How can I measure the actual memory usage of an application or process?

Question

How do you measure the memory usage of an application or process in Linux?

From the blog article of Understanding memory usage on Linux, ps is not an accurate tool to use for this intent.

Why ps is "wrong"

Depending on how you look at it, ps is not reporting the real memory usage of processes. What it is really doing is showing how much real memory each process would take up if it were the only process running. Of course, a typical Linux machine has several dozen processes running at any given time, which means that the VSZ and RSS numbers reported by ps are almost definitely wrong.

_{(Note: This question is covered here in great detail.)}

Answer 1

Try the pmap command:

sudo pmap -x <process pid>

It would breakdown the memory allocated by process and shared libraries

Eg: sudo pmap -x <vscode cpptools>

Address           Kbytes     RSS   Dirty Mode  Mapping
0000000000400000   12444    4152       0 r-x-- cpptools-srv
0000000001027000      36      36       8 r---- cpptools-srv
0000000001030000     368      36      12 rw--- cpptools-srv
000000000108c000    4240    2120    2120 rw---   [ anon ]
0000000001e09000       4       0       0 -----   [ anon ]
0000000001e0a000       8       8       8 rw---   [ anon ]
00007fa3cddad000      48      44      44 rw---   [ anon ]

For more details, uses X switch

Example: sudo pmap -X <vscode cpptools>

     Address Perm   Offset Device  Inode  Size  Rss  Pss Referenced Anonymous LazyFree ShmemPmdMapped FilePmdMapped Shared_Hugetlb Private_Hugetlb Swap SwapPss Locked THPeligible Mapping
    00400000 r-xp 00000000  08:20 898178 12444 4152  345       4152         0        0              0             0              0               0    0       0      0           0 cpptools-srv
    01027000 r--p 00c26000  08:20 898178    36   36   10         36         8        0              0             0              0               0    0       0      0           0 cpptools-srv
    01030000 rw-p 00c2f000  08:20 898178   368   36   13         36        12        0              0             0              0               0    0       0      0           0 cpptools-srv
    0108c000 rw-p 00000000  00:00      0  4240 2120 2120       2084      2120        0              0             0              0               0    0       0      0           1
    01e09000 ---p 00000000  00:00      0     4    0    0          0         0        0              0             0              0               0    0       0      0           0 [heap]
    01e0a000 rw-p 00000000  00:00      0     8    8    8          8         8        0              0             0              0               0    0       0      0           0 [heap]
7fa3cddad000 rw-p 00000000  00:00      0    48   44   44         24        44        0              0             0              0               0    0       0      0           0
7fa3cddba000 rw-p 00000000  00:00      0    12    8    8          8         8        0              0             0              0               0    0       0      0           0
7fa3cddbe000 rw-p 00000000  00:00      0     4    4    4          4         4        0              0             0              0               0    0       0      0           0

Answer 2

I found heaptrack much easier to use than valgrind.

sudo apt install heaptrack heaptrack_gui
heaptrack my-program args
heaptrack_gui *.zst

Answer 3

With ps or similar tools you will only get the amount of memory pages allocated by that process. This number is correct, but:

• does not reflect the actual amount of memory used by the application, only the amount of memory reserved for it

• can be misleading if pages are shared, for example by several threads or by using dynamically linked libraries

If you really want to know what amount of memory your application actually uses, you need to run it within a profiler. For example, Valgrind can give you insights about the amount of memory used, and, more importantly, about possible memory leaks in your program. The heap profiler tool of Valgrind is called 'massif':

Massif is a heap profiler. It performs detailed heap profiling by taking regular snapshots of a program's heap. It produces a graph showing heap usage over time, including information about which parts of the program are responsible for the most memory allocations. The graph is supplemented by a text or HTML file that includes more information for determining where the most memory is being allocated. Massif runs programs about 20x slower than normal.

As explained in the Valgrind documentation, you need to run the program through Valgrind:

valgrind --tool=massif <executable> <arguments>

Massif writes a dump of memory usage snapshots (e.g. massif.out.12345). These provide, (1) a timeline of memory usage, (2) for each snapshot, a record of where in your program memory was allocated. A great graphical tool for analyzing these files is massif-visualizer. But I found ms_print, a simple text-based tool shipped with Valgrind, to be of great help already.

