tot) {print tot[i],i,count[i]}}' | sort -n

e.g. output

9344 docker 1
9948 nginx: 4
22500 /usr/sbin/NetworkManager 1
24704 sleep 69
26436 /usr/sbin/sshd 15
34828 -bash 19
39268 sshd: 10
58384 /bin/su 28
59876 /bin/ksh 29
73408 /usr/bin/python 2
78176 /usr/bin/dockerd 1
134396 /bin/sh 84
5407132 bin/naughty_small_proc 1432
28061916 /usr/local/jdk/bin/java 7

回答10:

You have this simple command:

$ free -h