Lumpiasty
c9e6ec7b23
EasyEffects DSP plugins (rnnoise, deepfilternet, crystalizer) drop audio when the system is under load. Layered workaround with per-optimization toggles for bisecting impact: - cgroup-based CPU partitioning: dedicated audio.slice with AllowedCPUs pinning, restricted app/session/background slices for everything else - rlimits so PipeWire's module-rt sets SCHED_FIFO 88 directly instead of going through RTKit's priority-10 ceiling - persistent watcher that re-applies performance governor on audio cores (gamemoded/PPD keep resetting it) - ananicy rule pinning easyeffects to nice -12 for non-RT DSP threads - znver4-tuned rebuilds of easyeffects and its DSP deps Master switch + per-feature toggles via lumpiasty.audioRt.*; all enabled by default on acer host. None of this fully eliminates dropouts on this thermally constrained laptop but each layer is independently testable.
234 lines
8.3 KiB
Nix
234 lines
8.3 KiB
Nix
{ config, lib, pkgs, ... }:
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# Workarounds for audio xruns under CPU load.
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#
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# Each optimization is independently toggleable so behavior can be bisected.
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# `lumpiasty.audioRt.enable` is the master switch; individual sub-flags default
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# to `true` when the master is on and can be flipped per-host to test impact.
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let
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cfg = config.lumpiasty.audioRt;
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marchFlags = " -march=znver4 -O3";
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# ---------------------------------------------------------------------------
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# Per-build-system helpers (see commit history for rationale on LTO choices).
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# ---------------------------------------------------------------------------
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withMarch = pkg: pkg.overrideAttrs (old: {
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env = (old.env or {}) // {
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NIX_CFLAGS_COMPILE =
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((old.env or {}).NIX_CFLAGS_COMPILE or old.NIX_CFLAGS_COMPILE or "")
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+ marchFlags;
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};
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});
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cmakePkg = pkg: pkg.overrideAttrs (old: {
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env = (old.env or {}) // {
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NIX_CFLAGS_COMPILE =
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((old.env or {}).NIX_CFLAGS_COMPILE or old.NIX_CFLAGS_COMPILE or "")
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+ marchFlags;
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};
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cmakeFlags = (old.cmakeFlags or []) ++ [ "-DCMAKE_INTERPROCEDURAL_OPTIMIZATION=ON" ];
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preConfigure = (old.preConfigure or "") + "\nexport AR=gcc-ar\n";
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});
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rustPkg = pkg: pkg.overrideAttrs (old: {
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RUSTFLAGS = (old.RUSTFLAGS or "") + " -C target-cpu=znver4";
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});
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in
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{
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options.lumpiasty.audioRt = {
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enable = lib.mkEnableOption "Audio RT scheduling and CPU isolation";
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audioCpus = lib.mkOption {
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type = lib.types.str;
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default = "12-15";
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description = "CPU list reserved for audio services (systemd cpuset syntax).";
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};
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nonAudioCpus = lib.mkOption {
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type = lib.types.str;
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default = "0-11";
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description = "CPU list for everything else.";
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};
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# ------ Individual optimization toggles ------
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cpuPartitioning = lib.mkOption {
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type = lib.types.bool;
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default = cfg.enable;
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description = ''
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Cgroup-based CPU partitioning via dedicated audio.slice and
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restricted app/session/background slices.
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'';
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};
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rtLimits = lib.mkOption {
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type = lib.types.bool;
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default = cfg.enable;
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description = ''
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Raise rlimits (RTPRIO=95, MEMLOCK=infinity) for the audio group
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so PipeWire's module-rt can set SCHED_FIFO 88 directly instead
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of going through RTKit's priority-10 ceiling.
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'';
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};
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performanceGovernor = lib.mkOption {
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type = lib.types.bool;
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default = cfg.enable;
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description = ''
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Keep cpufreq governor `performance` on the audio cores so they
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stay boosted regardless of measured utilization.
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'';
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};
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ananicy = lib.mkOption {
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type = lib.types.bool;
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default = cfg.enable;
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description = ''
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Run ananicy-cpp with a rule that pins easyeffects to nice -12 so
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its non-RT DSP threads get scheduler preference under load.
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'';
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};
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optimisedBinaries = lib.mkOption {
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type = lib.types.bool;
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default = cfg.enable;
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description = ''
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Rebuild easyeffects and its DSP dependencies with -march=znver4 -O3
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(and LTO for cmake builds, target-cpu for rust builds).
