PW-TOP(1) General Commands Manual PW-TOP(1)
NAME
pw-top - The PipeWire process viewer
SYNOPSIS
pw-top [options]
DESCRIPTION
The pw-top program provides a dynamic real-time view of the pipewire
node and device statistics.
A hierarchical view is shown of Driver nodes and follower nodes. The
Driver nodes are actively using a timer to schedule dataflow in the
followers. The followers of a driver node as shown below their driver
with a + sign in a tree-like representation.
The columns presented are as follows:
S
Node status.
E = ERROR C = CREATING S = SUSPENDED I = IDLE R = RUNNING
ID The ID of the pipewire node/device, as found in pw-dump and
pw-cli
QUANT The current quantum (for drivers) and the suggested quantum for
follower nodes.
The quantum by itself needs to be divided by the RATE column to
calculate the duration of a scheduling period in fractions of a
second.
For a QUANT of 1024 and a RATE of 48000, the duration of one pe-
riod in the graph is 1024/48000 or 21.3 milliseconds.
Follower nodes can have a 0 QUANT field, which means that the
node does not have a suggestion for the quantum and thus uses
what the driver selected.
The driver will use the lowest quantum of any of the followers.
If none of the followers select a quantum, the default quantum
in the pipewire configuration file will be used.
The QUANT on the drivers usually translates directly into the
number of audio samples processed per processing cycle of the
graph.
See also
https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/FAQ#pipewire-buffering-explained
RATE The current rate (for drivers) and the suggested rate for fol-
lower nodes.
This is the rate at which the graph processes data and needs to
be combined with the QUANT value to derive the duration of a
processing cycle in the graph.
Some nodes can have a 0 RATE, which means that they don't have
any rate suggestion for the graph. Nodes that suggest a rate can
make the graph switch rates if the graph is otherwise idle and
the new rate is allowed as a possible graph rate (see the
pipewire configuration file).
The RATE on (audio) driver nodes usually also translates di-
rectly to the samplerate used by the device. Although some de-
vices might not be able to operate at the given samplerate, in
which case resampling will need to be done. The negotiated sam-
plerate with the device and stream can be found in the FORMAT
column.
WAIT The waiting time of a node is the elapsed time between when the
node is ready to start processing and when it actually started
processing.
For Driver nodes, this is the time between when the node wakes
up to start processing the graph and when the driver (and thus
also the graph) completes a cycle. The WAIT time for driver is
thus the elapsed time processing the graph.
For follower nodes, it is the time spent between being woken up
(when all dependencies of the node are satisfied) and when pro-
cessing starts. The WAIT time for follower nodes is thus mostly
caused by context switching.
A value of --- means that the node was not signaled. A value of
+++ means that the node was signaled but not awake.
BUSY The processing time is started when the node starts processing
until it completes and wakes up the next nodes in the graph.
A value of --- means that the node was not started. A value of
+++ means that the node was started but did not complete.
W/Q Ratio of WAIT / QUANT.
The W/Q time of the driver node is a good measure of the graph
load. The running averages of the driver W/Q ratios are used as
the DSP load in other (JACK) tools.
Values of --- and +++ are copied from the WAIT column.
B/Q Ratio of BUSY / QUANT
This is a good measure of the load of a particular driver or
follower node.
Values of --- and +++ are copied from the BUSY column.
ERR Total of Xruns and Errors
Xruns for drivers are when the graph did not complete a cycle.
This can be because a node in the graph also has an Xrun. It can
also be caused when scheduling delays cause a deadline to be
missed, causing a hardware Xrun.
Xruns for followers are incremented when the node started pro-
cessing but did not complete before the end of the graph cycle
deadline.
FORMAT The format used by the driver node or the stream. This is the
hardware format negotiated with the device or stream.
If the stream of driver has a different rate than the graph, re-
sampling will be done.
For raw audio formats, the layout is <sampleformat> <channels>
<samplerate>.
For IEC958 passthrough audio formats, the layout is IEC958
<codec> <samplerate>.
For DSD formats, the layout is <dsd-rate> <channels>.
For Video formats, the layout is <pixelformat> <width>x<height>.
NAME Name assigned to the device/node, as found in pw-dump node.name
Names are prefixed by + when they are linked to a driver (entry
above with no +)
OPTIONS
-h | --help
Show help.
-r | --remote=NAME
The name the remote instance to monitor. If left unspecified, a
connection is made to the default PipeWire instance.
--version
Show version information.
AUTHORS
The PipeWire Developers <-
https://gitlab.freedesktop.org/pipewire/pipewire/issues>; PipeWire is
available from https://pipewire.org
SEE ALSO
pipewire(1), pw-dump(1), pw-cli(1), pw-profiler(1),
PW-TOP(1)
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