NAME
top - display Linux processesSYNOPSIS
top [options]DESCRIPTION
The top program provides a dynamic real-time view of a running system. It can display system summary information as well as a list of processes or threads currently being managed by the Linux kernel. The types of system summary information shown and the types, order and size of information displayed for processes are all user configurable and that configuration can be made persistent across restarts.OVERVIEW
Documentation
The remaining Table of ContentsOVERVIEW Operation Linux Memory Types 1. COMMAND-LINE Options 2. SUMMARY Display a. UPTIME and LOAD Averages b. TASK and CPU States c. MEMORY Usage 3. FIELDS / Columns Display a. DESCRIPTIONS of Fields b. MANAGING Fields 4. INTERACTIVE Commands a. GLOBAL Commands b. SUMMARY AREA Commands c. TASK AREA Commands 1. Appearance 2. Content 3. Size 4. Sorting d. COLOR Mapping 5. ALTERNATE-DISPLAY Provisions a. WINDOWS Overview b. COMMANDS for Windows c. SCROLLING a Window d. SEARCHING in a Window e. FILTERING in a Window 6. FILES a. PERSONAL Configuration File b. ADDING INSPECT Entries c. SYSTEM Configuration File d. SYSTEM Restrictions File 7. ENVIRONMENT VARIABLE(S) 8. STUPID TRICKS Sampler a. Kernel Magic b. Bouncing Windows c. The Big Bird Window d. The Ol' Switcheroo 9. BUGS, 10. SEE Also
Operation
When operating top, the two most important keys are the help (h or ?) key and quit (`q') key. Alternatively, you could simply use the traditional interrupt key (^C) when you're done.key/cmd objective ^Z suspend top fg resume top <Left> force a screen redraw (if necessary)
key/cmd objective reset restore your terminal settings
key equivalent-keys Left alt + h Down alt + j Up alt + k Right alt + l Home alt + ctrl + h PgDn alt + ctrl + j PgUp alt + ctrl + k End alt + ctrl + l
key special-significance Up recall older strings for re-editing Down recall newer strings or erase entire line Insert toggle between insert and overtype modes Delete character removed at cursor, moving others left Home jump to beginning of input line End jump to end of input line
Linux Memory Types
For our purposes there are three types of memory, and one is optional. First is physical memory, a limited resource where code and data must reside when executed or referenced. Next is the optional swap file, where modified (dirty) memory can be saved and later retrieved if too many demands are made on physical memory. Lastly we have virtual memory, a nearly unlimited resource serving the following goals: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
Private | Shared 1 | 2 Anonymous . stack | . malloc() | . brk()/sbrk() | . POSIX shm* . mmap(PRIVATE, ANON) | . mmap(SHARED, ANON) -----------------------+---------------------- . mmap(PRIVATE, fd) | . mmap(SHARED, fd) File-backed . pgms/shared libs | 3 | 4
%MEM - simply RES divided by total physical memory CODE - the `pgms' portion of quadrant 3 DATA - the entire quadrant 1 portion of VIRT plus all explicit mmap file-backed pages of quadrant 3 RES - anything occupying physical memory which, beginning with Linux-4.5, is the sum of the following three fields: RSan - quadrant 1 pages, which include any former quadrant 3 pages if modified RSfd - quadrant 3 and quadrant 4 pages RSsh - quadrant 2 pages RSlk - subset of RES which cannot be swapped out (any quadrant) SHR - subset of RES (excludes 1, includes all 2 & 4, some 3) SWAP - potentially any quadrant except 4 USED - simply the sum of RES and SWAP VIRT - everything in-use and/or reserved (all quadrants)
1. COMMAND-LINE Options
Mandatory arguments to long options are mandatory for short options too.- -b, --batch
- Starts top in Batch mode, which could be useful for sending output from top to other programs or to a file. In this mode, top will not accept input and runs until the iterations limit you've set with the `-n' command-line option or until killed.
- -c, --cmdline-toggle
- Starts top with the last remembered `c' state reversed. Thus, if top was displaying command lines, now that field will show program names, and vice versa. See the `c' interactive command for additional information.
- -d, --delay = SECS [.TENTHS]
- Specifies the delay between screen updates, and overrides the corresponding value in one's personal configuration file or the startup default. Later this can be changed with the `d' or `s' interactive commands. Fractional seconds are honored, but a negative number is not allowed. In all cases, however, such changes are prohibited if top is running in Secure mode, except for root (unless the `s' command-line option was used). For additional information on Secure mode see topic 6d. SYSTEM Restrictions File.
- -E, --scale-summary-mem = k | m | g | t | p | e
- Instructs top to force summary area memory to be scaled as:
k - kibibytes m - mebibytes g - gibibytes t - tebibytes p - pebibytes e - exbibytes
Later this can be changed with the `E' command toggle.
- -e, --scale-task-mem = k | m | g | t | p
- Instructs top to force task area memory to be scaled as:
k - kibibytes m - mebibytes g - gibibytes t - tebibytes p - pebibytes
Later this can be changed with the `e' command toggle.
- -H, --threads-show
- Instructs top to display individual threads. Without this command-line option a summation of all threads in each process is shown. Later this can be changed with the `H' interactive command.
- -h, --help
- Display usage help text, then quit.
- -i, --idle-toggle
- Starts top with the last remembered `i' state reversed. When this toggle is Off, tasks that have not used any CPU since the last update will not be displayed. For additional information regarding this toggle see topic 4c. TASK AREA Commands, SIZE.
- -n, --iterations = NUMBER
- Specifies the maximum number of iterations, or frames, top should produce before ending.
- -O, --list-fields
- This option acts as a form of help for the -o option shown below. It will cause top to print each of the available field names on a separate line, then quit. Such names are subject to NLS (National Language Support) translation.
- -o, --sort-override = FIELDNAME
- Specifies the name of the field on which tasks will be sorted, independent of what is reflected in the configuration file. You can prepend a `+' or `-' to the field name to also override the sort direction. A leading `+' will force sorting high to low, whereas a `-' will ensure a low to high ordering. This option exists primarily to support automated/scripted batch mode operation.
- -p, --pid = PIDLIST (as: 1,2, 3, ... or -p1 -p2 -p3 ...)
- Monitor only processes with specified process IDs. However, when combined with Threads mode (`H'), all processes in the thread group (see TGID) of each monitored PID will also be shown. This option can be given up to 20 times, or you can provide a comma delimited list with up to 20 pids. Co-mingling both approaches is permitted. A pid value of zero will be treated as the process id of the top program itself once it is running. This is a command-line option only and should you wish to return to normal operation, it is not necessary to quit and restart top -- just issue any of these interactive commands: `=', `u' or `U'. The `p', `u' and `U' command-line options are mutually exclusive.
- -S, --accum-time-toggle
- Starts top with the last remembered `S' state reversed. When Cumulative time mode is On, each process is listed with the cpu time that it and its dead children have used. See the `S' interactive command for additional information regarding this mode.
- -s, --secure-mode
- Starts top with secure mode forced, even for root. This mode is far better controlled through a system configuration file (see topic 6. FILES).
- -U, --filter-any-user = USER (as: number or name)
- Display only processes with a user id or user name matching that given. This option matches on any user (real, effective, saved, or filesystem). Prepending an exclamation point (`!') to the user id or name instructs top to display only processes with users not matching the one provided. The `p', `U' and `u' command-line options are mutually exclusive.
- -u, --filter-only-euser = USER (as: number or name)
- Display only processes with a user id or user name matching that given. This option matches on the effective user id only. Prepending an exclamation point (`!') to the user id or name instructs top to display only processes with users not matching the one provided. The `p', `U' and `u' command-line options are mutually exclusive.
- -V, --version
- Display version information, then quit.
- -w, --width [=COLUMNS]
- In Batch mode, when used without an argument top will format output using the COLUMNS= and LINES= environment variables, if set. Otherwise, width will be fixed at the maximum 512 columns. With an argument, output width can be decreased or increased (up to 512) but the number of rows is considered unlimited. In normal display mode, when used without an argument top will attempt to format output using the COLUMNS= and LINES= environment variables, if set. With an argument, output width can only be decreased, not increased. Whether using environment variables or an argument with -w, when not in Batch mode actual terminal dimensions can never be exceeded. Note: Without the use of this command-line option, output width is always based on the terminal at which top was invoked whether or not in Batch mode.
