Hi Tudor,
yes, there is one sink input still active (qemu?) which is also the one
that requests the
low latency (requested latency: 0.50 ms). As long as there is an active
stream, the
sink will not be suspended.
I do not see module-loopback in the list of loaded modules. For
module-loopback, the
default latency is 200 ms, so reducing it to 5 ms will surely increase
CPU load. The
default latency is a bit on the large side, I would go for something
between 20ms and
50 ms.
Regards
Georg
On 31.10.22 22:54, Tudor Zaharia wrote:
Hi Georg,
Thank you so much for the quick response!
That sounds like what I need, but unfortunately I have problems with both proposed mitigation measures:
1. Configuring the latency of the null-sink
I couldn't find a setting for it in the documentation (https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/Modules/#module-null-sink) so I tried adding a module-loopback with a latency_msec=5. Unfortunately this increased CPU load even further and even without any clients connected.
Sorry if I sound stupid, but I'm quite new to pulseaudio: I'm guessing that the client itself is requesting this latency when connecting to it? I looked a bit through the client's code but nowhere this value of 500us is set:
pa_buffer_attr ba;
ba.tlength = pa_usec_to_bytes (10 * 1000, &ss);
ba.minreq = pa_usec_to_bytes (5 * 1000, &ss);
ba.maxlength = -1;
ba.prebuf = -1;
int r = pa_stream_connect_playback (stream, dev, ba,
PA_STREAM_INTERPOLATE_TIMING
|PA_STREAM_ADJUST_LATENCY
|PA_STREAM_AUTO_TIMING_UPDATE, NULL, NULL);
From this I'm guessing a latency of 5000us = 5ms, so exactly what you were suggesting. But still pacmd list shows a 500us requested latency value (see below). I don't understand why!
2. Using module-suspend-on-idle
This sounds like a great idea, but the output sink (emulator_out) is always running, so it doesn't get suspended, although there is no sound coming from the client. Same, I don't understand why it is still in running state!
$ pacmd list
Memory blocks currently allocated: 1, size: 63.9 KiB.
Memory blocks allocated during the whole lifetime: 7789, size: 794.0 KiB.
Memory blocks imported from other processes: 0, size: 0 B.
Memory blocks exported to other processes: 0, size: 0 B.
Total sample cache size: 0 B.
Default sample spec: s16le 2ch 48000Hz
Default channel map: front-left,front-right
Default sink name: emulator_out
Default source name: emulator_out.monitor
Memory blocks of type POOL: 1 allocated/7789 accumulated.
Memory blocks of type POOL_EXTERNAL: 0 allocated/0 accumulated.
Memory blocks of type APPENDED: 0 allocated/0 accumulated.
Memory blocks of type USER: 0 allocated/0 accumulated.
Memory blocks of type FIXED: 0 allocated/0 accumulated.
Memory blocks of type IMPORTED: 0 allocated/0 accumulated.
5 module(s) loaded.
index: 0
name: <module-null-sink>
argument: <sink_name=emulator_out sink_properties=device.description=emulator_out format=s16le rate=48000 channels=2 channel_map=front-left,front-right>
used: 1
load once: no
properties:
module.author = "Lennart Poettering"
module.description = "Clocked NULL sink"
module.version = "10.0"
index: 1
name: <module-null-sink>
argument: <sink_name=emulator_in sink_properties=device.description=emulator_in format=s16le rate=48000 channels=2 channel_map=front-left,front-right>
used: 1
load once: no
properties:
module.author = "Lennart Poettering"
module.description = "Clocked NULL sink"
module.version = "10.0"
index: 2
name: <module-suspend-on-idle>
argument: <timeout=2>
used: -1
load once: yes
properties:
module.author = "Lennart Poettering"
module.description = "When a sink/source is idle for too long, suspend it"
module.version = "10.0"
index: 3
name: <module-native-protocol-unix>
argument: <auth-anonymous=1 socket=/pa/pulse-socket>
used: -1
load once: no
properties:
module.author = "Lennart Poettering"
module.description = "Native protocol (UNIX sockets)"
module.version = "10.0"
index: 4
name: <module-cli-protocol-unix>
argument: <>
used: -1
load once: no
properties:
module.author = "Lennart Poettering"
module.description = "Command line interface protocol (UNIX sockets)"
module.version = "10.0"
2 sink(s) available.