To find memory leaks, use the (default) memcheck tool of valgrind.

Newer tools I did not try myself are HeapTrack and the heap profiler in gperftools.

Answer 4

Given some of the answers (thanks thomasrutter), to get the actual swap and RAM for a single application, I came up with the following, say we want to know what 'firefox' is using

sudo smem | awk '/firefox/{swap += $5; pss += $7;} END {print "swap = "swap/1024" PSS = "pss/1024}'

Or for libvirt;

sudo smem | awk '/libvirt/{swap += $5; pss += $7;} END {print "swap = "swap/1024" PSS = "pss/1024}'

This will give you the total in MB like so;

swap = 0 PSS = 2096.92

swap = 224.75 PSS = 421.455

Tested on ubuntu 16.04 through 20.04.

Answer 5

ps -eo size,pid,user,command --sort -size | \
    awk '{ hr=$1/1024 ; printf("%13.2f Mb ",hr) } { for ( x=4 ; x<=NF ; x++ ) { printf("%s ",$x) } print "" }' |\
    cut -d "" -f2 | cut -d "-" -f1

Use this as root and you can get a clear output for memory usage by each process.

Output example:

     0.00 Mb COMMAND
  1288.57 Mb /usr/lib/firefox
   821.68 Mb /usr/lib/chromium/chromium
   762.82 Mb /usr/lib/chromium/chromium
   588.36 Mb /usr/sbin/mysqld
   547.55 Mb /usr/lib/chromium/chromium
   523.92 Mb /usr/lib/tracker/tracker
   476.59 Mb /usr/lib/chromium/chromium
   446.41 Mb /usr/bin/gnome
   421.62 Mb /usr/sbin/libvirtd
   405.11 Mb /usr/lib/chromium/chromium
   302.60 Mb /usr/lib/chromium/chromium
   291.46 Mb /usr/lib/chromium/chromium
   284.56 Mb /usr/lib/chromium/chromium
   238.93 Mb /usr/lib/tracker/tracker
   223.21 Mb /usr/lib/chromium/chromium
   197.99 Mb /usr/lib/chromium/chromium
   194.07 Mb conky
   191.92 Mb /usr/lib/chromium/chromium
   190.72 Mb /usr/bin/mongod
   169.06 Mb /usr/lib/chromium/chromium
   155.11 Mb /usr/bin/gnome
   136.02 Mb /usr/lib/chromium/chromium
   125.98 Mb /usr/lib/chromium/chromium
   103.98 Mb /usr/lib/chromium/chromium
    93.22 Mb /usr/lib/tracker/tracker
    89.21 Mb /usr/lib/gnome
    80.61 Mb /usr/bin/gnome
    77.73 Mb /usr/lib/evolution/evolution
    76.09 Mb /usr/lib/evolution/evolution
    72.21 Mb /usr/lib/gnome
    69.40 Mb /usr/lib/evolution/evolution
    68.84 Mb nautilus
    68.08 Mb zeitgeist
    60.97 Mb /usr/lib/tracker/tracker
    59.65 Mb /usr/lib/evolution/evolution
    57.68 Mb apt
    55.23 Mb /usr/lib/gnome
    53.61 Mb /usr/lib/evolution/evolution
    53.07 Mb /usr/lib/gnome
    52.83 Mb /usr/lib/gnome
    51.02 Mb /usr/lib/udisks2/udisksd
    50.77 Mb /usr/lib/evolution/evolution
    50.53 Mb /usr/lib/gnome
    50.45 Mb /usr/lib/gvfs/gvfs
    50.36 Mb /usr/lib/packagekit/packagekitd
    50.14 Mb /usr/lib/gvfs/gvfs
    48.95 Mb /usr/bin/Xwayland :1024
    46.21 Mb /usr/bin/gnome
    42.43 Mb /usr/bin/zeitgeist
    42.29 Mb /usr/lib/gnome
    41.97 Mb /usr/lib/gnome
    41.64 Mb /usr/lib/gvfs/gvfsd
    41.63 Mb /usr/lib/gvfs/gvfsd
    41.55 Mb /usr/lib/gvfs/gvfsd
    41.48 Mb /usr/lib/gvfs/gvfsd
    39.87 Mb /usr/bin/python /usr/bin/chrome
