Class: Sys::ProcTable::Smaps

Inherits:
Object
  • Object
show all
Defined in:
lib/linux/sys/proctable/smaps.rb

Overview

Smaps represents a process’ memory size for all mapped files

A single mapped file memory entry looks like this:

00400000-004d4000 r-xp 00000000 fd:00 785                      /bin/bash
Size:                848 kB
Rss:                 572 kB
Pss:                 572 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:       572 kB
Private_Dirty:         0 kB
Referenced:          572 kB
Anonymous:             0 kB
AnonHugePages:         0 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB

Have a look at ‘man 5 proc` on a linux distribution, to get some more information about the lines and fields in `/proc//smaps`.

Example:

smaps = Smaps.new(123, IO.read("/proc/1234/smaps")

# result

#<Sys::ProcTable::Smaps:0x007f8ac5930768
  @pid=123,
  @pss=107000,
  @rss=368000,
  @uss=96000,
  @swap=192000,
  @vss=136752000
>

smaps.pss  # => 109568
smaps.rss  # => 376832
smaps.uss  # => 98304
smaps.swap # => 196608
smaps.vss  # => 140034048

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(pid, smaps_contents) ⇒ Smaps

Create a new smaps object

This expects a process id and a string containing the contents of /proc/PID/smaps - see ‘man 5 proc` for a reference.

The smaps contents are parsed and memory sizes are calculated in bytes.



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# File 'lib/linux/sys/proctable/smaps.rb', line 100

def initialize(pid, smaps_contents)
  @pid            = pid
  @pss            = 0
  @rss            = 0
  @uss            = 0
  @swap           = 0
  @vss            = 0
  smaps_contents.each_line { |line| parse_smaps_line(line) }
end

Instance Attribute Details

#pid ⇒ Object (readonly)

Process ID for this smaps



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# File 'lib/linux/sys/proctable/smaps.rb', line 50

def pid
  @pid
end

#pss ⇒ Object (readonly) Also known as: proportional_set_size

Proportional set size

PSS is the size of private pages added to each shared mapping’s size divided by the number of processes that share it. It is meant to provide a better representation of the amount of memory actually used by a process.

If a process has 4k of private pages, 4k of shared pages shared with one other process, and 3k of pages shared with two other processes, the PSS is:

4k + (4k / 2) + (3k / 3) = 7k



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# File 'lib/linux/sys/proctable/smaps.rb', line 65

def pss
  @pss
end

#rss ⇒ Object (readonly) Also known as: resident_set_size

Resident set size

RSS is the total size of all pages, shared or not, mapped to a process.



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# File 'lib/linux/sys/proctable/smaps.rb', line 71

def rss
  @rss
end

#swap ⇒ Object (readonly)

Swap

Swap is the total size of all swapped pages mapped to a process.



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# File 'lib/linux/sys/proctable/smaps.rb', line 83

def swap
  @swap
end

#uss ⇒ Object (readonly) Also known as: unique_set_size

Unique set size

USS is the total size of all private pages mapped to a process.



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# File 'lib/linux/sys/proctable/smaps.rb', line 77

def uss
  @uss
end

#vss ⇒ Object (readonly) Also known as: virtual_set_size

Virtual set size

VSS is the total accessible address space in a process. Since files are lazily loaded, this value represents the total size of all mapped files if they were all loaded.



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# File 'lib/linux/sys/proctable/smaps.rb', line 90

def vss
  @vss
end