scx_loader: introduce configuration

Cargo.lock

@@ -1763,6 +1763,7 @@ dependencies = [
  "serde",
  "sysinfo",
  "tokio",
+ "toml",
  "zbus",
  "zvariant",
 ]
@@ -1967,6 +1968,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "serde_spanned"
+version = "0.6.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87607cb1398ed59d48732e575a4c28a7a8ebf2454b964fe3f224f2afc07909e1"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "sha1"
 version = "0.10.6"
@@ -2263,11 +2273,26 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "toml"
+version = "0.8.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1ed1f98e3fdc28d6d910e6737ae6ab1a93bf1985935a1193e68f93eeb68d24e"
+dependencies = [
+ "serde",
+ "serde_spanned",
+ "toml_datetime",
+ "toml_edit",
+]
+
 [[package]]
 name = "toml_datetime"
 version = "0.6.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0dd7358ecb8fc2f8d014bf86f6f638ce72ba252a2c3a2572f2a795f1d23efb41"
+dependencies = [
+ "serde",
+]
 
 [[package]]
 name = "toml_edit"
@@ -2276,6 +2301,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "583c44c02ad26b0c3f3066fe629275e50627026c51ac2e595cca4c230ce1ce1d"
 dependencies = [
  "indexmap",
+ "serde",
+ "serde_spanned",
  "toml_datetime",
  "winnow",
 ]

rust/scx_loader/Cargo.toml

@@ -16,5 +16,6 @@ nix = { features = ["process", "signal"], default-features = false, version = "0
 serde = { version = "1.0", features = ["derive"] }
 sysinfo = "0.31.4"
 tokio = { version = "1.39", features = ["macros", "sync", "rt-multi-thread", "process"] }
+toml = "0.8.19"
 zbus = { version = "4", features = ["tokio"], default-features = false }
 zvariant = "4.2"

rust/scx_loader/configuration.md

@@ -0,0 +1,84 @@
+# scx_loader Configuration File
+
+The `scx_loader` can be configured using a TOML file. This file allows you to customize the default scheduler mode, specify custom flags for each supported scheduler and mode, and set a default scheduler to start on boot.
+
+## Configuration File Location
+
+`scx_loader` looks for the configuration file in the following paths (in order):
+
+1. `/etc/scx_loader/config.toml`
+2. `/etc/scx_loader.toml`
+
+If no configuration file is found at any of these paths, `scx_loader` will use the built-in default configuration.
+
+## Configuration Structure
+
+The configuration file has the following structure:
+
+```toml
+default_sched = "scx_bpfland"
+default_mode = "Auto"
+
+[scheds.scx_bpfland]
+auto_mode = []
+gaming_mode = ["-k", "-m", "performance"]
+lowlatency_mode = ["--lowlatency"]
+powersave_mode = ["-m", "powersave"]
+
+[scheds.scx_rusty]
+auto_mode = []
+gaming_mode = []
+lowlatency_mode = []
+powersave_mode = []
+
+[scheds.scx_lavd]
+auto_mode = []
+gaming_mode = ["--performance"]
+lowlatency_mode = ["--performance"]
+powersave_mode = ["--powersave"]
+```
+
+**`default_sched`:**
+
+* This field specifies the scheduler that will be started automatically when `scx_loader` starts (e.g., on boot).
+* It should be set to the name of a supported scheduler (e.g., `"scx_bpfland"`, `"scx_rusty"`, `"scx_lavd"`).
+* If this field is not present or is set to an empty string, no scheduler will be started automatically.
+
+**`default_mode`:**
+
+* This field specifies the default scheduler mode that will be used when starting a scheduler without explicitly specifying a mode.
+* Possible values are: `"Auto"`, `"Gaming"`, `"LowLatency"`, `"PowerSave"`.
+* If this field is not present, it defaults to `"Auto"`.
+
+**`[scheds.scx_name]`:**
+
+* This section defines the custom flags for a specific scheduler. Replace `scx_name` with the actual name of the scheduler (e.g., `scx_bpfland`, `scx_rusty`, `scx_lavd`).
+
+**`auto_mode`, `gaming_mode`, `lowlatency_mode`, `powersave_mode`:**
+
+* These fields specify the flags to be used for each scheduler mode.
+* Each field is an array of strings, where each string represents a flag.
+* If a field is not present or is an empty array, the default flags for that mode will be used.
+
+## Example Configuration
+
+The example configuration above shows how to set custom flags for different schedulers and modes, and how to configure `scx_bpfland` to start automatically on boot.
+
+* For `scx_bpfland`:
+    * Gaming mode: `-k -m performance`
+    * Low Latency mode: `--lowlatency`
+    * Power Save mode: `-m powersave`
+* For `scx_rusty`:
+    * No custom flags are defined, so the default flags for each mode will be used.
+* For `scx_lavd`:
+    * Gaming mode: `--performance`
+    * Low Latency mode: `--performance`
+    * Power Save mode: `--powersave`
+
+## Fallback Behavior
+
+If a specific flag is not defined in the configuration file, `scx_loader` will fall back to the default flags defined in the code.
+
+## Missing Required Fields
+
+If the `default_mode` field is missing, it will default to `"Auto"`. If a `[scheds.scx_name]` section is missing, or if specific mode flags are missing within that section, the default flags for the corresponding scheduler and mode will be used. If `default_sched` is missing or empty, no scheduler will be started automatically.