    37.45 Mb /usr/lib/xorg/Xorg vt2
    36.62 Mb /usr/sbin/NetworkManager
    35.63 Mb /usr/lib/caribou/caribou
    34.79 Mb /usr/lib/tracker/tracker
    33.88 Mb /usr/sbin/ModemManager
    33.77 Mb /usr/lib/gnome
    33.61 Mb /usr/lib/upower/upowerd
    33.53 Mb /usr/sbin/gdm3
    33.37 Mb /usr/lib/gvfs/gvfsd
    33.36 Mb /usr/lib/gvfs/gvfs
    33.23 Mb /usr/lib/gvfs/gvfs
    33.15 Mb /usr/lib/at
    33.15 Mb /usr/lib/at
    30.03 Mb /usr/lib/colord/colord
    29.62 Mb /usr/lib/apt/methods/https
    28.06 Mb /usr/lib/zeitgeist/zeitgeist
    27.29 Mb /usr/lib/policykit
    25.55 Mb /usr/lib/gvfs/gvfs
    25.55 Mb /usr/lib/gvfs/gvfs
    25.23 Mb /usr/lib/accountsservice/accounts
    25.18 Mb /usr/lib/gvfs/gvfsd
    25.15 Mb /usr/lib/gvfs/gvfs
    25.15 Mb /usr/lib/gvfs/gvfs
    25.12 Mb /usr/lib/gvfs/gvfs
    25.10 Mb /usr/lib/gnome
    25.10 Mb /usr/lib/gnome
    25.07 Mb /usr/lib/gvfs/gvfsd
    24.99 Mb /usr/lib/gvfs/gvfs
    23.26 Mb /usr/lib/chromium/chromium
    22.09 Mb /usr/bin/pulseaudio
    19.01 Mb /usr/bin/pulseaudio
    18.62 Mb (sd
    18.46 Mb (sd
    18.30 Mb /sbin/init
    18.17 Mb /usr/sbin/rsyslogd
    17.50 Mb gdm
    17.42 Mb gdm
    17.09 Mb /usr/lib/dconf/dconf
    17.09 Mb /usr/lib/at
    17.06 Mb /usr/lib/gvfs/gvfsd
    16.98 Mb /usr/lib/at
    16.91 Mb /usr/lib/gdm3/gdm
    16.86 Mb /usr/lib/gvfs/gvfsd
    16.86 Mb /usr/lib/gdm3/gdm
    16.85 Mb /usr/lib/dconf/dconf
    16.85 Mb /usr/lib/dconf/dconf
    16.73 Mb /usr/lib/rtkit/rtkit
    16.69 Mb /lib/systemd/systemd
    13.13 Mb /usr/lib/chromium/chromium
    13.13 Mb /usr/lib/chromium/chromium
    10.92 Mb anydesk
     8.54 Mb /sbin/lvmetad
     7.43 Mb /usr/sbin/apache2
     6.82 Mb /usr/sbin/apache2
     6.77 Mb /usr/sbin/apache2
     6.73 Mb /usr/sbin/apache2
     6.66 Mb /usr/sbin/apache2
     6.64 Mb /usr/sbin/apache2
     6.63 Mb /usr/sbin/apache2
     6.62 Mb /usr/sbin/apache2
     6.51 Mb /usr/sbin/apache2
     6.25 Mb /usr/sbin/apache2
     6.22 Mb /usr/sbin/apache2
     3.92 Mb bash
     3.14 Mb bash
     2.97 Mb bash
     2.95 Mb bash
     2.93 Mb bash
     2.91 Mb bash
     2.86 Mb bash
     2.86 Mb bash
     2.86 Mb bash
     2.84 Mb bash
     2.84 Mb bash
     2.45 Mb /lib/systemd/systemd
     2.30 Mb (sd
     2.28 Mb /usr/bin/dbus
     1.84 Mb /usr/bin/dbus
     1.46 Mb ps
     1.21 Mb openvpn hackthebox.ovpn
     1.16 Mb /sbin/dhclient
     1.16 Mb /sbin/dhclient
     1.09 Mb /lib/systemd/systemd
     0.98 Mb /sbin/mount.ntfs /dev/sda3 /media/n0bit4/Data
     0.97 Mb /lib/systemd/systemd
     0.96 Mb /lib/systemd/systemd
     0.89 Mb /usr/sbin/smartd
     0.77 Mb /usr/bin/dbus
     0.76 Mb su
     0.76 Mb su
     0.76 Mb su
     0.76 Mb su
     0.76 Mb su
     0.76 Mb su
     0.75 Mb sudo su
     0.75 Mb sudo su
     0.75 Mb sudo su
     0.75 Mb sudo su
     0.75 Mb sudo su
     0.75 Mb sudo su
     0.74 Mb /usr/bin/dbus
     0.71 Mb /usr/lib/apt/methods/http
     0.68 Mb /bin/bash /usr/bin/mysqld_safe
