Unverified Commit 7978d240 authored by Franz Pletz's avatar Franz Pletz Committed by GitHub
Browse files

nixos/iosched: exclude loop devices by default; mention in release notes (#385106)

parents 23d4e8f2 901b87f8

nixos/doc/manual/release-notes/rl-2411.section.md

+2 −0
Original line number Diff line number Diff line
@@ -87,6 +87,8 @@ 


## New Modules {#sec-release-24.11-new-modules}



- [hardware.block](options.html#hardware-block.defaultScheduler) allows configuration of I/O schedulers for block devices.



- [KMonad](https://github.com/kmonad/kmonad), an advanced keyboard remapping utility. Available as [services.kmonad](#opt-services.kmonad.enable).



- [Coral](https://coral.ai/), hardware support for Coral.ai Edge TPU devices. Available as [hardware.coral.usb.enable](#opt-hardware.coral.usb.enable) and [hardware.coral.pcie.enable](#opt-hardware.coral.pcie.enable).

nixos/modules/hardware/iosched.nix

+70 −31
Original line number Diff line number Diff line
@@ -6,24 +6,53 @@ 
}:



let

  inherit (lib)

    concatLines

    concatStringsSep

    mapAttrsToList

    optional

    optionals



    mkIf

    mkOption

    types

    ;



  cfg = config.hardware.block;

  escape = lib.strings.escape [ ''"'' ];



  udevValue = types.addCheck types.nonEmptyStr (x: builtins.match "[^\n\r]*" x != null) // {

    name = "udevValue";

    description = "udev rule value";

    descriptionClass = "noun";

  };



  inherit (lib)

    mkIf

    mkOption

    types



    concatLines

    concatStringsSep

    mapAttrsToList

    optional

    ;

  udevRule =

    {

      rotational ? null,

      include ? null,

      exclude ? null,

      scheduler,

    }:

    concatStringsSep ", " (

      [

        ''SUBSYSTEM=="block"''

        ''ACTION=="add|change"''

        ''TEST=="queue/scheduler"''

      ]

      ++ optionals (rotational != null) [

        ''ATTR{queue/rotational}=="${if rotational then "1" else "0"}"''

      ]

      ++ optionals (include != null) [

        ''KERNEL=="${escape include}"''

      ]

      ++ optionals (exclude != null) [

        ''KERNEL!="${escape exclude}"''

      ]

      ++ [

        ''ATTR{queue/scheduler}="${escape scheduler}"''

      ]

    );

in

{

  options.hardware.block = {
@@ -54,6 +83,22 @@ in 
      example = "bfq";

    };



    defaultSchedulerExclude = mkOption {

      type = types.nullOr udevValue;

      default = "loop[0-9]*";

      description = ''

        Device name pattern to exclude from default scheduler assignment

        through {option}`config.hardware.block.defaultScheduler` and

        {option}`config.hardware.block.defaultSchedulerRotational`.



        By default this excludes loop devices which generally do not benefit

        from extra I/O scheduling in addition to the scheduling already

        performed for their backing devices.



        This setting does not affect {option}`config.hardware.block.scheduler`.

      '';

    };



    scheduler = mkOption {

      type = types.attrsOf udevValue;

      default = { };
@@ -120,27 +165,21 @@ in 
        services.udev.packages = [

          (pkgs.writeTextDir "etc/udev/rules.d/98-block-io-scheduler.rules" (

            concatLines (

              map (concatStringsSep ", ") (

                optional (cfg.defaultScheduler != null) [

                  ''SUBSYSTEM=="block"''

                  ''ACTION=="add|change"''

                  ''TEST=="queue/scheduler"''

                  ''ATTR{queue/scheduler}="${escape cfg.defaultScheduler}"''

                ]

                ++ optional (cfg.defaultSchedulerRotational != null) [

                  ''SUBSYSTEM=="block"''

                  ''ACTION=="add|change"''

                  ''ATTR{queue/rotational}=="1"''

                  ''TEST=="queue/scheduler"''

                  ''ATTR{queue/scheduler}="${escape cfg.defaultSchedulerRotational}"''

                ]

                ++ mapAttrsToList (name: sched: [

                  ''SUBSYSTEM=="block"''

                  ''ACTION=="add|change"''

                  ''KERNEL=="${escape name}"''

                  ''ATTR{queue/scheduler}="${escape sched}"''

                ]) cfg.scheduler

              )

              optional (cfg.defaultScheduler != null) (udevRule {

                exclude = cfg.defaultSchedulerExclude;

                scheduler = cfg.defaultScheduler;

              })

              ++ optional (cfg.defaultSchedulerRotational != null) (udevRule {

                rotational = true;

                exclude = cfg.defaultSchedulerExclude;

                scheduler = cfg.defaultSchedulerRotational;

              })

              ++ mapAttrsToList (

                include: scheduler:

                udevRule {

                  inherit include scheduler;

                }

              ) cfg.scheduler

            )

          ))

        ];

nixos/tests/iosched.nix

+3 −0
Original line number Diff line number Diff line
@@ -63,6 +63,9 @@ import ./make-test-python.nix ( 
      check_scheduler("sdb", "mq-deadline")

      check_scheduler("nvme0n1", "kyber")

      check_scheduler("mmcblk0", "bfq")



      machine.succeed("tmp=\"$(mktemp)\"; losetup /dev/loop0 \"$tmp\"")

      check_scheduler("loop0", "none")

    '';

  }

)