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'';
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};
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};
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config = lib.mkMerge [
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# --- Optimised binary builds ---------------------------------------------
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(lib.mkIf (cfg.enable && cfg.optimisedBinaries) {
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nixpkgs.overlays = [
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(final: prev: {
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easyeffects = cmakePkg (prev.easyeffects.override {
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fftw = withMarch prev.fftw;
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fftwFloat = withMarch prev.fftwFloat;
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speexdsp = withMarch prev.speexdsp;
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rubberband = withMarch prev.rubberband;
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soundtouch = withMarch prev.soundtouch;
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zita-convolver = withMarch prev.zita-convolver;
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webrtc-audio-processing = withMarch prev.webrtc-audio-processing;
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rnnoise = withMarch prev.rnnoise;
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libebur128 = cmakePkg prev.libebur128;
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libbs2b = withMarch prev.libbs2b;
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lilv = withMarch prev.lilv;
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onetbb = cmakePkg prev.onetbb;
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calf = cmakePkg prev.calf;
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lsp-plugins = withMarch prev.lsp-plugins;
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zam-plugins = withMarch prev.zam-plugins;
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mda_lv2 = withMarch prev.mda_lv2;
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deepfilternet = rustPkg prev.deepfilternet;
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});
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})
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];
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})
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# --- RT scheduling rlimits ----------------------------------------------
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(lib.mkIf (cfg.enable && cfg.rtLimits) {
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security.pam.loginLimits = [
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{ domain = "@audio"; type = "-"; item = "rtprio"; value = "95"; }
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{ domain = "@audio"; type = "-"; item = "memlock"; value = "unlimited"; }
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{ domain = "@audio"; type = "-"; item = "nice"; value = "-20"; }
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];
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systemd.user.extraConfig = ''
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DefaultLimitRTPRIO=95
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DefaultLimitMEMLOCK=infinity
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'';
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})
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# --- CPU partitioning (cgroup-based) ------------------------------------
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#
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# Cgroup hierarchy under user@.service:
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# ├── app.slice AllowedCPUs=<nonAudioCpus> (Steam-launched apps)
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# ├── session.slice AllowedCPUs=<nonAudioCpus> (kwin, plasmashell, kded)
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# ├── background.slice AllowedCPUs=<nonAudioCpus> (akonadi, polkit)
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# └── audio.slice AllowedCPUs=<audioCpus> (pipewire, easyeffects)
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#
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# Reasoning:
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# - No isolcpus= : breaks scheduler load balancing on the rest of the system.
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# - No nohz_full= : amd-pstate can't sample utilization in tickless mode
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# so cores get clamped at minimum frequency.
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# - No rcu_nocbs= : microsecond-scale jitter is irrelevant at 21ms quantum.
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(lib.mkIf (cfg.enable && cfg.cpuPartitioning) {
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systemd.user.extraConfig = ''
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CPUAffinity=${cfg.nonAudioCpus}
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'';
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systemd.settings.Manager.CPUAffinity = cfg.nonAudioCpus;
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# Delegate the cpuset controller to user managers so user-level slices
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# can use AllowedCPUs=.
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systemd.services."user@".serviceConfig.Delegate = "cpu cpuset io memory pids";
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systemd.user.slices = {
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app.sliceConfig.AllowedCPUs = cfg.nonAudioCpus;
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session.sliceConfig.AllowedCPUs = cfg.nonAudioCpus;
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background.sliceConfig.AllowedCPUs = cfg.nonAudioCpus;
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audio = {
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description = "Audio services pinned to reserved CPU cores";
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sliceConfig.AllowedCPUs = cfg.audioCpus;
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};
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};
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# easyeffects.service Slice= is set in home-modules/pc.nix.
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systemd.user.services.pipewire.serviceConfig.Slice = "audio.slice";
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systemd.user.services.pipewire-pulse.serviceConfig.Slice = "audio.slice";
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systemd.user.services.wireplumber.serviceConfig.Slice = "audio.slice";
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})
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# --- Performance governor on audio cores --------------------------------
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(lib.mkIf (cfg.enable && cfg.performanceGovernor) {
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systemd.services.audio-cores-performance = {
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description = "Keep performance governor on audio cores";
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wantedBy = [ "multi-user.target" ];
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after = [ "multi-user.target" ];
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serviceConfig = {
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Type = "simple";
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Restart = "always";
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RestartSec = "5s";
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# Expand systemd CPU list ("12-15" / "12,13,14,15") into a flat list.
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ExecStart = pkgs.writeShellScript "audio-cores-performance" ''
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cpus=$(echo "${cfg.audioCpus}" | ${pkgs.coreutils}/bin/tr ',' ' ' | \
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${pkgs.gawk}/bin/awk '{
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for (i=1; i<=NF; i++) {
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if (match($i, /^([0-9]+)-([0-9]+)$/, m))
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for (j=m[1]; j<=m[2]; j++) print j
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else print $i
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}
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}')
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while true; do
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for cpu in $cpus; do
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cur=$(cat /sys/devices/system/cpu/cpu$cpu/cpufreq/scaling_governor)
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if [ "$cur" != "performance" ]; then
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echo performance > /sys/devices/system/cpu/cpu$cpu/cpufreq/scaling_governor
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fi
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done
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sleep 2
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done
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'';
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};
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};
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})
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# --- Ananicy rule for easyeffects ---------------------------------------
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(lib.mkIf (cfg.enable && cfg.ananicy) {
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services.ananicy = {
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enable = true;
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package = pkgs.ananicy-cpp;
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extraRules = [
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{ name = "easyeffects"; type = "Audio"; nice = -12; }
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];
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};
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})
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];
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}
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