     0.68 Mb /sbin/wpa_supplicant
     0.66 Mb /usr/bin/dbus
     0.61 Mb /lib/systemd/systemd
     0.54 Mb /usr/bin/dbus
     0.46 Mb /usr/sbin/cron
     0.45 Mb /usr/sbin/irqbalance
     0.43 Mb logger
     0.41 Mb awk { hr=$1/1024 ; printf("%13.2f Mb ",hr) } { for ( x=4 ; x<=NF ; x++ ) { printf("%s ",$x) } print "" }
     0.40 Mb /usr/bin/ssh
     0.34 Mb /usr/lib/chromium/chrome
     0.32 Mb cut
     0.32 Mb cut
     0.00 Mb [kthreadd]
     0.00 Mb [ksoftirqd/0]
     0.00 Mb [kworker/0:0H]
     0.00 Mb [rcu_sched]
     0.00 Mb [rcu_bh]
     0.00 Mb [migration/0]
     0.00 Mb [lru
     0.00 Mb [watchdog/0]
     0.00 Mb [cpuhp/0]
     0.00 Mb [cpuhp/1]
     0.00 Mb [watchdog/1]
     0.00 Mb [migration/1]
     0.00 Mb [ksoftirqd/1]
     0.00 Mb [kworker/1:0H]
     0.00 Mb [cpuhp/2]
     0.00 Mb [watchdog/2]
     0.00 Mb [migration/2]
     0.00 Mb [ksoftirqd/2]
     0.00 Mb [kworker/2:0H]
     0.00 Mb [cpuhp/3]
     0.00 Mb [watchdog/3]
     0.00 Mb [migration/3]
     0.00 Mb [ksoftirqd/3]
     0.00 Mb [kworker/3:0H]
     0.00 Mb [kdevtmpfs]
     0.00 Mb [netns]
     0.00 Mb [khungtaskd]
     0.00 Mb [oom_reaper]
     0.00 Mb [writeback]
     0.00 Mb [kcompactd0]
     0.00 Mb [ksmd]
     0.00 Mb [khugepaged]
     0.00 Mb [crypto]
     0.00 Mb [kintegrityd]
     0.00 Mb [bioset]
     0.00 Mb [kblockd]
     0.00 Mb [devfreq_wq]
     0.00 Mb [watchdogd]
     0.00 Mb [kswapd0]
     0.00 Mb [vmstat]
     0.00 Mb [kthrotld]
     0.00 Mb [ipv6_addrconf]
     0.00 Mb [acpi_thermal_pm]
     0.00 Mb [ata_sff]
     0.00 Mb [scsi_eh_0]
     0.00 Mb [scsi_tmf_0]
     0.00 Mb [scsi_eh_1]
     0.00 Mb [scsi_tmf_1]
     0.00 Mb [scsi_eh_2]
     0.00 Mb [scsi_tmf_2]
     0.00 Mb [scsi_eh_3]
     0.00 Mb [scsi_tmf_3]
     0.00 Mb [scsi_eh_4]
     0.00 Mb [scsi_tmf_4]
     0.00 Mb [scsi_eh_5]
     0.00 Mb [scsi_tmf_5]
     0.00 Mb [bioset]
     0.00 Mb [kworker/1:1H]
     0.00 Mb [kworker/3:1H]
     0.00 Mb [kworker/0:1H]
     0.00 Mb [kdmflush]
     0.00 Mb [bioset]
     0.00 Mb [kdmflush]
     0.00 Mb [bioset]
     0.00 Mb [jbd2/sda5
     0.00 Mb [ext4
     0.00 Mb [kworker/2:1H]
     0.00 Mb [kauditd]
     0.00 Mb [bioset]
     0.00 Mb [drbd
     0.00 Mb [irq/27
     0.00 Mb [i915/signal:0]
     0.00 Mb [i915/signal:1]
     0.00 Mb [i915/signal:2]
     0.00 Mb [ttm_swap]
     0.00 Mb [cfg80211]
     0.00 Mb [kworker/u17:0]
     0.00 Mb [hci0]
     0.00 Mb [hci0]
     0.00 Mb [kworker/u17:1]
     0.00 Mb [iprt
     0.00 Mb [iprt
     0.00 Mb [kworker/1:0]
     0.00 Mb [kworker/3:0]
     0.00 Mb [kworker/0:0]
     0.00 Mb [kworker/2:0]
     0.00 Mb [kworker/u16:0]
     0.00 Mb [kworker/u16:2]
     0.00 Mb [kworker/3:2]
     0.00 Mb [kworker/2:1]
     0.00 Mb [kworker/1:2]
     0.00 Mb [kworker/0:2]
     0.00 Mb [kworker/2:2]
     0.00 Mb [kworker/0:1]
     0.00 Mb [scsi_eh_6]
     0.00 Mb [scsi_tmf_6]
     0.00 Mb [usb
     0.00 Mb [bioset]
     0.00 Mb [kworker/3:1]
     0.00 Mb [kworker/u16:1]