- -1, --single-cpu-toggle
- Starts top with the last remembered Cpu States portion of the summary area reversed. Either all cpu information will be displayed in a single line or each cpu will be displayed separately, depending on the state of the NUMA Node command toggle ('2'). See the `1' and '2' interactive commands for additional information.
2. SUMMARY Display
Each of the following three areas are individually controlled through one or more interactive commands. See topic 4b. SUMMARY AREA Commands for additional information regarding these provisions.2a. UPTIME and LOAD Averages
This portion consists of a single line containing:program or window name, depending on display mode current time and length of time since last boot total number of users system load avg over the last 1, 5 and 15 minutes
2b. TASK and CPU States
This portion consists of a minimum of two lines. In an SMP environment, additional lines can reflect individual CPU state percentages.running; sleeping; stopped; zombie
us : time running un-niced user processes sy : time running kernel processes ni : time running niced user processes id : time spent in the kernel idle handler wa : time waiting for I/O completion hi : time spent servicing hardware interrupts si : time spent servicing software interrupts st : time stolen from this vm by the hypervisor
a b c d %Cpu(s): 75.0/25.0 100[ ... ]
2c. MEMORY Usage
This portion consists of two lines which may express values in kibibytes (KiB) through exbibytes (EiB) depending on the scaling factor enforced with the `E' interactive command.total, free, used and buff/cache
total, free, used and avail (which is physical memory)
a b c GiB Mem : 18.7/15.738 [ ... ] GiB Swap: 0.0/7.999 [ ... ]
KiB = kibibyte = 1024 bytes MiB = mebibyte = 1024 KiB = 1,048,576 bytes GiB = gibibyte = 1024 MiB = 1,073,741,824 bytes TiB = tebibyte = 1024 GiB = 1,099,511,627,776 bytes PiB = pebibyte = 1024 TiB = 1,125,899,906,842,624 bytes EiB = exbibyte = 1024 PiB = 1,152,921,504,606,846,976 bytes
3. FIELDS / Columns
3a. DESCRIPTIONS of Fields
Listed below are top's available process fields (columns). They are shown in strict ascii alphabetical order. You may customize their position and whether or not they are displayable with the `f' (Fields Management) interactive command.- %CPU -- CPU Usage
- The task's share of the elapsed CPU time since the last screen update, expressed as a percentage of total CPU time. In a true SMP environment, if a process is multi-threaded and top is not operating in Threads mode, amounts greater than 100% may be reported. You toggle Threads mode with the `H' interactive command. Also for multi-processor environments, if Irix mode is Off, top will operate in Solaris mode where a task's cpu usage will be divided by the total number of CPUs. You toggle Irix/Solaris modes with the `I' interactive command. Note: When running in forest view mode (`V') with children collapsed (`v'), this field will also include the CPU time of those unseen children. See topic 4c. TASK AREA Commands, CONTENT for more information regarding the `V' and `v' toggles.
- %CUC -- CPU Utilization
- This field is identical to %CUU below, except the percentage also reflects reaped child processes.
- %CUU -- CPU Utilization
- A task's total CPU usage divided by its elapsed running time, expressed as a percentage. If a process currently displays high CPU usage, this field can help determine if such behavior is normal. Conversely, if a process has low CPU usage currently, %CUU may reflect historically higher demands over its lifetime.
- %MEM -- Memory Usage (RES)
- A task's currently resident share of available physical memory. See `OVERVIEW, Linux Memory Types' for additional details.
- AGID -- Autogroup Identifier
- The autogroup identifier associated with a process. This feature operates in conjunction with the CFS scheduler to improve interactive desktop performance. When /proc/sys/kernel/sched_autogroup_enabled is set, a new autogroup is created with each new session (see SID). All subsequently forked processes in that session inherit membership in this autogroup. The kernel then attempts to equalize distribution of CPU cycles across such groups. Thus, an autogroup with many CPU intensive processes (e.g make -j) will not dominate an autogroup with only one or two processes. When -1 is displayed it means this information is not available.
- AGNI -- Autogroup Nice Value
- The autogroup nice value which affects scheduling of all processes in that group. A negative nice value means higher priority, whereas a positive nice value means lower priority.
- CGNAME -- Control Group Name
- The name of the control group to which a process belongs, or `-' if not applicable for that process. This will typically be the last entry in the full list of control groups as shown under the next heading (CGROUPS). And as is true there, this field is also variable width.
- CGROUPS -- Control Groups
- The names of the control group(s) to which a process belongs, or `-' if not applicable for that process. Control Groups provide for allocating resources (cpu, memory, network bandwidth, etc.) among installation-defined groups of processes. They enable fine-grained control over allocating, denying, prioritizing, managing and monitoring those resources. Many different hierarchies of cgroups can exist simultaneously on a system and each hierarchy is attached to one or more subsystems. A subsystem represents a single resource. Note: The CGROUPS field, unlike most columns, is not fixed-width. When displayed, it plus any other variable width columns will be allocated all remaining screen width (up to the maximum 512 characters). Even so, such variable width fields could still suffer truncation. See topic 5c. SCROLLING a Window for additional information on accessing any truncated data.
- CODE -- Code Size (KiB)
- The amount of physical memory currently devoted to executable code, also known as the Text Resident Set size or TRS. See `OVERVIEW, Linux Memory Types' for additional details.
- COMMAND -- Command Name or Command Line
- Display the command line used to start a task or the name
of the associated program. You toggle between command line and
name with `c', which is both a command-line option and an interactive
command.
When you've chosen to display command lines, processes without a command
line (like kernel threads) will be shown with only the program name in
brackets, as in this example:
[kthreadd] This field may also be impacted by the forest view display mode. See the `V' interactive command for additional information regarding that mode. Note: The COMMAND field, unlike most columns, is not fixed-width. When displayed, it plus any other variable width columns will be allocated all remaining screen width (up to the maximum 512 characters). Even so, such variable width fields could still suffer truncation. This is especially true for this field when command lines are being displayed (the `c' interactive command.) See topic 5c. SCROLLING a Window for additional information on accessing any truncated data.
- DATA -- Data + Stack Size (KiB)
- The amount of private memory reserved by a process. It is also known as the Data Resident Set or DRS. Such memory may not yet be mapped to physical memory (RES) but will always be included in the virtual memory (VIRT) amount. See `OVERVIEW, Linux Memory Types' for additional details.
- ELAPSED -- Elapsed Running Time
- The length of time since a process was started. Thus, the most recently started task will display the smallest time interval. The value will be expressed as 'HH,MM' (hours,minutes) but is subject to additional scaling if the interval becomes too great to fit column width. At that point it will be scaled to 'DD+HH' (days+hours) and possibly beyond.
- ENVIRON -- Environment variables
- Display all of the environment variables, if any, as seen by the respective processes. These variables will be displayed in their raw native order, not the sorted order you are accustomed to seeing with an unqualified `set'. Note: The ENVIRON field, unlike most columns, is not fixed-width. When displayed, it plus any other variable width columns will be allocated all remaining screen width (up to the maximum 512 characters). Even so, such variable width fields could still suffer truncation. This is especially true for this field. See topic 5c. SCROLLING a Window for additional information on accessing any truncated data.
- EXE -- Executable Path
- Where available, this is the full path to the executable, including the program name. Note: The EXE field, unlike most columns, is not fixed-width. When displayed, it plus any other variable width columns will be allocated all remaining screen width (up to the maximum 512 characters).
- Flags -- Task Flags
- This column represents the task's current scheduling flags which are expressed in hexadecimal notation and with zeros suppressed. These flags are officially documented in <linux/sched.h>.
- GID -- Group Id
- The effective group ID.
- GROUP -- Group Name
- The effective group name.
- LOGID -- Login User Id
- The user ID used at login. When -1 is displayed it means this information is not available.
- LXC -- Lxc Container Name
- The name of the lxc container within which a task is running. If a process is not running inside a container, a dash (`-') will be shown.
- NI -- Nice Value
- The nice value of the task. A negative nice value means higher priority, whereas a positive nice value means lower priority. Zero in this field simply means priority will not be adjusted in determining a task's dispatch-ability. Note: This value only affects scheduling priority relative to other processes in the same autogroup. See the `AGID' and `AGNI' fields for additional information on autogroups.
