pcp-htop is a customizable performance metrics reporting tool. It has a dynamic architecture, where a set of configuration files provide additional, optional meters and columns to extend the fixed set of display options provided by regular htop.
These configuration files can be provided from both system-wide locations (first /etc/pcp/htop then /usr/share/pcp/htop) and below the user's home directory (usually ~/.config/htop). Within these locations the meters and columns are scanned for dynamic Meter and Column specifications.
Meters are displayed in the top part of the pcp-htop window, and columns are displayed in the lower part. Meters tend to display system-wide metrics, and Columns display metrics about individual processes.
The formats are similar but have slightly different requirements. Both formats follow the common ini-style. Blank lines are ignored. Lines starting with the "#" character are treated as comments.
The following is an example configuration for a new Redis meter:
[redisclient] caption = Redis clients type = bar blocked.metric = redis.blocked_clients blocked.color = blue blocked.label = blk clients.metric = redis.connected_clients clients.color = green clients.label = conn
A configuration file can contain multiple meter definitions. Each definition begins with a identifying name enclosed by square brackets - redisclient in this example. The name is used internally within pcp-htop and must be unique, must begin with an alphabetic character, and may subsequently only contain alphanumeric characters or the underscore character. No whitespace or other characters are allowed.
There are several parameters that define the way the meter will be displayed to the user.
This value is displayed on the Setup screen once the meter has been selected. A truncated version of the caption will also be displayed (followed by a colon) on the primary display while the meter is updating.
This can be used to provide more detail during the meter selection process on the Setup screen, and if present it is displayed in the "Available Meters" column. If not present, the caption will be used for this. If neither is present, the internal (mandatory) name will be used.
This setting allows a preferred default meter type to be specified. The associated value must be one of bar, text, graph, or led. If no value is provided for a dynamic meter, the default value of text will be used.
A numeric value can also be set to size the meter, such that values (e.g. for a bar type meter display) will be scaled within range zero to maximum.
The remaining definition syntax describes the individual metric(s) which will be used to animate the meter. One or more metrics must be specified for each meter and there are several properties associated with each. Once again, these metrics must be named (the same rules described above for meters apply here) and the following properties can be configured:
This is the only mandatory field and associates a PCP metric with the meter. Values sampled for each metric at runtime provide the animation visible in the pcp-htop display. The metric specification can be either a PCP metric name as listed by pminfo(1) or a "derived" metric expression. The format for derived metric expressions is described on the pmRegisterDerived(3) manual page.
Setting color to be used when rendering metric values. Possible values are red, green, blue, cyan, magenta, yellow, gray, darkgray or white.
An optional, short label to display before the metric value. The ":" character will be appended to the label before the metric value part of the display.
An optional, short suffix to display after the metric value. Commonly used to indicate values as a percentage using a "%" suffix value and to provide the base unit of measurement. Note that since PCP maintains units for metrics, for those metrics that have dimension in "space" (bytes, kilobytes, megabytes, etc), a suffix will be automatically appended.
The following is an example configuration for a new column showing open file descriptors for each process:
[openfds] heading = FDS caption = FDCOUNT description = Open file descriptors metric = proc.fd.count width = 3
A configuration file can contain multiple column definitions. Each definition begins with a identifying name enclosed by square brackets - openfds in this example, and the same rules apply as described above for meter names.
Each column must specify a metric. Optional parameters can also be set.
As with meters, the metric value must be either a PCP metric name as listed by pminfo(1) or a derived metric. The metric must have an instance domain (set of values) and that instance domain must map to the set of processes with the instance identifier being PIDs (process identifiers). Typically this will be metrics from the proc or hotproc namespace (pmdaproc(1)), but metrics from other domains (pmdabcc(1), pmdabpf(1), etc) that have per-process values are equally applicable.
Column width to use when displaying values for the metric. A negative value can be used to specify left alignment. An upper column limit of 28 characters is enforced. The default column width is 5 characters.
The short title that will be displayed at the head of the column - usually a short, cryptic, all uppercase string.
A short identifying word presented to users on the Setup screen under both the Available and Active Columns lists.
Text that assists users to understand the meaning of this column when it is being presented via the Setup screen in the Available Columns list.
pcp-htop(1), pminfo(1), pmcd(1), pmdaproc(1), pmdabcc(1), pmdabpf(1) and pmRegisterDerived(3).
htop was originally developed by Hisham Muhammad. Nowadays it is maintained by the community at <firstname.lastname@example.org>.
pcp-htop is maintained as a collaboration between the <email@example.com> and <firstname.lastname@example.org> communities, and forms part of the Performance Co-Pilot suite of tools.