Answer 6

/prox/xxx/numa_maps gives some info there: N0=??? N1=???. But this result might be lower than the actual result, as it only counts those which have been touched.

Answer 7

Based on an answer to a related question.

You may use SNMP to get the memory and CPU usage of a process in a particular device on the network :)

Requirements:

• The device running the process should have snmp installed and running
• snmp should be configured to accept requests from where you will run the script below (it may be configured in file snmpd.conf)
• You should know the process ID (PID) of the process you want to monitor

Notes:

• HOST-RESOURCES-MIB::hrSWRunPerfCPU is the number of centi-seconds of the total system's CPU resources consumed by this process. Note that on a multi-processor system, this value may increment by more than one centi-second in one centi-second of real (wall clock) time.

• HOST-RESOURCES-MIB::hrSWRunPerfMem is the total amount of real system memory allocated to this process.

Process monitoring script

echo "IP address: "
read ip
echo "Specfiy PID: "
read pid
echo "Interval in seconds: "
read interval

while [ 1 ]
do
    date
    snmpget -v2c -c public $ip HOST-RESOURCES-MIB::hrSWRunPerfCPU.$pid
    snmpget -v2c -c public $ip HOST-RESOURCES-MIB::hrSWRunPerfMem.$pid
    sleep $interval;
done

Answer 8

I am using Arch Linux and there's this wonderful package called ps_mem:

ps_mem -p <pid>

Example Output

$ ps_mem -S -p $(pgrep firefox)

Private   +   Shared  =  RAM used   Swap used   Program

355.0 MiB +  38.7 MiB = 393.7 MiB    35.9 MiB   firefox
---------------------------------------------
                        393.7 MiB    35.9 MiB
=============================================

Answer 9

Use time.

Not the Bash builtin time, but the one you can find with which time, for example /usr/bin/time.

Here's what it covers, on a simple ls:

$ /usr/bin/time --verbose ls
(...)
Command being timed: "ls"
User time (seconds): 0.00
System time (seconds): 0.00
Percent of CPU this job got: 0%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 2372
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 1
Minor (reclaiming a frame) page faults: 121
Voluntary context switches: 2
Involuntary context switches: 9
Swaps: 0
File system inputs: 256
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0

Answer 10

Beside the solutions listed in the answers, you can use the Linux command "top". It provides a dynamic real-time view of the running system, and it gives the CPU and memory usage for the whole system, along with for every program, in percentage:

top

to filter by a program PID:

top -p <PID>

To filter by a program name:

top | grep <PROCESS NAME>

"top" provides also some fields such as:

VIRT -- Virtual Image (kb): The total amount of virtual memory used by the task

RES -- Resident size (kb): The non-swapped physical memory a task has used ; RES = CODE + DATA.