- NU -- Last known NUMA node
- A number representing the NUMA node associated with the last used processor (`P'). When -1 is displayed it means that NUMA information is not available. See the `'2' and `3' interactive commands for additional NUMA provisions affecting the summary area.
- OOMa -- Out of Memory Adjustment Factor
- The value, ranging from -1000 to +1000, added to the current out of memory score (OOMs) which is then used to determine which task to kill when memory is exhausted.
- OOMs -- Out of Memory Score
- The value, ranging from 0 to +1000, used to select task(s) to kill when memory is exhausted. Zero translates to `never kill' whereas 1000 means `always kill'.
- P -- Last used CPU (SMP)
- A number representing the last used processor. In a true SMP environment this will likely change frequently since the kernel intentionally uses weak affinity. Also, the very act of running top may break this weak affinity and cause more processes to change CPUs more often (because of the extra demand for cpu time).
- PGRP -- Process Group Id
- Every process is member of a unique process group which is used for distribution of signals and by terminals to arbitrate requests for their input and output. When a process is created (forked), it becomes a member of the process group of its parent. By convention, this value equals the process ID (see PID) of the first member of a process group, called the process group leader.
- PID -- Process Id
- The task's unique process ID, which periodically wraps, though never restarting at zero. In kernel terms, it is a dispatchable entity defined by a task_struct. This value may also be used as: a process group ID (see PGRP); a session ID for the session leader (see SID); a thread group ID for the thread group leader (see TGID); and a TTY process group ID for the process group leader (see TPGID).
- PPID -- Parent Process Id
- The process ID (pid) of a task's parent.
- PR -- Priority
- The scheduling priority of the task. If you see `rt' in this field, it means the task is running under real time scheduling priority. Under linux, real time priority is somewhat misleading since traditionally the operating itself was not preemptible. And while the 2.6 kernel can be made mostly preemptible, it is not always so.
- PSS -- Proportional Resident Memory, smaps (KiB)
- The proportion of this task's share of `RSS' where each page is divided by the number of processes sharing it. It is also the sum of the `PSan', `PSfd' and `PSsh' fields. For example, if a process has 1000 resident pages alone and 1000 resident pages shared with another process, its `PSS' would be 1500 (times page size). Accessing smaps values is 10x more costly than other memory statistics and data for other users requires root privileges.
As was true for `PSS' above (total
proportional resident memory), these fields represent the proportion of this
task's share of each type of memory divided by the number of processes sharing
it.
Accessing smaps values is 10x more costly than other memory statistics and data
for other users requires root privileges.
- RES -- Resident Memory Size (KiB)
- A subset of the virtual address space (VIRT) representing the non-swapped physical memory a task is currently using. It is also the sum of the `RSan', `RSfd' and `RSsh' fields. 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. 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. See `OVERVIEW, Linux Memory Types' for additional details.
- RSS -- Resident Memory, smaps (KiB)
- Another, more precise view of process non-swapped physical memory. It is obtained from the `smaps_rollup' file and is generally slightly larger than that shown for `RES'. Accessing smaps values is 10x more costly than other memory statistics and data for other users requires root privileges.
- RSan -- Resident Anonymous Memory Size (KiB)
- A subset of resident memory (RES) representing private pages not mapped to a file.
- RSfd -- Resident File-Backed Memory Size (KiB)
- A subset of resident memory (RES) representing the implicitly shared pages supporting program images and shared libraries. It also includes explicit file mappings, both private and shared.
- RSlk -- Resident Locked Memory Size (KiB)
- A subset of resident memory (RES) which cannot be swapped out.
- RSsh -- Resident Shared Memory Size (KiB)
- A subset of resident memory (RES) representing the explicitly shared anonymous shm*/mmap pages.
- RUID -- Real User Id
- The real user ID.
- RUSER -- Real User Name
- The real user name.
- S -- Process Status
- The status of the task which can be one of:
D = uninterruptible sleep
I = idle
R = running
S = sleeping
T = stopped by job control signal
t = stopped by debugger during trace
Z = zombie Tasks shown as running should be more properly thought of as ready to run -- their task_struct is simply represented on the Linux run-queue. Even without a true SMP machine, you may see numerous tasks in this state depending on top's delay interval and nice value.
- SHR -- Shared Memory Size (KiB)
- 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 private pages mapped to files representing program images and shared libraries. See `OVERVIEW, Linux Memory Types' for additional details.
- SID -- Session Id
- A session is a collection of process groups (see PGRP), usually established by the login shell. A newly forked process joins the session of its creator. By convention, this value equals the process ID (see PID) of the first member of the session, called the session leader, which is usually the login shell.
- STARTED -- Start Time Interval
- The length of time since system boot when a process started. Thus, the most recently started task will display the largest time interval. The value will be expressed as 'MM:SS' (minutes:seconds). But if the interval is too great to fit column width it will be scaled as 'HH,MM' (hours,minutes) and possibly beyond.
- SUID -- Saved User Id
- The saved user ID.
- SUPGIDS -- Supplementary Group IDs
- The IDs of any supplementary group(s) established at login or inherited from a task's parent. They are displayed in a comma delimited list. Note: The SUPGIDS field, unlike most columns, is not fixed-width. When displayed, it plus any other variable width columns will be allocated all remaining screen width (up to the maximum 512 characters).
- SUPGRPS -- Supplementary Group Names
- The names of any supplementary group(s) established at login or inherited from a task's parent. They are displayed in a comma delimited list. Note: The SUPGRPS field, unlike most columns, is not fixed-width. When displayed, it plus any other variable width columns will be allocated all remaining screen width (up to the maximum 512 characters).
- SUSER -- Saved User Name
- The saved user name.
- SWAP -- Swapped Size (KiB)
- The formerly resident portion of a task's address space written to the swap file when physical memory becomes over committed. See `OVERVIEW, Linux Memory Types' for additional details.
- TGID -- Thread Group Id
- The ID of the thread group to which a task belongs. It is the PID of the thread group leader. In kernel terms, it represents those tasks that share an mm_struct.
- TIME -- CPU Time
- Total CPU time the task has used since it started. When Cumulative mode is On, each process is listed with the cpu time that it and its dead children have used. You toggle Cumulative mode with `S', which is both a command-line option and an interactive command. See the `S' interactive command for additional information regarding this mode.
- TIME+ -- CPU Time, hundredths
- The same as TIME, but reflecting more granularity through hundredths of a second.
- TPGID -- Tty Process Group Id
- The process group ID of the foreground process for the connected tty, or -1 if a process is not connected to a terminal. By convention, this value equals the process ID (see PID) of the process group leader (see PGRP).
- TTY -- Controlling Tty
- The name of the controlling terminal. This is usually the device (serial port, pty, etc.) from which the process was started, and which it uses for input or output. However, a task need not be associated with a terminal, in which case you'll see `?' displayed.
- UID -- User Id
- The effective user ID of the task's owner.
- USED -- Memory in Use (KiB)
- This field represents the non-swapped physical memory a task is using (RES) plus the swapped out portion of its address space (SWAP). See `OVERVIEW, Linux Memory Types' for additional details.
- USER -- User Name
- The effective user name of the task's owner.
- USS -- Unique Set Size
- The non-swapped portion of physical memory (`RSS') not shared with any other process. It is derived from the `smaps_rollup' file. Accessing smaps values is 10x more costly than other memory statistics and data for other users requires root privileges.
- VIRT -- Virtual Memory Size (KiB)
- The total amount of virtual memory used by the task. It includes all code, data and shared libraries plus pages that have been swapped out and pages that have been mapped but not used. See `OVERVIEW, Linux Memory Types' for additional details.
- WCHAN -- Sleeping in Function
- This field will show the name of the kernel function in which the task is currently sleeping. Running tasks will display a dash (`-') in this column.
- ioR -- I/O Bytes Read
- The number of bytes a process caused to be fetched from the storage layer. Root privileges are required to display `io' data for other users.
- ioRop -- I/O Read Operations
- The number of read I/O operations (syscalls) for a process. Such calls might not result in actual physical disk I/O.
- ioW -- I/O Bytes Written
- The number of bytes a process caused to be sent to the storage layer.
- ioWop -- I/O Write Operations
- The number of write I/O operations (syscalls) for a process. Such calls might not result in actual physical disk I/O.
