WIP: pipewire: trying to tune so lima doesnt crash

hosts/common/programs/pipewire.nix

@@ -82,6 +82,24 @@ in
         default.clock.max-quantum = ${builtins.toString cfg.config.max-quantum}
       }
     '';
+    fs.".config/pipewire/pipewire.conf.d/20-sane-rtkit.conf".symlink.text = ''
+      # documented inside <repo:pipewire/pipewire:/src/modules/module-rt.c>
+      context.modules = [{
+        name = libpipewire-module-rt
+        args = {
+          nice.level   = 0
+          #rt.prio      = 88
+          #rt.time.soft = -1
+          #rt.time.hard = -1
+          #rlimits.enabled = true
+          #rtportal.enabled = true
+          #rtkit.enabled = true
+          #uclamp.min = 0
+          #uclamp.max = 1024
+        }
+        flags = [ ifexists nofail ]
+      }]
+    '';
 
     # see: <https://docs.pipewire.org/page_module_protocol_native.html>
     # defaults to placing the socket in /run/user/$id/{pipewire-0,pipewire-0-manager,...}

hosts/common/programs/rtkit.nix

@@ -25,8 +25,8 @@ in
       ExecStart = lib.escapeShellArgs [
         "${cfg.package}/libexec/rtkit-daemon"
         "--scheduling-policy=FIFO"
-        "--our-realtime-priority=89"
-        "--max-realtime-priority=88"
+        "--our-realtime-priority=79"
+        "--max-realtime-priority=78"  # N.B.: setting this too aggressively can hang weak devices!
         "--min-nice-level=-19"
         "--rttime-usec-max=2000000"
         "--users-max=100"

hosts/common/programs/wireplumber.nix

@@ -2,10 +2,10 @@
 {
   sane.programs.wireplumber = {
     sandbox.method = "bwrap";
-    sandbox.whitelistDbus = [
-      "system"  #< so it can request better scheduling from rtkit
-      "user"  #< TODO: is this needed?
-    ];
+    # sandbox.whitelistDbus = [
+    #   "system"  #< so it can request better scheduling from rtkit
+    #   # "user"  #< TODO: is this needed?
+    # ];
     sandbox.whitelistAudio = true;
     sandbox.extraPaths = [
       # i think these video inputs (for e.g. webcam) are optional.
@@ -20,10 +20,10 @@
       "/sys/class/video4linux"
       "/sys/devices"
     ];
-    sandbox.extraConfig = [
-      # needed if i want rtkit to grant this higher scheduling priority
-      "--sane-sandbox-keep-namespace" "pid"
-    ];
+    # sandbox.extraConfig = [
+    #   # needed if i want rtkit to grant this higher scheduling priority
+    #   "--sane-sandbox-keep-namespace" "pid"
+    # ];
 
     suggestedPrograms = [ "alsa-ucm-conf" ];