.ds KA arrow key
.ds KS scrolling key
.ds MP physical memory
+.ds MS swap file
.ds MV virtual memory
.ds NT \fBNote\fR:
.ds PU CPU
.ds Xc see the
.ds XT See topic
.ds Xt see topic
+.ds XX See `OVERVIEW, Linux Memory Types' for additional details
.
.\" Document /////////////////////////////////////////////////////////////
.\" ----------------------------------------------------------------------
The remaining Table of Contents
.nf
+ OVERVIEW
+ Operation
+ Startup Defaults
+ Linux Memory Types
1. COMMAND\-LINE Options
2. SUMMARY Display
a. UPTIME and LOAD Averages
z \- color/mono On (show colors)
.fi
+.\" ......................................................................
+.SS Linux Memory Types
+.\" ----------------------------------------------------------------------
+For our purposes there are three types of memory, and one is optional.
+First is \*(MP, a limited resource where code and data must
+reside when executed or referenced.
+Next is the optional \*(MS, where modified (dirty) memory can be saved
+and later retrieved if too many demands are made on \*(MP.
+Lastly we have \*(MV, a nearly unlimited resource serving the
+following goals:
+
+.nf
+ 1. abstraction, free from physical memory addresses/limits
+ 2. isolation, every process in a separate address space
+ 3. sharing, a single mapping can serve multiple needs
+ 4. flexibility, assign a virtual address to a file
+.fi
+
+Regardless of which of these forms memory may take, all are managed as
+pages (typically 4096 bytes) but expressed by default in \*(We as
+KiB (kibibyte).
+The memory discussed under topic `2c. MEMORY Usage' deals with \*(MP
+and the \*(MS for the system as a whole.
+The memory reviewed in topic `3. FIELDS / Columns Display'
+embraces all three memory types, but for individual processes.
+
+For each such process, every memory page is restricted to a single
+quadrant from the table below.
+Both \*(MP and \*(MV can include any of the four, while the \*(MS only
+includes #1 through #3.
+The memory in quadrant #4, when modified, acts as its own dedicated \*(MS.
+
+.nf
+ \fBPrivate\fR | \fBShared\fR
+ \fB1\fR | \fB2\fR
+ \fBAnonymous\fR . stack |
+ . malloc() |
+ . brk()/sbrk() |
+ . mmap(PRIVATE, ANON) | . mmap(SHARED, ANON)
+ -----------------------+----------------------
+ . mmap(PRIVATE, fd) | . mmap(SHARED, fd)
+ \fBFile-backed\fR . pgms/shared libs |
+ \fB3\fR | \fB4\fR
+.fi
+
+The following may help in interpreting process level memory values displayed
+as columns and discussed in topic `3a. DESCRIPTIONS of Fields'.
+.nf
+ %MEM \- simply RES divided by total \*(MP
+ CODE \- the `pgms' portion of quadrant \fB3\fR
+ DATA \- the quadrant \fB1\fR portion of VIRT
+ RES \- anything occupying \*(MP (all quadrants)
+ SHR \- subset of RES (excludes \fB1\fR, includes all \fB2\fR & \fB4\fR, some \fB3\fR)
+ SWAP \- excludes quadrant \fB4\fR
+ USED \- simply the sum of RES and SWAP
+ VIRT \- everything in-use and/or reserved (all quadrants)
+.fi
+
+\*(NT Even though program images and shared libraries are considered
+\fIprivate\fR to a process, they will be accounted for as \fIshared\fR
+(SHR) by the kernel.
+
.\" ----------------------------------------------------------------------
.SH 1. COMMAND-LINE Options
.\" ----------------------------------------------------------------------
.TP 4
2.\fB %MEM \*(Em Memory Usage (RES) \fR
-A task's currently used share of available \*(MP.
+A task's currently resident share of available \*(MP.
+
+\*(XX.
.TP 4
3.\fB CGNAME \*(Em Control Group Name \fR
.TP 4
5.\fB CODE \*(Em Code Size (KiB) \fR
-The amount of \*(MP devoted to executable code, also known as
-the Text Resident Set size or TRS.
+The amount of \*(MP currently devoted to executable code, also known
+as the Text Resident Set size or TRS.
+
+\*(XX.
.TP 4
6.\fB COMMAND \*(Em Command\fB Name\fR or Command\fB Line \fR
Such memory may not yet be mapped to \*(MP (RES) but will always be
included in the \*(MV (VIRT) amount.
+\*(XX.
+
.TP 4
8.\fB ENVIRON \*(Em Environment variables \fR
Display all of the environment variables, if any, as seen by the
19.\fB RES \*(Em Resident Memory Size (KiB) \fR
A subset of the virtual address space (VIRT) representing the non-swapped
\*(MP a task is currently using.
-
It can include private anonymous pages, private pages mapped to files
(including program images and shared libraries) plus shared anonymous pages.
-All such memory is backed by the swap file represented separately under SWAP.
+All such memory is backed by the \*(MS represented separately under SWAP.
Lastly, this field may also include shared file-backed pages which, when
-modified, act as a dedicated swap file and thus will never impact SWAP.
+modified, act as a dedicated \*(MS and thus will never impact SWAP.
+
+\*(XX.
.TP 4
20.\fB RUID \*(Em Real User Id \fR
.TP 4
23.\fB SHR \*(Em Shared Memory Size (KiB) \fR
A subset of resident memory (RES) that may be used by other processes.
-
It will include shared anonymous pages and shared file-backed pages.
It also includes \fIprivate\fR pages mapped to files representing
program images and shared libraries.
+\*(XX.
+
.TP 4
24.\fB SID \*(Em Session Id \fR
A session is a collection of process groups (\*(Xa PGRP),
.TP 4
29.\fB SWAP \*(Em Swapped Size (KiB) \fR
-The non-resident portion of a task's address space.
+The formerly resident portion of a task's address space written
+to the \*(MS when \*(MP becomes over committed.
+
+\*(XX.
.TP 4
30.\fB TGID \*(Em Thread Group Id \fR
.TP 4
36.\fB USED \*(Em Memory in Use (KiB) \fR
-This field represents the non-swapped \*(MP a task has used (RES) plus
-the non-resident portion of its address space (SWAP).
+This field represents the non-swapped \*(MP a task is using (RES) plus
+the swapped out portion of its address space (SWAP).
+
+\*(XX.
.TP 4
37.\fB USER \*(Em User Name \fR
It includes all code, data and shared libraries plus pages that have been
swapped out and pages that have been mapped but not used.
+\*(XX.
+
.TP 4
39.\fB WCHAN \*(Em Sleeping in Function \fR
This field will show the name of the kernel function in which the task
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