* index: 0
name: <emulator_out>
driver: <module-null-sink.c>
flags: DECIBEL_VOLUME LATENCY FLAT_VOLUME DYNAMIC_LATENCY
state: RUNNING
suspend cause:
priority: 1000
volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
base volume: 65536 / 100% / 0.00 dB
volume steps: 65537
muted: no
current latency: 0.38 ms
max request: 0 KiB
max rewind: 0 KiB
monitor source: 0
sample spec: s16le 2ch 48000Hz
channel map: front-left,front-right
Stereo
used by: 1
linked by: 1
configured latency: 0.50 ms; range is 0.50 .. 2000.00 ms
module: 0
properties:
device.description = "emulator_out"
device.class = "abstract"
device.icon_name = "audio-card"
index: 1
name: <emulator_in>
driver: <module-null-sink.c>
flags: DECIBEL_VOLUME LATENCY FLAT_VOLUME DYNAMIC_LATENCY
state: SUSPENDED
suspend cause: IDLE
priority: 1000
volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
base volume: 65536 / 100% / 0.00 dB
volume steps: 65537
muted: no
current latency: 0.00 ms
max request: 1 KiB
max rewind: 1 KiB
monitor source: 1
sample spec: s16le 2ch 48000Hz
channel map: front-left,front-right
Stereo
used by: 0
linked by: 1
configured latency: 0.00 ms; range is 0.50 .. 2000.00 ms
module: 1
properties:
device.description = "emulator_in"
device.class = "abstract"
device.icon_name = "audio-card"
2 source(s) available.
* index: 0
name: <emulator_out.monitor>
driver: <module-null-sink.c>
flags: DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
state: IDLE
suspend cause:
priority: 1000
volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
base volume: 65536 / 100% / 0.00 dB
volume steps: 65537
muted: no
current latency: 0.00 ms
max rewind: 0 KiB
sample spec: s16le 2ch 48000Hz
channel map: front-left,front-right
Stereo
used by: 0
linked by: 0
configured latency: 2000.00 ms; range is 0.50 .. 2000.00 ms
monitor_of: 0
module: 0
properties:
device.description = "Monitor of emulator_out"
device.class = "monitor"
device.icon_name = "audio-input-microphone"
index: 1
name: <emulator_in.monitor>
driver: <module-null-sink.c>
flags: DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
state: SUSPENDED
suspend cause: IDLE
priority: 1000
volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
base volume: 65536 / 100% / 0.00 dB
volume steps: 65537
muted: no
current latency: 0.00 ms
max rewind: 1 KiB
sample spec: s16le 2ch 48000Hz
channel map: front-left,front-right
Stereo
used by: 0
linked by: 1
configured latency: 0.00 ms; range is 0.50 .. 2000.00 ms
monitor_of: 1
module: 1
properties:
device.description = "Monitor of emulator_in"
device.class = "monitor"
device.icon_name = "audio-input-microphone"
2 client(s) logged in.
index: 2
driver: <protocol-native.c>
owner module: 3
properties:
application.name = "unix:/tmp/pa-docker/pulse-socket"
native-protocol.peer = "UNIX socket client"
native-protocol.version = "33"
application.process.id = "55569"
application.process.user = "tudor"
application.process.host = "machine"
application.process.binary = "qemu-system-x86_64"
application.language = "C"
window.x11.display = ":1"
application.process.machine_id = "c6ba133539f0416791786992742aa11c"
index: 3
driver: <cli.c>
owner module: 4
properties:
application.name = "UNIX socket client"
0 card(s) available.
1 sink input(s) available.
index: 0
driver: <protocol-native.c>
flags:
state: DRAINED
sink: 0 <emulator_out>
volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
muted: no
current latency: 0.00 ms
requested latency: 0.50 ms
sample spec: s16le 2ch 48000Hz
channel map: front-left,front-right
Stereo
resample method: (null)
module: 3
client: 2 <unix:/tmp/pa-docker/pulse-socket>
properties:
media.name = "qemu"
application.name = "unix:/tmp/pa-docker/pulse-socket"
native-protocol.peer = "UNIX socket client"
native-protocol.version = "33"
application.process.id = "55569"
application.process.user = "tudor"
application.process.host = "machine"
application.process.binary = "qemu-system-x86_64"
application.language = "C"
window.x11.display = ":1"
application.process.machine_id = "c6ba133539f0416791786992742aa11c"
1 source output(s) available.
index: 0
driver: <protocol-native.c>
flags: START_CORKED
state: CORKED
source: 1 <emulator_in.monitor>
volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
muted: no
current latency: 0.00 ms
requested latency: 10.00 ms
sample spec: s16le 2ch 48000Hz
channel map: front-left,front-right
Stereo
resample method: (null)
owner module: 3
client: 2 <unix:/tmp/pa-docker/pulse-socket>
properties:
media.name = "qemu"
application.name = "unix:/tmp/pa-docker/pulse-socket"
native-protocol.peer = "UNIX socket client"
native-protocol.version = "33"
application.process.id = "55569"
application.process.user = "tudor"
application.process.host = "machine"
application.process.binary = "qemu-system-x86_64"
application.language = "C"
window.x11.display = ":1"
application.process.machine_id = "c6ba133539f0416791786992742aa11c"
0 cache entrie(s) available.
Best regards,
Tudor