DATA -- Data+Stack size (kb): The amount of physical memory devoted to other than executable code, also known as the 'data resident set' size or DRS.

SHR -- Shared Mem size (kb): The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other processes.

Reference here.

Answer 11

Use the in-built System Monitor GUI tool available in Ubuntu.

Answer 12

While this question seems to be about examining currently running processes, I wanted to see the peak memory used by an application from start to finish. Besides Valgrind, you can use tstime, which is much simpler. It measures the "highwater" memory usage (RSS and virtual). From this answer.

Answer 13

Note: this works 100% well only when memory consumption increases

If you want to monitor memory usage by given process (or group of processed sharing common name, e.g. google-chrome, you can use my bash-script:

while true; do ps aux | awk ‚{print $5, $11}’ | grep chrome | sort -n > /tmp/a.txt; sleep 1; diff /tmp/{b,a}.txt; mv /tmp/{a,b}.txt; done;

this will continuously look for changes and print them.

Answer 14

Check out this shell script to check memory usage by application in Linux.

It is also available on GitHub and in a version without paste and bc.

Answer 15

If the process is not using up too much memory (either because you expect this to be the case, or some other command has given this initial indication), and the process can withstand being stopped for a short period of time, you can try to use the gcore command.

gcore <pid>

Check the size of the generated core file to get a good idea how much memory a particular process is using.

This won't work too well if process is using hundreds of megabytes, or gigabytes, as the core generation could take several seconds or minutes to be created depending on I/O performance. During the core creation the process is stopped (or "frozen") to prevent memory changes. So be careful.

Also make sure the mount point where the core is generated has plenty of disk space and that the system will not react negatively to the core file being created in that particular directory.

Answer 16

The below command line will give you the total memory used by the various process running on the Linux machine in MB:

ps -eo size,pid,user,command --sort -size | awk '{ hr=$1/1024 ; printf("%13.2f Mb ",hr) } { for ( x=4 ; x<=NF ; x++ ) { printf("%s ",$x) } print "" }' | awk '{total=total + $1} END {print total}'

Answer 17

Use smem, which is an alternative to ps which calculates the USS and PSS per process. You probably want the PSS.

• USS - Unique Set Size. This is the amount of unshared memory unique to that process (think of it as U for unique memory). It does not include shared memory. Thus this will under-report the amount of memory a process uses, but it is helpful when you want to ignore shared memory.

• PSS - Proportional Set Size. This is what you want. It adds together the unique memory (USS), along with a proportion of its shared memory divided by the number of processes sharing that memory. Thus it will give you an accurate representation of how much actual physical memory is being used per process - with shared memory truly represented as shared. Think of the P being for physical memory.

How this compares to RSS as reported by ps and other utilities:

• RSS - Resident Set Size. This is the amount of shared memory plus unshared memory used by each process. If any processes share memory, this will over-report the amount of memory actually used, because the same shared memory will be counted more than once - appearing again in each other process that shares the same memory. Thus it is fairly unreliable, especially when high-memory processes have a lot of forks - which is common in a server, with things like Apache or PHP (FastCGI/FPM) processes.

Notice: smem can also (optionally) output graphs such as pie charts and the like. IMO you don't need any of that. If you just want to use it from the command line like you might use ps -A v, then you don't need to install the Python and Matplotlib recommended dependency.

Answer 18

I'm using htop; it's a very good console program similar to Windows Task Manager.

Answer 19

A good test of the more "real world" usage is to open the application, run vmstat -s, and check the "active memory" statistic. Close the application, wait a few seconds, and run vmstat -s again.

However much active memory was freed was in evidently in use by the application.

Answer 20

Valgrind can show detailed information, but it slows down the target application significantly, and most of the time it changes the behavior of the application.

Exmap was something I didn't know yet, but it seems that you need a kernel module to get the information, which can be an obstacle.

I assume what everyone wants to know with respect to "memory usage" is the following... In Linux, the amount of physical memory a single process might use can be roughly divided into following categories.