- nDRT -- Dirty Pages Count
- The number of pages that have been modified since they were last written to auxiliary storage. Dirty pages must be written to auxiliary storage before the corresponding physical memory location can be used for some other virtual page. This field was deprecated with linux 2.6 and is always zero.
- nMaj -- Major Page Fault Count
- The number of major page faults that have occurred for a task. A page fault occurs when a process attempts to read from or write to a virtual page that is not currently present in its address space. A major page fault is when auxiliary storage access is involved in making that page available.
- nMin -- Minor Page Fault count
- The number of minor page faults that have occurred for a task. A page fault occurs when a process attempts to read from or write to a virtual page that is not currently present in its address space. A minor page fault does not involve auxiliary storage access in making that page available.
- nTH -- Number of Threads
- The number of threads associated with a process.
- nsCGROUP -- CGROUP namespace
- The Inode of the namespace used to hide the identity of the control group of which process is a member.
- nsIPC -- IPC namespace
- The Inode of the namespace used to isolate interprocess communication (IPC) resources such as System V IPC objects and POSIX message queues.
- nsMNT -- MNT namespace
- The Inode of the namespace used to isolate filesystem mount points thus offering different views of the filesystem hierarchy.
- nsNET -- NET namespace
- The Inode of the namespace used to isolate resources such as network devices, IP addresses, IP routing, port numbers, etc.
- nsPID -- PID namespace
- The Inode of the namespace used to isolate process ID numbers meaning they need not remain unique. Thus, each such namespace could have its own `init/systemd' (PID #1) to manage various initialization tasks and reap orphaned child processes.
- nsTIME -- TIME namespace
- The Inode of the namespace which allows processes to see different system times in a way similar to the UTS namespace.
- nsUSER -- USER namespace
- The Inode of the namespace used to isolate the user and group ID numbers. Thus, a process could have a normal unprivileged user ID outside a user namespace while having a user ID of 0, with full root privileges, inside that namespace.
- nsUTS -- UTS namespace
- The Inode of the namespace used to isolate hostname and NIS domain name. UTS simply means "UNIX Time-sharing System".
- vMj -- Major Page Fault Count Delta
- The number of major page faults that have occurred since the last update (see nMaj).
- vMn -- Minor Page Fault Count Delta
- The number of minor page faults that have occurred since the last update (see nMin).
3b. MANAGING Fields
After pressing the interactive command `f' (Fields Management) you will be presented with a screen showing: 1) the `current' window name; 2) the designated sort field; 3) all fields in their current order along with descriptions. Entries marked with an asterisk are the currently displayed fields, screen width permitting.- •
- As the on screen instructions indicate, you navigate among the fields with the Up and Down arrow keys. The PgUp, PgDn, Home and End keys can also be used to quickly reach the first or last available field.
- •
- The Right arrow key selects a field for repositioning and the Left arrow key or the <Enter> key commits that field's placement.
- •
- The `d' key or the <Space> bar toggles a field's display status, and thus the presence or absence of the asterisk.
- •
- The `s' key designates a field as the sort field. See topic 4c. TASK AREA Commands, SORTING for additional information regarding your selection of a sort field.
- •
- The `a' and `w' keys can be used to cycle through all available windows and the ` q' or <Esc> keys exit Fields Management.
4. INTERACTIVE Commands
Listed below is a brief index of commands within categories. Some commands appear more than once -- their meaning or scope may vary depending on the context in which they are issued.4a. Global-Commands <Ent/Sp> ?, =, 0, A, B, d, E, e, g, H, h, I, k, q, r, s, W, X, Y, Z, ^G, ^K, ^N, ^P, ^U, ^L, ^R 4b. Summary-Area-Commands C, l, t, m, 1, 2, 3, 4, 5, ! 4c. Task-Area-Commands Appearance: b, J, j, x, y, z Content: c, F, f, O, o, S, U, u, V, v, ^E Size: #, i, n Sorting: <, >, f, R 4d. Color-Mapping <Ret>, a, B, b, H, M, q, S, T, w, z, 0 - 7 5b. Commands-for-Windows -, _, =, +, A, a, G, g, w 5c. Scrolling-a-Window C, Up, Dn, Left, Right, PgUp, PgDn, Home, End 5d. Searching-in-a-Window L, & 5e. Filtering-in-a-Window O, o, ^O, =, +
4a. GLOBAL Commands
The global interactive commands are always available in both full-screen mode and alternate-display mode. However, some of these interactive commands are not available when running in Secure mode.- <Enter> or <Space> : Refresh-Display
- These commands awaken top and following receipt of any input the entire display will be repainted. They also force an update of any hotplugged cpu or physical memory changes. Use either of these keys if you have a large delay interval and wish to see current status,
- ? | h : Help
- There are two help levels available. The first will provide a reminder of all the basic interactive commands. If top is secured, that screen will be abbreviated. Typing `h' or `?' on that help screen will take you to help for those interactive commands applicable to alternate-display mode.
- = :Exit-Display-Limits
- Removes restrictions on what is shown. This command will reverse any `i' (idle tasks), `n' (max tasks), `v' (hide children) and `F' focus commands that might be active. It also provides for an exit from PID monitoring, User filtering, Other filtering, Locate processing and Combine Cpus mode. Additionally, if the window has been scrolled it will be reset with this command.
- 0 :Zero-Suppress toggle
- This command determines whether zeros are shown or suppressed for many of the fields in a task window. Fields like UID, GID, NI, PR or P are not affected by this toggle.
- A :Alternate-Display-Mode toggle
- This command will switch between full-screen mode and alternate-display mode. See topic 5. ALTERNATE-DISPLAY Provisions and the `g' interactive command for insight into `current' windows and field groups.
- B :Bold-Disable/Enable toggle
- This command will influence use of the bold terminfo capability and alters both the summary area and task area for the `current' window. While it is intended primarily for use with dumb terminals, it can be applied anytime. Note: When this toggle is On and top is operating in monochrome mode, the entire display will appear as normal text. Thus, unless the `x' and/or `y' toggles are using reverse for emphasis, there will be no visual confirmation that they are even on.
- * d | s :Change-Delay-Time-interval
- You will be prompted to enter the delay time, in seconds, between display updates. Fractional seconds are honored, but a negative number is not allowed. Entering 0 causes (nearly) continuous updates, with an unsatisfactory display as the system and tty driver try to keep up with top's demands. The delay value is inversely proportional to system loading, so set it with care. If at any time you wish to know the current delay time, simply ask for help and view the system summary on the second line.
- E :Enforce-Summary-Memory-Scale in Summary Area
- With this command you can cycle through the available summary area memory scaling which ranges from KiB (kibibytes or 1,024 bytes) through EiB (exbibytes or 1,152,921,504,606,846,976 bytes). If you see a `+' between a displayed number and the following label, it means that top was forced to truncate some portion of that number. By raising the scaling factor, such truncation can be avoided.
- e :Enforce-Task-Memory-Scale in Task Area
- With this command you can cycle through the available task area memory scaling which ranges from KiB (kibibytes or 1,024 bytes) through PiB (pebibytes or 1,125,899,906,842,624 bytes). While top will try to honor the selected target range, additional scaling might still be necessary in order to accommodate current values. If you wish to see a more homogeneous result in the memory columns, raising the scaling range will usually accomplish that goal. Raising it too high, however, is likely to produce an all zero result which cannot be suppressed with the `0' interactive command.
- g :Choose-Another-Window/Field-Group
- You will be prompted to enter a number between 1 and 4 designating the field group which should be made the `current' window. You will soon grow comfortable with these 4 windows, especially after experimenting with alternate-display mode.
- H :Threads-mode toggle
- When this toggle is On, individual threads will be displayed for all processes in all visible task windows. Otherwise, top displays a summation of all threads in each process.
- I :Irix/Solaris-Mode toggle
- When operating in Solaris mode (`I' toggled Off), a task's cpu usage will be divided by the total number of CPUs. After issuing this command, you'll be told the new state of this toggle.
- * k :Kill-a-task
- You will be prompted for a PID and then the signal to send.
Entering no PID or a negative number will be interpreted as the default
shown in the prompt (the first task displayed). A PID value of zero means
the top program itself.
The default signal, as reflected in the prompt, is SIGTERM. However, you can
send any signal, via number or name.