rust/scx_loader/src/config.rs

@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2024 Vladislav Nepogodin <vnepogodin@cachyos.org>
+
+// This software may be used and distributed according to the terms of the
+// GNU General Public License version 2.
+
+use std::collections::HashMap;
+use std::fs;
+use std::path::Path;
+
+use anyhow::Result;
+use serde::Deserialize;
+
+use crate::get_name_from_scx;
+use crate::SchedMode;
+use crate::SupportedSched;
+
+#[derive(Debug, PartialEq, Default, Deserialize)]
+#[serde(default)]
+pub struct Config {
+    pub default_sched: Option<SupportedSched>,
+    pub default_mode: Option<SchedMode>,
+    pub scheds: HashMap<String, Sched>,
+}
+
+#[derive(Debug, PartialEq, Default, Deserialize)]
+pub struct Sched {
+    pub auto_mode: Option<Vec<String>>,
+    pub gaming_mode: Option<Vec<String>>,
+    pub lowlatency_mode: Option<Vec<String>>,
+    pub powersave_mode: Option<Vec<String>>,
+}
+
+/// Initialize config from first found config path, overwise fallback to default config
+pub fn init_config() -> Result<Config> {
+    if let Ok(config_path) = get_config_path() {
+        parse_config_file(&config_path)
+    } else {
+        Ok(get_default_config())
+    }
+}
+
+pub fn parse_config_file(filepath: &str) -> Result<Config> {
+    let file_content = fs::read_to_string(filepath)?;
+    parse_config_content(&file_content)
+}
+
+pub fn get_config_path() -> Result<String> {
+    // Search in system directories
+    let check_paths = [
+        "/etc/scx_loader/config.toml".to_owned(),
+        "/etc/scx_loader.toml".to_owned(),
+    ];
+    for check_path in check_paths {
+        if !Path::new(&check_path).exists() {
+            continue;
+        }
+        // we found config path
+        return Ok(check_path);
+    }
+
+    anyhow::bail!("Failed to find config!");
+}
+
+fn parse_config_content(file_content: &str) -> Result<Config> {
+    if file_content.is_empty() {
+        anyhow::bail!("The config file is empty!")
+    }
+    let config: Config = toml::from_str(file_content)?;
+    Ok(config)
+}
+
+pub fn get_default_config() -> Config {
+    Config {
+        default_sched: None,
+        default_mode: Some(SchedMode::Auto),
+        scheds: HashMap::from([
+            (
+                "scx_bpfland".to_string(),
+                get_default_sched_for_config(&SupportedSched::Bpfland),
+            ),
+            (
+                "scx_rusty".to_string(),
+                get_default_sched_for_config(&SupportedSched::Rusty),
+            ),
+            (
+                "scx_lavd".to_string(),
+                get_default_sched_for_config(&SupportedSched::Lavd),
+            ),
+        ]),
+    }
+}
+
+/// Get the scx flags for the given sched mode
+pub fn get_scx_flags_for_mode(
+    config: &Config,
+    scx_sched: &SupportedSched,
+    sched_mode: SchedMode,
+) -> Vec<String> {
+    if let Some(sched_config) = config.scheds.get(get_name_from_scx(scx_sched)) {
+        let scx_flags = extract_scx_flags_from_config(sched_config, &sched_mode);
+
+        // try to exact flags from config, otherwise fallback to hardcoded default
+        scx_flags.unwrap_or({
+            get_default_scx_flags_for_mode(scx_sched, sched_mode)
+                .into_iter()
+                .map(String::from)
+                .collect()
+        })
+    } else {
+        get_default_scx_flags_for_mode(scx_sched, sched_mode)
+            .into_iter()
+            .map(String::from)
+            .collect()
+    }
+}
+
+/// Extract the scx flags from config
+fn extract_scx_flags_from_config(
+    sched_config: &Sched,
+    sched_mode: &SchedMode,
+) -> Option<Vec<String>> {
+    match sched_mode {
+        SchedMode::Gaming => sched_config.gaming_mode.clone(),
+        SchedMode::LowLatency => sched_config.lowlatency_mode.clone(),
+        SchedMode::PowerSave => sched_config.powersave_mode.clone(),
+        SchedMode::Auto => sched_config.auto_mode.clone(),
+    }
+}
+
+/// Get Sched object for configuration object
+fn get_default_sched_for_config(scx_sched: &SupportedSched) -> Sched {
+    Sched {
+        auto_mode: Some(
+            get_default_scx_flags_for_mode(scx_sched, SchedMode::Auto)