• M.a anonymous mapped memory

• .p private

  • .d dirty == malloc/mmapped heap and stack allocated and written memory
  • .c clean == malloc/mmapped heap and stack memory once allocated, written, then freed, but not reclaimed yet

• .s shared

  • .d dirty == malloc/mmaped heap could get copy-on-write and shared among processes (edited)
  • .c clean == malloc/mmaped heap could get copy-on-write and shared among processes (edited)

• M.n named mapped memory

• .p private

  • .d dirty == file mmapped written memory private
  • .c clean == mapped program/library text private mapped

• .s shared

  • .d dirty == file mmapped written memory shared
  • .c clean == mapped library text shared mapped

Utility included in Android called showmap is quite useful

virtual                    shared   shared   private  private
size     RSS      PSS      clean    dirty    clean    dirty    object
-------- -------- -------- -------- -------- -------- -------- ------------------------------
       4        0        0        0        0        0        0 0:00 0                  [vsyscall]
       4        4        0        4        0        0        0                         [vdso]
      88       28       28        0        0        4       24                         [stack]
      12       12       12        0        0        0       12 7909                    /lib/ld-2.11.1.so
      12        4        4        0        0        0        4 89529                   /usr/lib/locale/en_US.utf8/LC_IDENTIFICATION
      28        0        0        0        0        0        0 86661                   /usr/lib/gconv/gconv-modules.cache
       4        0        0        0        0        0        0 87660                   /usr/lib/locale/en_US.utf8/LC_MEASUREMENT
       4        0        0        0        0        0        0 89528                   /usr/lib/locale/en_US.utf8/LC_TELEPHONE
       4        0        0        0        0        0        0 89527                   /usr/lib/locale/en_US.utf8/LC_ADDRESS
       4        0        0        0        0        0        0 87717                   /usr/lib/locale/en_US.utf8/LC_NAME
       4        0        0        0        0        0        0 87873                   /usr/lib/locale/en_US.utf8/LC_PAPER
       4        0        0        0        0        0        0 13879                   /usr/lib/locale/en_US.utf8/LC_MESSAGES/SYS_LC_MESSAGES
       4        0        0        0        0        0        0 89526                   /usr/lib/locale/en_US.utf8/LC_MONETARY
       4        0        0        0        0        0        0 89525                   /usr/lib/locale/en_US.utf8/LC_TIME
       4        0        0        0        0        0        0 11378                   /usr/lib/locale/en_US.utf8/LC_NUMERIC
    1156        8        8        0        0        4        4 11372                   /usr/lib/locale/en_US.utf8/LC_COLLATE
     252        0        0        0        0        0        0 11321                   /usr/lib/locale/en_US.utf8/LC_CTYPE
     128       52        1       52        0        0        0 7909                    /lib/ld-2.11.1.so
    2316       32       11       24        0        0        8 7986                    /lib/libncurses.so.5.7
    2064        8        4        4        0        0        4 7947                    /lib/libdl-2.11.1.so
    3596      472       46      440        0        4       28 7933                    /lib/libc-2.11.1.so
    2084        4        0        4        0        0        0 7995                    /lib/libnss_compat-2.11.1.so
    2152        4        0        4        0        0        0 7993                    /lib/libnsl-2.11.1.so
    2092        0        0        0        0        0        0 8009                    /lib/libnss_nis-2.11.1.so
    2100        0        0        0        0        0        0 7999                    /lib/libnss_files-2.11.1.so
    3752     2736     2736        0        0      864     1872                         [heap]
      24       24       24        0        0        0       24 [anon]
     916      616      131      584        0        0       32                         /bin/bash
-------- -------- -------- -------- -------- -------- -------- ------------------------------
   22816     4004     3005     1116        0      876     2012 TOTAL

Answer 21

In recent versions of Linux, use the smaps subsystem. For example, for a process with a PID of 1234:

cat /proc/1234/smaps

It will tell you exactly how much memory it is using at that time. More importantly, it will divide the memory into private and shared, so you can tell how much memory your instance of the program is using, without including memory shared between multiple instances of the program.

Answer 22

There isn't a single answer for this because you can't pin point precisely the amount of memory a process uses. Most processes under Linux use shared libraries.