If you wish to abort the kill process, do one of the following depending on
your progress:
1) at the pid prompt, type an invalid number 2) at the signal prompt, type 0 (or any invalid signal) 3) at any prompt, type <Esc>
- q :Quit
- * r :Renice-a-Task
- You will be prompted for a PID and then the value to nice
it to.
Entering no PID or a negative number will be interpreted as the default
shown in the prompt (the first task displayed). A PID value of zero means
the top program itself.
A positive nice value will cause a process to lose priority. Conversely, a
negative nice value will cause a process to be viewed more favorably by
the kernel. As a general rule, ordinary users can only increase the nice
value and are prevented from lowering it.
If you wish to abort the renice process, do one of the following depending
on your progress:
1) at the pid prompt, type an invalid number 2) at the nice prompt, type <Enter> with no input 3) at any prompt, type <Esc>
- W :Write-the-Configuration-File
- This will save all of your options and toggles plus the current display mode and delay time. By issuing this command just before quitting top, you will be able restart later in exactly that same state.
- X :Extra-Fixed-Width
- Some fields are fixed width and not scalable. As such, they
are subject to truncation which would be indicated by a `+' in the last
position.
This interactive command can be used to alter the widths of the following
fields:
field default field default field default GID 5 GROUP 8 WCHAN 10 LOGID 5 LXC 8 nsCGROUP 10 RUID 5 RUSER 8 nsIPC 10 SUID 5 SUSER 8 nsMNT 10 UID 5 TTY 8 nsNET 10 USER 8 nsPID 10 nsTIME 10 nsUSER 10 nsUTS 10
You will be prompted for the amount to be added to the default widths shown above. Entering zero forces a return to those defaults. If you enter a negative number, top will automatically increase the column size as needed until there is no more truncated data. Note: Whether explicitly or automatically increased, the widths for these fields are never decreased by top. To narrow them you must specify a smaller number or restore the defaults.
- Y :Inspect-Other-Output
- After issuing the `Y' interactive command, you will be
prompted for a target PID. Typing a value or accepting the default results
in a separate screen. That screen can be used to view a variety of files
or piped command output while the normal top iterative display is paused.
Note: This interactive command is only fully realized when
supporting entries have been manually added to the end of the top
configuration file. For details on creating those entries, see topic 6b.
ADDING INSPECT Entries.
Most of the keys used to navigate the Inspect feature are reflected in its
header prologue. There are, however, additional keys available once you
have selected a particular file or command. They are familiar to anyone
who has used the pager `less' and are summarized here for future
reference.
key function = alternate status-line, file or pipeline / find, equivalent to `L' locate n find next, equivalent to `&' locate next <Space> scroll down, equivalent to <PgDn> b scroll up, equivalent to <PgUp> g first line, equivalent to <Home> G last line, equivalent to <End>
- Z :Change-Color-Mapping
- This key will take you to a separate screen where you can change the colors for the `current' window, or for all windows. For details regarding this interactive command see topic 4d. COLOR Mapping.
Applied to the first process displayed, these
commands will show that task's full (potentially wrapped) information. Such
data will be displayed in a separate window at the bottom of the screen while
normal top monitoring continues.
Keying the same `Ctrl' command a second time removes that separate
window as does the `=' command. Keying a different `Ctrl' combination, while
one is already active, immediately transitions to the new information.
Notable among these provisions is the Ctrl+N (environment) command. Its output
can be extensive and not easily read when line wrapped. A more readable
version can be achieved with an `Inspect' entry in the rcfile like the
following.
See the `Y' interactive command above and topic 6b. ADDING INSPECT Entries for
additional information.
As an alternative to `Inspect', and available to all of these `Ctrl' commands,
the tab key can be used to highlight individual elements in the bottom window.
pipe ^I Environment ^I cat /proc/%d/environ | tr '\0' '\n'
- ^L :Logged-Messages (Ctrl key + `l')
- The 10 most recent messages are displayed in a separate window at the bottom of the screen while normal top monitoring continues. Keying `^L' a second time removes that window as does the `=' command. Use the tab key to highlight individual messages.
- * ^R :Renice-an-Autogroup (Ctrl key + `r')
- You will be prompted for a PID and then the value for its autogroup AGNI. Entering no PID will be interpreted as the default shown in the prompt (the first task displayed). A positive AGNI value will cause processes in that autogroup to lose priority. Conversely, a negative value causes them to be viewed more favorably by the kernel. Ordinary users are not allowed to set negative AGNI values. If you wish to abort the renice process type <Esc>.
- *
- The commands shown with an asterisk (`*') are not available in Secure mode, nor will they be shown on the level-1 help screen.
4b. SUMMARY AREA Commands
The summary area interactive commands are always available in both full-screen mode and alternate-display mode. They affect the beginning lines of your display and will determine the position of messages and prompts.- C :Show-scroll-coordinates toggle
- Toggle an informational message which is displayed whenever the message line is not otherwise being used. For additional information see topic 5c. SCROLLING a Window.
- l :Load-Average/Uptime toggle
- This is also the line containing the program name (possibly an alias) when operating in full-screen mode or the `current' window name when operating in alternate-display mode.
- t :Task/Cpu-States toggle
- This command affects from 2 to many summary area lines,
depending on the state of the `1', `2' or `3' command toggles and whether
or not top is running under true SMP.
This portion of the summary area is also influenced by the `H' interactive
command toggle, as reflected in the total label which shows either Tasks
or Threads.
This command serves as a 4-way toggle, cycling through these modes:
1. detailed percentages by category 2. abbreviated user/system and total % + bar graph 3. abbreviated user/system and total % + block graph 4. turn off task and cpu states display
When operating in either of the graphic modes, the display becomes much more meaningful when individual CPUs or NUMA nodes are also displayed. See the the `1', `2' and `3' commands below for additional information.
- m :Memory/Swap-Usage toggle
- This command affects the two summary area lines dealing
with physical and virtual memory.
This command serves as a 4-way toggle, cycling through these modes:
1. detailed percentages by memory type 2. abbreviated % used/total available + bar graph 3. abbreviated % used/total available + block graph 4. turn off memory display
- 1 :Single/Separate-Cpu-States toggle
- This command affects how the `t' command's Cpu States portion is shown. Although this toggle exists primarily to serve massively-parallel SMP machines, it is not restricted to solely SMP environments. When you see `%Cpu(s):' in the summary area, the `1' toggle is On and all cpu information is gathered in a single line. Otherwise, each cpu is displayed separately as: `%Cpu0, %Cpu1, ...' up to available screen height.
- 2 :NUMA-Nodes/Cpu-Summary toggle
- This command toggles between the `1' command cpu summary display (only) or a summary display plus the cpu usage statistics for each NUMA Node. It is only available if a system has the requisite NUMA support.
- 3 :Expand-NUMA-Node
- You will be invited to enter a number representing a NUMA Node. Thereafter, a node summary plus the statistics for each cpu in that node will be shown until the `1', `2' or `4' command toggle is pressed. This interactive command is only available if a system has the requisite NUMA support.
- 4 :Display-Multiple-Elements-Adjacent toggle
- This command toggle turns the `1' toggle Off and shows multiple CPU and Memory results on each line. Each successive `4' key adds another CPU until again reverting to separate lines for CPU and Memory results. A maximum of 8 CPUs per line can be displayed in this manner. However, data truncation may occur before reaching the maximum. That is definitely true when displaying detailed statistics via the `t' command toggle since such data cannot be scaled like the graphic representations. If one wished to quickly exit adjacent mode without cycling all the way to 8, simply use the `1' command toggle.
- 5 :Display-P-Cores-and-E-Cores toggle
- This command toggle is only active when the `t' toggle is On and the `1', `2', `3' and `!' toggles are Off, thus showing individual CPU results. It assumes a platform has multiple cores of two distinct types, either multi-threaded (P-Core) or single-threaded (E-Core). While normally each cpu is displayed as `%Cpu0, %Cpu1, ...', this toggle can be used to identify and/or filter those cpus by their core type, either P-Core (performance) or E-Core (efficient). The 1st time `5' is struck, each CPU is displayed as `%Cp P' or `%Cp E' representing the two core types. The 2nd time, only P-Cores (%Cp P) will be shown. The 3rd time, only E-Cores (%Cp E) are displayed. When this command toggle is struck for the 4th time, the CPU display returns to the normal `%Cpu' convention. If separate performance and efficient categories are not present, this command toggle will have no effect.
