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174 lines
5.3 KiB
ReStructuredText
174 lines
5.3 KiB
ReStructuredText
pw-top
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######
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---------------------------
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The PipeWire process viewer
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---------------------------
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:Manual section: 1
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:Manual group: General Commands Manual
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SYNOPSIS
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========
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| **pw-top** [*options*]
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DESCRIPTION
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===========
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The *pw-top* program provides a dynamic real-time view of the pipewire
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node and device statistics.
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A hierarchical view is shown of Driver nodes and follower nodes. The Driver
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nodes are actively using a timer to schedule dataflow in the followers. The
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followers of a driver node as shown below their driver with a + sign in
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a tree-like representation.
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The columns presented are as follows:
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S
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Measurement status.
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! representing inactive - no connections
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Blank representing active
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ID
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The ID of the pipewire node/device, as found in *pw-dump*
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QUANT
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The current quantum (for drivers) and the suggested quantum for follower
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nodes.
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The quantum by itself needs to be divided by the RATE column to calculate
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the duration of a scheduling period in fractions of a second.
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For a QUANT of 1024 and a RATE of 48000, the duration of one period in the
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graph is 1024/48000 or 21.3 milliseconds.
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Follower nodes can have a 0 QUANT field, which means that the node does not
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have a suggestion for the quantum and thus uses what the driver selected.
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The driver will use the lowest quantum of any of the followers. If none of
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the followers select a quantum, the default quantum in the pipewire configuration
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file will be used.
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The QUANT on the drivers usually translates directly into the number of audio
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samples processed per processing cycle of the graph.
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See also https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/FAQ#pipewire-buffering-explained
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RATE
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The current rate (for drivers) and the suggested rate for follower
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nodes.
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This is the rate at which the *graph* processes data and needs to be combined with
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the QUANT value to derive the duration of a processing cycle in the graph.
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Some nodes can have a 0 RATE, which means that they don't have any rate
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suggestion for the graph. Nodes that suggest a rate can make the graph switch
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rates if the graph is otherwise idle and the new rate is allowed as
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a possible graph rate (see the pipewire configuration file).
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The RATE on (audio) driver nodes usually also translates directly to the
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samplerate used by the device. Although some devices might not be able to
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operate at the given samplerate, in which case resampling will need to be
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done. The negotiated samplerate with the device and stream can be found in
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the FORMAT column.
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WAIT
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The waiting time of a node is the elapsed time between when the node
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is ready to start processing and when it actually started processing.
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For Driver nodes, this is the time between when the node wakes up to
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start processing the graph and when the driver (and thus also the graph)
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completes a cycle. The WAIT time for driver is thus the elapsed time
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processing the graph.
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For follower nodes, it is the time spent between being woken up (when all
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dependencies of the node are satisfied) and when processing starts. The
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WAIT time for follower nodes is thus mostly caused by context switching.
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A value of --- means that the node was not signaled. A value of +++
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means that the node was signaled but not awake.
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BUSY
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The processing time is started when the node starts processing until it
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completes and wakes up the next nodes in the graph.
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A value of --- means that the node was not started. A value of +++
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means that the node was started but did not complete.
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W/Q
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Ratio of WAIT / QUANT.
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The W/Q time of the driver node is a good measure of the graph
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load. The running averages of the driver W/Q ratios are used as the DSP
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load in other (JACK) tools.
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Values of --- and +++ are copied from the WAIT column.
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B/Q
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Ratio of BUSY / QUANT
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This is a good measure of the load of a particular driver or follower
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node.
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Values of --- and +++ are copied from the BUSY column.
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ERR
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Total of Xruns and Errors
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Xruns for drivers are when the graph did not complete a cycle. This can
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be because a node in the graph also has an Xrun. It can also be caused when
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scheduling delays cause a deadline to be missed, causing a hardware
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Xrun.
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Xruns for followers are incremented when the node started processing but
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did not complete before the end of the graph cycle deadline.
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FORMAT
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The format used by the driver node or the stream. This is the hardware format
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negotiated with the device or stream.
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If the stream of driver has a different rate than the graph, resampling will
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be done.
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For raw audio formats, the layout is <sampleformat> <channels> <samplerate>.
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For DSD formats, the layout is <dsd-rate> <channels>.
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For Video formats, the layout is <pixelformat> <width>x<height>.
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NAME
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Name assigned to the device/node, as found in *pw-dump* node.name
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Names are prefixed by *+* when they are linked to a driver (entry above with no +)
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OPTIONS
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=======
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-h | --help
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Show help.
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-r | --remote=NAME
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The name the *remote* instance to monitor. If left unspecified,
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a connection is made to the default PipeWire instance.
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--version
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Show version information.
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AUTHORS
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=======
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The PipeWire Developers <@PACKAGE_BUGREPORT@>; PipeWire is available from @PACKAGE_URL@
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SEE ALSO
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========
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``pipewire(1)``,
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``pw-dump(1)``,
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``pw-cli(1)``,
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``pw-profiler(1)``,
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