For instance, let's say you want to calculate memory usage for the 'ls' process. Do you count only the memory used by the executable 'ls' (if you could isolate it)? How about libc? Or all these other libraries that are required to run 'ls'?

linux-gate.so.1 =>  (0x00ccb000)
librt.so.1 => /lib/librt.so.1 (0x06bc7000)
libacl.so.1 => /lib/libacl.so.1 (0x00230000)
libselinux.so.1 => /lib/libselinux.so.1 (0x00162000)
libc.so.6 => /lib/libc.so.6 (0x00b40000)
libpthread.so.0 => /lib/libpthread.so.0 (0x00cb4000)
/lib/ld-linux.so.2 (0x00b1d000)
libattr.so.1 => /lib/libattr.so.1 (0x00229000)
libdl.so.2 => /lib/libdl.so.2 (0x00cae000)
libsepol.so.1 => /lib/libsepol.so.1 (0x0011a000)

You could argue that they are shared by other processes, but 'ls' can't be run on the system without them being loaded.

Also, if you need to know how much memory a process needs in order to do capacity planning, you have to calculate how much each additional copy of the process uses. I think /proc/PID/status might give you enough information of the memory usage at a single time. On the other hand, Valgrind will give you a better profile of the memory usage throughout the lifetime of the program.

Answer 23

Another vote for Valgrind here, but I would like to add that you can use a tool like Alleyoop to help you interpret the results generated by Valgrind.

I use the two tools all the time and always have lean, non-leaky code to proudly show for it ;)

Answer 24

There isn't any easy way to calculate this. But some people have tried to get some good answers:

• ps_mem.py
• ps_mem.py at GitHub

Answer 25

Get Valgrind. Give it your program to run, and it'll tell you plenty about its memory usage.

This would apply only for the case of a program that runs for some time and stops. I don't know if Valgrind can get its hands on an already-running process or shouldn't-stop processes such as daemons.

Answer 26

It is hard to tell for sure, but here are two "close" things that can help.

$ ps aux

will give you Virtual Size (VSZ)

You can also get detailed statistics from the /proc file-system by going to /proc/$pid/status.

The most important is the VmSize, which should be close to what ps aux gives.

/proc/19420$ cat status
Name:      firefox
State:     S (sleeping)
Tgid:      19420
Pid:       19420
PPid:      1
TracerPid: 0
Uid:       1000    1000    1000    1000
Gid:       1000    1000    1000    1000
FDSize:    256
Groups:    4 6 20 24 25 29 30 44 46 107 109 115 124 1000
VmPeak:    222956 kB
VmSize:    212520 kB
VmLck:          0 kB
VmHWM:     127912 kB
VmRSS:     118768 kB
VmData:    170180 kB
VmStk:        228 kB
VmExe:         28 kB
VmLib:      35424 kB
VmPTE:        184 kB
Threads:   8
SigQ:      0/16382
SigPnd:    0000000000000000
ShdPnd:    0000000000000000
SigBlk:    0000000000000000
SigIgn:    0000000020001000
SigCgt:    000000018000442f
CapInh:    0000000000000000
CapPrm:    0000000000000000
CapEff:    0000000000000000
Cpus_allowed:    03
Mems_allowed:    1
voluntary_ctxt_switches:    63422
nonvoluntary_ctxt_switches: 7171

Answer 27

If your code is in C or C++ you might be able to use getrusage() which returns you various statistics about memory and time usage of your process.

Not all platforms support this though and will return 0 values for the memory-use options.

Instead you can look at the virtual file created in /proc/[pid]/statm (where [pid] is replaced by your process id. You can obtain this from getpid()).

This file will look like a text file with 7 integers. You are probably most interested in the first (all memory use) and sixth (data memory use) numbers in this file.

Answer 28

I would suggest that you use atop. You can find everything about it on this page. It is capable of providing all the necessary KPI for your processes and it can also capture to a file.

Answer 29

Three more methods to try:

1. ps aux --sort pmem
   It sorts the output by %MEM.
2. ps aux | awk '{print $2, $4, $11}' | sort -k2r | head -n 15
   It sorts using pipes.
3. top -a
   It starts top sorting by %MEM

(Extracted from here)

Answer 30

If you want something quicker than profiling with Valgrind and your kernel is older and you can't use smaps, a ps with the options to show the resident set of the process (with ps -o rss,command) can give you a quick and reasonable _aproximation_ of the real amount of non-swapped memory being used.