- ! :Combine-Cpus-Mode toggle
- This command toggle is intended for massively parallel SMP environments where, even with the `4' command toggle, not all processors can be displayed. With each press of `!' the number of additional cpus combined is doubled thus reducing the total number of cpu lines displayed. For example, with the first press of `!' one additional cpu will be combined and displayed as `0-1, 2-3, ...' instead of the normal `%Cpu0, %Cpu1, %Cpu2, %Cpu3, ...'. With a second `!' command toggle two additional cpus are combined and shown as `0-2, 3-5, ...'. Then the third '!' press, combining four additional cpus, shows as `0-4, 5-9, ...', etc. Such progression continues until individual cpus are again displayed and impacts both the `1' and `4' toggles (one or muliple columns). Use the `=' command to exit Combine Cpus mode.
4c. TASK AREA Commands
The task area interactive commands are always available in full-screen mode.- J :Justify-Numeric-Columns toggle
- Alternates between right-justified (the default) and left-justified numeric data. If the numeric data completely fills the available column, this command toggle may impact the column header only.
- j :Justify-Character-Columns toggle
- Alternates between left-justified (the default) and right-justified character data. If the character data completely fills the available column, this command toggle may impact the column header only.
The following commands will also be influenced
by the state of the global `B' (bold enable) toggle.
- b :Bold/Reverse toggle
- This command will impact how the `x' and `y' toggles are displayed. It may also impact the summary area when a bar graph has been selected for cpu states or memory usage via the `t' or `m' toggles.
- x :Column-Highlight toggle
- Changes highlighting for the current sort field. If you
forget which field is being sorted this command can serve as a quick
visual reminder, providing the sort field is being displayed. The sort
field might not be visible because:
1) there is insufficient Screen Width
2) the `f' interactive command turned it Off
- y :Row-Highlight toggle
- Changes highlighting for "running" tasks. For additional insight into this task state, see topic 3a. DESCRIPTIONS of Fields, the `S' field (Process Status). Use of this provision provides important insight into your system's health. The only costs will be a few additional tty escape sequences.
- z :Color/Monochrome toggle
- Switches the `current' window between your last used color scheme and the older form of black-on-white or white-on-black. This command will alter both the summary area and task area but does not affect the state of the `x', `y' or `b' toggles.
- c :Command-Line/Program-Name toggle
- This command will be honored whether or not the COMMAND column is currently visible. Later, should that field come into view, the change you applied will be seen.
- F :Maintain-Parent-Focus toggle
- When in forest view mode, this key serves as a toggle to retain focus on a target task, presumably one with forked children. If forest view mode is Off this key has no effect. The toggle is applied to the first (topmost) process in the `current' window. Once established, that task is always displayed as the first (topmost) process along with its forked children. All other processes will be suppressed. Note: keys like `i' (idle tasks), `n' (max tasks), `v' (hide children) and User/Other filtering remain accessible and can impact what is displayed.
- f :Fields-Management
- This key displays a separate screen where you can change which fields are displayed, their order and also designate the sort field. For additional information on this interactive command see topic 3b. MANAGING Fields.
- O | o : Other-Filtering
- You will be prompted for the selection criteria which then determines which tasks will be shown in the `current' window. Your criteria can be made case sensitive or case can be ignored. And you determine if top should include or exclude matching tasks. See topic 5e. FILTERING in a window for details on these and additional related interactive commands.
- S :Cumulative-Time-Mode toggle
- When Cumulative mode is On, each process is listed with the cpu time that it and its dead children have used. When Off, programs that fork into many separate tasks will appear less demanding. For programs like `init' or a shell this is appropriate but for others, like compilers, perhaps not. Experiment with two task windows sharing the same sort field but with different `S' states and see which representation you prefer. After issuing this command, you'll be informed of the new state of this toggle. If you wish to know in advance whether or not Cumulative mode is in effect, simply ask for help and view the window summary on the second line.
- U | u : Show-Specific-User-Only
- You will be prompted for the uid or name of the user to display. The -u option matches on effective user whereas the -U option matches on any user (real, effective, saved, or filesystem). Thereafter, in that task window only matching users will be shown, or possibly no processes will be shown. Prepending an exclamation point (`!') to the user id or name instructs top to display only processes with users not matching the one provided. Different task windows can be used to filter different users. Later, if you wish to monitor all users again in the `current' window, re-issue this command but just press <Enter> at the prompt.
- V :Forest-View-Mode toggle
- In this mode, processes are reordered according to their parents and the layout of the COMMAND column resembles that of a tree. In forest view mode it is still possible to toggle between program name and command line (see the `c' interactive command) or between processes and threads (see the `H' interactive command). Note: Typing any key affecting the sort order will exit forest view mode in the `current' window. See topic 4c. TASK AREA Commands, SORTING for information on those keys.
- v :Hide/Show-Children toggle
- When in forest view mode, this key serves as a toggle to collapse or expand the children of a parent. The toggle is applied against the first (topmost) process in the `current' window. See topic 5c. SCROLLING a Window for additional information regarding vertical scrolling. If the target process has not forked any children, this key has no effect. It also has no effect when not in forest view mode.
- ^E :Scale-CPU-Time-fields (Ctrl key + `e')
- The `time' fields are normally displayed with the greatest precision their widths permit. This toggle reduces that precision until it wraps. It also illustrates the scaling those fields might experience automatically, which usually depends on how long the system runs. For example, if 'MMM:SS.hh' is shown, each ^E keystroke would change it to: 'MM:SS', 'Hours,MM', 'Days+Hours' and finally 'Weeks+Days'. Not all time fields are subject to the full range of such scaling.
- i :Idle-Process toggle
- Displays all tasks or just active tasks. When this toggle is Off, tasks that have not used any CPU since the last update will not be displayed. However, due to the granularity of the %CPU and TIME+ fields, some processes may still be displayed that appear to have used no CPU. If this command is applied to the last task display when in alternate-display mode, then it will not affect the window's size, as all prior task displays will have already been painted.
- n | # : Set-Maximum-Tasks
- You will be prompted to enter the number of tasks to display. The lessor of your number and available screen rows will be used. When used in alternate-display mode, this is the command that gives you precise control over the size of each currently visible task display, except for the very last. It will not affect the last window's size, as all prior task displays will have already been painted. Note: If you wish to increase the size of the last visible task display when in alternate-display mode, simply decrease the size of the task display(s) above it.
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.
Before using any of the following sort provisions, top suggests that you
temporarily turn on column highlighting using the `x' interactive command.
That will help ensure that the actual sort environment matches your intent.
The following interactive commands will only be honored when the current
sort field is visible. The sort field might not be visible
because:
1) there is insufficient Screen Width
2) the `f' interactive command turned it Off
command sorted-field supported A start time (non-display) No M %MEM Yes N PID Yes P %CPU Yes T TIME+ Yes
1) there is insufficient Screen Width
2) the `f' interactive command turned it Off
- < :Move-Sort-Field-Left
- Moves the sort column to the left unless the current sort field is the first field being displayed.
- > :Move-Sort-Field-Right
- Moves the sort column to the right unless the current sort field is the last field being displayed.
- f :Fields-Management
- This key displays a separate screen where you can change which field is used as the sort column, among other functions. This can be a convenient way to simply verify the current sort field, when running top with column highlighting turned Off.
- R :Reverse/Normal-Sort-Field toggle
- Using this interactive command you can alternate between high-to-low and low-to-high sorts.
4d. COLOR Mapping
When you issue the `Z' interactive command, you will be presented with a separate screen. That screen can be used to change the colors in just the `current' window or in all four windows before returning to the top display.4 upper case letters to select a target 8 numbers to select a color normal toggles available B :bold disable/enable b :running tasks "bold"/reverse z :color/mono other commands available a/w :apply, then go to next/prior <Enter> :apply and exit q :abandon current changes and exit
5. ALTERNATE-DISPLAY Provisions
5a. WINDOWS Overview
- Field Groups/Windows:
- In full-screen mode there is a single window represented by the entire screen. That single window can still be changed to display 1 of 4 different field groups (see the `g' interactive command, repeated below). Each of the 4 field groups has a unique separately configurable summary area and its own configurable task area. In alternate-display mode, those 4 underlying field groups can now be made visible simultaneously, or can be turned Off individually at your command. The summary area will always exist, even if it's only the message line. At any given time only one summary area can be displayed. However, depending on your commands, there could be from zero to four separate task displays currently showing on the screen.