+                .into_iter()
+                .map(String::from)
+                .collect(),
+        ),
+        gaming_mode: Some(
+            get_default_scx_flags_for_mode(scx_sched, SchedMode::Gaming)
+                .into_iter()
+                .map(String::from)
+                .collect(),
+        ),
+        lowlatency_mode: Some(
+            get_default_scx_flags_for_mode(scx_sched, SchedMode::LowLatency)
+                .into_iter()
+                .map(String::from)
+                .collect(),
+        ),
+        powersave_mode: Some(
+            get_default_scx_flags_for_mode(scx_sched, SchedMode::PowerSave)
+                .into_iter()
+                .map(String::from)
+                .collect(),
+        ),
+    }
+}
+
+/// Get the default scx flags for the given sched mode
+fn get_default_scx_flags_for_mode(scx_sched: &SupportedSched, sched_mode: SchedMode) -> Vec<&str> {
+    match scx_sched {
+        SupportedSched::Bpfland => match sched_mode {
+            SchedMode::Gaming => vec!["-k", "-m", "performance"],
+            SchedMode::LowLatency => vec!["--lowlatency"],
+            SchedMode::PowerSave => vec!["-m", "powersave"],
+            SchedMode::Auto => vec![],
+        },
+        SupportedSched::Lavd => match sched_mode {
+            SchedMode::Gaming | SchedMode::LowLatency => vec!["--performance"],
+            SchedMode::PowerSave => vec!["--powersave"],
+            // NOTE: potentially adding --auto in future
+            SchedMode::Auto => vec![],
+        },
+        // scx_rusty doesn't support any of these modes
+        SupportedSched::Rusty => vec![],
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::config::*;
+
+    #[test]
+    fn test_default_config() {
+        let config_str = r#"
+default_mode = "Auto"
+
+[scheds.scx_bpfland]
+auto_mode = []
+gaming_mode = ["-k", "-m", "performance"]
+lowlatency_mode = ["--lowlatency"]
+powersave_mode = ["-m", "powersave"]
+
+[scheds.scx_rusty]
+auto_mode = []
+gaming_mode = []
+lowlatency_mode = []
+powersave_mode = []
+
+[scheds.scx_lavd]
+auto_mode = []
+gaming_mode = ["--performance"]
+lowlatency_mode = ["--performance"]
+powersave_mode = ["--powersave"]
+"#;
+
+        let parsed_config = parse_config_content(config_str).expect("Failed to parse config");
+        let expected_config = get_default_config();
+
+        assert_eq!(parsed_config, expected_config);
+    }
+
+    #[test]
+    fn test_simple_fallback_config_flags() {
+        let config_str = r#"
+default_mode = "Auto"
+"#;
+
+        let parsed_config = parse_config_content(config_str).expect("Failed to parse config");
+
+        let bpfland_flags =
+            get_scx_flags_for_mode(&parsed_config, &SupportedSched::Bpfland, SchedMode::Gaming);
+        let expected_flags =
+            get_default_scx_flags_for_mode(&SupportedSched::Bpfland, SchedMode::Gaming);
+        assert_eq!(
+            bpfland_flags
+                .iter()
+                .map(|x| x.as_str())
+                .collect::<Vec<&str>>(),
+            expected_flags
+        );
+    }
+
+    #[test]
+    fn test_sched_fallback_config_flags() {
+        let config_str = r#"
+default_mode = "Auto"
+
+[scheds.scx_lavd]
+auto_mode = ["--help"]
+"#;
+
+        let parsed_config = parse_config_content(config_str).expect("Failed to parse config");
+
+        let lavd_flags =
+            get_scx_flags_for_mode(&parsed_config, &SupportedSched::Lavd, SchedMode::Gaming);
+        let expected_flags =
+            get_default_scx_flags_for_mode(&SupportedSched::Lavd, SchedMode::Gaming);
+        assert_eq!(
+            lavd_flags.iter().map(|x| x.as_str()).collect::<Vec<&str>>(),
+            expected_flags
+        );
+
+        let lavd_flags =
+            get_scx_flags_for_mode(&parsed_config, &SupportedSched::Lavd, SchedMode::Auto);
+        assert_eq!(
+            lavd_flags.iter().map(|x| x.as_str()).collect::<Vec<&str>>(),
+            vec!["--help"]
+        );
+    }
+
+    #[test]
+    fn test_empty_config() {
+        let config_str = "";
+        let result = parse_config_content(config_str);
+        assert!(result.is_err());
+    }
+}

