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