- Current Window:
- The `current' window is the window associated with the summary area and the window to which task related commands are always directed. Since in alternate-display mode you can toggle the task display Off, some commands might be restricted for the `current' window. A further complication arises when you have toggled the first summary area line Off. With the loss of the window name (the `l' toggled line), you'll not easily know what window is the `current' window.
5b. COMMANDS for Windows
- - | _ : Show/Hide-Window(s) toggles
- The `-' key turns the `current' window's task display On and Off. When On, that task area will show a minimum of the columns header you've established with the `f' interactive command. It will also reflect any other task area options/toggles you've applied yielding zero or more tasks. The `_' key does the same for all task displays. In other words, it switches between the currently visible task display(s) and any task display(s) you had toggled Off. If all 4 task displays are currently visible, this interactive command will leave the summary area as the only display element.
- * = | + :Equalize/Reset-Window(s)
- The `=' key forces the `current' window's task display to be visible. It also reverses any active `i' (idle tasks), `n' (max tasks), `u/U' (user filter), `o/O' (other filter), `v' (hide children), `F' focused, `L' (locate) and `!' (combine cpus) commands. Also, if the window had been scrolled, it will be reset with this command. See topic 5c. SCROLLING a Window for additional information regarding vertical and horizontal scrolling. The `+' key does the same for all windows. The four task displays will reappear, evenly balanced, while retaining any customizations previously applied beyond those noted for the `=' command toggle.
- * A :Alternate-Display-Mode toggle
- This command will switch between full-screen mode and alternate-display mode. The first time you issue this command, all four task displays will be shown. Thereafter when you switch modes, you will see only the task display(s) you've chosen to make visible.
- * a | w :Next-Window-Forward/Backward
- This will change the `current' window, which in turn changes the window to which commands are directed. These keys act in a circular fashion so you can reach any desired window using either key. Assuming the window name is visible (you have not toggled `l' Off), whenever the `current' window name loses its emphasis/color, that's a reminder the task display is Off and many commands will be restricted.
- G :Change-Window/Field-Group-Name
- You will be prompted for a new name to be applied to the `current' window. It does not require that the window name be visible (the `l' toggle to be On).
- *
- The interactive commands shown with an asterisk (`*') have
use beyond alternate-display mode.
=, A, g are always available a, w act the same with color mapping and fields management
- * g :Choose-Another-Window/Field-Group
- You will be prompted to enter a number between 1 and 4 designating the field group which should be made the `current' window. In full-screen mode, this command is necessary to alter the `current' window. In alternate-display mode, it is simply a less convenient alternative to the `a' and `w' commands.
5c. SCROLLING a Window
Typically a task window is a partial view into a system's total tasks/threads which shows only some of the available fields/columns. With these scrolling keys, you can move that view vertically or horizontally to reveal any desired task or column.- Up,PgUp :Scroll-Tasks
- Move the view up toward the first task row, until the first task is displayed at the top of the `current' window. The Up arrow key moves a single line while PgUp scrolls the entire window.
- Down,PgDn :Scroll-Tasks
- Move the view down toward the last task row, until the last task is the only task displayed at the top of the `current' window. The Down arrow key moves a single line while PgDn scrolls the entire window.
- Left,Right :Scroll-Columns
- Move the view of displayable fields horizontally one column at a time. Note: As a reminder, some fields/columns are not fixed-width but allocated all remaining screen width when visible. When scrolling right or left, that feature may produce some unexpected results initially. Additionally, there are special provisions for any variable width field when positioned as the last displayed field. Once that field is reached via the right arrow key, and is thus the only column shown, you can continue scrolling horizontally within such a field. See the `C' interactive command below for additional information.
- Home :Jump-to-Home-Position
- Reposition the display to the un-scrolled coordinates.
- End :Jump-to-End-Position
- Reposition the display so that the rightmost column reflects the last displayable field and the bottom task row represents the last task. Note: From this position it is still possible to scroll down and right using the arrow keys. This is true until a single column and a single task is left as the only display element.
- C :Show-scroll-coordinates toggle
- Toggle an informational message which is displayed whenever
the message line is not otherwise being used. That message will take one
of two forms depending on whether or not a variable width column has also
been scrolled.
scroll coordinates: y = n/n (tasks), x = n/n (fields) scroll coordinates: y = n/n (tasks), x = n/n (fields) + nn
The coordinates shown as n/n are relative to the upper left corner of the `current' window. The additional ` + nn' represents the displacement into a variable width column when it has been scrolled horizontally. Such displacement occurs in normal 8 character tab stop amounts via the right and left arrow keys.
- y = n/n (tasks)
- The first n represents the topmost visible task and is controlled by scrolling keys. The second n is updated automatically to reflect total tasks.
- x = n/n (fields)
- The first n represents the leftmost displayed column and is controlled by scrolling keys. The second n is the total number of displayable fields and is established with the ` f' interactive command.
5d. SEARCHING in a Window
You can use these interactive commands to locate a task row containing a particular value.- L :Locate-a-string
- You will be prompted for the case-sensitive string to locate starting from the current window coordinates. There are no restrictions on search string content. Searches are not limited to values from a single field or column. All of the values displayed in a task row are allowed in a search string. You may include spaces, numbers, symbols and even forest view artwork. Keying <Enter> with no input will effectively disable the `&' key until a new search string is entered.
- & :Locate-next
- Assuming a search string has been established, top will attempt to locate the next occurrence.
- a. Which fields are displayable from the total available,
- see topic 3b. MANAGING Fields.
- b. Scrolling a window vertically and/or horizontally,
- see topic 5c. SCROLLING a Window.
- c. The state of the command/command-line toggle,
- see the `c' interactive command.
- d. The stability of the chosen sort column,
- for example PID is good but %CPU bad.
5e. FILTERING in a Window
You can use this `Other Filter' feature to establish selection criteria which will then determine which tasks are shown in the `current' window. Such filters can be made persistent if preserved in the rcfile via the 'W' interactive command.- 1. field names are case sensitive and spelled as in the header
- 2. selection values need not comprise the full displayed field
- 3. a selection is either case insensitive or sensitive to case
- 4. the default is inclusion, prepending `!' denotes exclusions
- 5. multiple selection criteria can be applied to a task window
- 6. inclusion and exclusion criteria can be used simultaneously
- 7. the 1 equality and 2 relational filters can be freely mixed
- 8. separate unique filters are maintained for each task window
- O :Other-Filter (upper case)
- You will be prompted to establish a case sensitive filter.
- o :Other-Filter (lower case)
- You will be prompted to establish a filter that ignores case when matching.
- ^O :Show-Active-Filters (Ctrl key + `o')
- This can serve as a reminder of which filters are active in the `current' window. A summary will be shown on the message line until you press the <Enter> key.
- = :Reset-Filtering in current window
- This clears all of your selection criteria in the `current' window. It also has additional impact so please see topic 4a. GLOBAL Commands.
- + :Reset-Filtering in all windows
- This clears the selection criteria in all windows, assuming you are in alternate-display mode. As with the `=' interactive command, it too has additional consequences so you might wish to see topic 5b. COMMANDS for Windows.
When prompted for selection criteria, the data you provide must take one of two
forms. There are 3 required pieces of information, with a 4th as optional.
These examples use spaces for clarity but your input generally would not.
Items #1, #3 and #4 should be self-explanatory. Item #2 represents both a
required delimiter and the operator which must be one of either
equality (`=') or relation (`<' or `>').
The `=' equality operator requires only a partial match and that can reduce your
`if-value' input requirements. The `>' or `<' relational operators
always employ string comparisons, even with numeric fields. They are designed
to work with a field's default justification and with homogeneous data.
When some field's numeric amounts have been subjected to scaling while
others have not, that data is no longer homogeneous.
If you establish a relational filter and you have changed the default
Numeric or Character justification, that filter is likely to fail. When
a relational filter is applied to a memory field and you have not
changed the scaling, it may produce misleading results. This happens,
for example, because `100.0m' (MiB) would appear greater than `1.000g' (GiB)
when compared as strings.
