8 Notes on memtype parameter in proc.mem items

Overview

The memtype parameter is supported on Linux, AIX, FreeBSD, and Solaris platforms.

Three common values of 'memtype' are supported on all of these platforms: pmem, rss and vsize. Additionally, platform-specific 'memtype' values are supported on some platforms.

AIX

See values supported for 'memtype' parameter on AIX in the table.

Supported value	Description	Source in procentry64 structure	Tries to be compatible with
vsize (( - default value))	Virtual memory size	pi_size
pmem	Percentage of real memory	pi_prm	ps -o pmem
rss	Resident set size	pi_trss + pi_drss	ps -o rssize
size	Size of process (code + data)	pi_dvm	"ps gvw" SIZE column
dsize	Data size	pi_dsize
tsize	Text (code) size	pi_tsize	"ps gvw" TSIZ column
sdsize	Data size from shared library	pi_sdsize
drss	Data resident set size	pi_drss
trss	Text resident set size	pi_trss

Notes for AIX:

When choosing parameters for proc.mem[] item key on AIX, try to specify narrow process selection criteria. Otherwise there is a risk of getting unwanted processes counted into proc.mem[] result.

Example:

\$ zabbix_agentd -t proc.mem[,,,NonExistingProcess,rss]
       proc.mem[,,,NonExistingProcess,rss]           [u|2879488]

This example shows how specifying only command line (regular expression to match) parameter results in Zabbix agent self-accounting - probably not what you want.

Do not use "ps -ef" to browse processes - it shows only non-kernel processes. Use "ps -Af" to see all processes which will be seen by Zabbix agent.
Let's go through example of 'topasrec' how Zabbix agent proc.mem[] selects processes.

\$ ps -Af | grep topasrec
       root 10747984        1   0   Mar 16      -  0:00 /usr/bin/topasrec  -L -s 300 -R 1 -r 6 -o /var/perf daily/ -ypersistent=1 -O type=bin -ystart_time=04:08:54,Mar16,2023

proc.mem[] has arguments:

proc.mem[<name>,<user>,<mode>,<cmdline>,<memtype>]

The 1st criterion is a process name (argument <name>). In our example Zabbix agent will see it as 'topasrec'. In order to match, you need to either specify 'topasrec' or to leave it empty. The 2nd criterion is a user name (argument <user>). To match, you need to either specify 'root' or to leave it empty. The 3rd criterion used in process selection is an argument <cmdline>. Zabbix agent will see its value as '/usr/bin/topasrec -L -s 300 -R 1 -r 6 -o /var/perf/daily/ -ypersistent=1 -O type=bin -ystart_time=04:08:54,Mar16,2023'. To match, you need to either specify a regular expression which matches this string or to leave it empty.

Arguments <mode> and <memtype> are applied after using the three criteria mentioned above.

FreeBSD

See values supported for 'memtype' parameter on FreeBSD in the table.

Supported value	Description	Source in kinfo_proc structure	Tries to be compatible with
vsize	Virtual memory size	kp_eproc.e_vm.vm_map.size or ki_size	ps -o vsz
pmem	Percentage of real memory	calculated from rss	ps -o pmem
rss	Resident set size	kp_eproc.e_vm.vm_rssize or ki_rssize	ps -o rss
size (( - default value))	Size of process (code + data + stack)	tsize + dsize + ssize
tsize	Text (code) size	kp_eproc.e_vm.vm_tsize or ki_tsize	ps -o tsiz
dsize	Data size	kp_eproc.e_vm.vm_dsize or ki_dsize	ps -o dsiz
ssize	Stack size	kp_eproc.e_vm.vm_ssize or ki_ssize	ps -o ssiz

Linux

See values supported for 'memtype' parameter on Linux in the table.

Supported value	Description	Source in /proc/<pid>/status file
vsize (( - default value))	Virtual memory size	VmSize
pmem	Percentage of real memory	(VmRSS/total_memory) * 100
rss	Resident set size	VmRSS
data	Size of data segment	VmData
exe	Size of code segment	VmExe
hwm	Peak resident set size	VmHWM
lck	Size of locked memory	VmLck
lib	Size of shared libraries	VmLib
peak	Peak virtual memory size	VmPeak
pin	Size of pinned pages	VmPin
pte	Size of page table entries	VmPTE
size	Size of process code + data + stack segments	VmExe + VmData + VmStk
stk	Size of stack segment	VmStk
swap	Size of swap space used	VmSwap

Notes for Linux:

Not all 'memtype' values are supported by older Linux kernels. For example, Linux 2.4 kernels do not support hwm, pin, peak, pte and swap values.
We have noticed that self-monitoring of the Zabbix agent active check process with proc.mem[...,...,...,...,data] shows a value that is 4 kB larger than reported by VmData line in the agent's /proc/<pid>/status file. At the time of self-measurement the agent's data segment increases by 4 kB and then returns to the previous size.

Solaris

See values supported for 'memtype' parameter on Solaris in the table.

Supported value	Description	Source in psinfo structure	Tries to be compatible with
vsize (( - default value))	Size of process image	pr_size	ps -o vsz
pmem	Percentage of real memory	pr_pctmem	ps -o pmem
rss	Resident set size It may be underestimated - see rss description in "man ps".	pr_rssize	ps -o rss

Footnotes

¹ Default value.

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