If your filtered results appear suspect, simply altering justification or
scaling may yet achieve the desired objective. See the `j', `J' and `e'
interactive commands for additional information.
#1 #2 #3 ( required ) Field-Name ? include-if-value ! Field-Name ? exclude-if-value #4 ( optional )
These GROUP filters could produce the exact same results or the second
one might not display anything at all, just a blank task window.
Either of these RES filters might yield inconsistent and/or misleading
results, depending on the current memory scaling factor. Or both filters could
produce the exact same results.
This nMin filter illustrates a problem unique to scalable fields. This
particular field can display a maximum of 4 digits, beyond which values are
automatically scaled to KiB or above. So while amounts greater than 9999
exist, they will appear as 2.6m, 197k, etc.
GROUP=root ( only the same results when ) GROUP=ROOT ( invoked via lower case `o' )
RES>9999 ( only the same results when ) !RES<10000 ( memory scaling is at `KiB' )
nMin>9999 ( always a blank task window )
These examples illustrate how Other Filtering can be creatively applied to
achieve almost any desired result. Single quotes are sometimes shown to
delimit the spaces which are part of a filter or to represent a request for
status (^O) accurately. But if you used them with if-values in real life, no
matches would be found.
Assuming field nTH is displayed, the first filter will result in only
multi-threaded processes being shown. It also reminds us that a trailing space
is part of every displayed field. The second filter achieves the exact same
results with less typing.
With Forest View mode active and the COMMAND column in view, this filter
effectively collapses child processes so that just 3 levels are shown.
The final two filters appear as in response to the status request key (^O). In
reality, each filter would have required separate input. The PR example
shows the two concurrent filters necessary to display tasks with priorities of
20 or more, since some might be negative. Then by exploiting trailing spaces,
the nMin series of filters could achieve the failed `9999' objective
discussed above.
!nTH=` 1 ' ( ' for clarity only ) nTH>1 ( same with less i/p )
!COMMAND=` `- ' ( ' for clarity only )
`PR>20' + `!PR=-' ( 2 for right result ) `!nMin=0 ' + `!nMin=1 ' + `!nMin=2 ' + `!nMin=3 ' ...
6. FILES
6a. PERSONAL Configuration File
This file is created or updated via the 'W' interactive command.global # line 1: the program name/alias notation " # line 2: id,altscr,irixps,delay,curwin per ea # line a: winname,fieldscur window # line b: winflags,sortindx,maxtasks,etc " # line c: summclr,msgsclr,headclr,taskclr global # line 15: additional miscellaneous settings " # any remaining lines are devoted to optional " # active 'other filters' discussed in section 5e above " # plus 'inspect' entries discussed in section 6b below
6b. ADDING INSPECT Entries
To exploit the `Y' interactive command, you must add entries at the end of the top personal configuration file. Such entries simply reflect a file to be read or command/pipeline to be executed whose results will then be displayed in a separate scrollable, searchable window..type: literal `file' or `pipe' .name: selection shown on the Inspect screen .fmts: string representing a path or command
.fmts= /proc/ %d/numa_maps .fmts= lsof -P -p %d
.fmts= pmap -x %d 2>&1
# pipe ^I Sockets ^I lsof -n -P -i 2>&1 pipe ^I Open Files ^I lsof -P -p %d 2>&1 file ^I NUMA Info ^I /proc/%d/numa_maps pipe ^I Log ^I tail -n100 /var/log/syslog | sort -Mr
"pipe\tOpen Files\tlsof -P -p %d 2>&1" >> ~/.toprc "file\tNUMA Info\t/proc/%d/numa_maps" >> ~/.toprc "pipe\tLog\ttail -n200 /var/log/syslog | sort -Mr" >> ~/.toprc
# next would have contained `\t' ... # file ^I <your_name> ^I /proc/%d/status # but this will eliminate embedded `\t' ... pipe ^I <your_name> ^I cat /proc/%d/status | expand -
pipe ^I Trace ^I /usr/bin/strace -p %d 2>&1
Inspection Pause at pid ... Use: left/right then <Enter> ... Options: help 1 2 3 4 5 6 7 8 9 10 11 ...
6c. SYSTEM Configuration File
This configuration file represents defaults for users who have not saved their own configuration file. The format mirrors exactly the personal configuration file and can also include `inspect' entries as explained above.6d. SYSTEM Restrictions File
The presence of this file will influence which version of the help screen is shown to an ordinary user.k Kill a task r Renice a task d or s Change delay/sleep interval
s # line 1: secure mode switch 5.0 # line 2: delay interval in seconds
7. ENVIRONMENT VARIABLE(S)
The value set for the following is unimportant, just its presence.- LIBPROC_HIDE_KERNEL
- This will prevent display of any kernel threads and exclude such processes from the summary area Tasks/Threads counts.
8. STUPID TRICKS Sampler
Many of these tricks work best when you give top a scheduling boost. So plan on starting him with a nice value of -10, assuming you've got the authority.7a. Kernel Magic
For these stupid tricks, top needs full-screen mode.- •
- The user interface, through prompts and help, intentionally
implies that the delay interval is limited to tenths of a second. However,
you're free to set any desired delay. If you want to see Linux at his
scheduling best, try a delay of .09 seconds or less.
For this experiment, under x-windows open an xterm and maximize it. Then do
the following:
. provide a scheduling boost and tiny delay via: nice -n -10 top -d.09 . keep sorted column highlighting Off so as to minimize path length . turn On reverse row highlighting for emphasis . try various sort columns (TIME/MEM work well), and normal or reverse sorts to bring the most active processes into view
What you'll see is a very busy Linux doing what he's always done for you, but there was no program available to illustrate this.
- •
- Under an xterm using `white-on-black' colors, on top's Color Mapping screen set the task color to black and be sure that task highlighting is set to bold, not reverse. Then set the delay interval to around .3 seconds. After bringing the most active processes into view, what you'll see are the ghostly images of just the currently running tasks.
- •
- Delete the existing rcfile, or create a new symlink. Start this new version then type `T' (a secret key, see topic 4c. Task Area Commands, SORTING) followed by `W' and `q'. Finally, restart the program with -d0 (zero delay). Your display will be refreshed at three times the rate of the former top, a 300% speed advantage. As top climbs the TIME ladder, be as patient as you can while speculating on whether or not top will ever reach the top.
7b. Bouncing Windows
For these stupid tricks, top needs alternate-display mode.- •
- With 3 or 4 task displays visible, pick any window other than the last and turn idle processes Off using the `i' command toggle. Depending on where you applied `i', sometimes several task displays are bouncing and sometimes it's like an accordion, as top tries his best to allocate space.
- •
- Set each window's summary lines differently: one with no memory (`m'); another with no states (`t'); maybe one with nothing at all, just the message line. Then hold down `a' or `w' and watch a variation on bouncing windows -- hopping windows.
- •
- Display all 4 windows and for each, in turn, set idle processes to Off using the `i' command toggle. You've just entered the "extreme bounce" zone.
7c. The Big Bird Window
This stupid trick also requires alternate-display mode.- •
- Display all 4 windows and make sure that 1:Def is the
`current' window. Then, keep increasing window size with the `n'
interactive command until all the other task displays are "pushed out
of the nest".
When they've all been displaced, toggle between all visible/invisible
windows using the `_' command toggle. Then ponder this:
is top fibbing or telling honestly your imposed truth?
7d. The Ol' Switcheroo
This stupid trick works best without alternate-display mode, since justification is active on a per window basis.- •
- Start top and make COMMAND the last (rightmost) column
displayed. If necessary, use the `c' command toggle to display command
lines and ensure that forest view mode is active with the `V' command
toggle.
Then use the up/down arrow keys to position the display so that some
truncated command lines are shown (`+' in last position). You may have to
resize your xterm to produce truncation.
Lastly, use the `j' command toggle to make the COMMAND column right
justified.
Now use the right arrow key to reach the COMMAND column. Continuing with the
right arrow key, watch closely the direction of travel for the command
lines being shown.
some lines travel left, while others travel right
eventually all lines will Switcheroo, and move right
9. BUGS
Please send bug reports to [email protected]10. SEE Also
free(1), ps(1), uptime(1), atop(1), slabtop(1), vmstat(8), w(1)September 2022 | procps-ng |