rust/scx_loader/src/main.rs

@@ -5,6 +5,7 @@
 // This software may be used and distributed according to the terms of the
 // GNU General Public License version 2.
 
+mod config;
 mod logger;
 
 use std::process::Stdio;
@@ -29,27 +30,40 @@ use zbus::Connection;
 use zvariant::Type;
 use zvariant::Value;
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Deserialize)]
+#[serde(field_identifier, rename_all = "lowercase")]
 enum SupportedSched {
+    #[serde(rename = "scx_bpfland")]
     Bpfland,
+    #[serde(rename = "scx_rusty")]
     Rusty,
+    #[serde(rename = "scx_lavd")]
     Lavd,
 }
 
 #[derive(Debug, PartialEq)]
 enum ScxMessage {
+    /// Quit the scx_loader
     Quit,
+    /// Stop the scheduler, if any
     StopSched,
+    /// Start the scheduler with the given mode
     StartSched((SupportedSched, SchedMode)),
+    /// Start the scheduler with the given scx arguments
     StartSchedArgs((SupportedSched, Vec<String>)),
+    /// Switch to another scheduler with the given mode
     SwitchSched((SupportedSched, SchedMode)),
+    /// Switch to another scheduler with the given scx arguments
     SwitchSchedArgs((SupportedSched, Vec<String>)),
 }
 
 #[derive(Debug, PartialEq)]
 enum RunnerMessage {
+    /// Switch to another scheduler with the given scx arguments
     Switch((SupportedSched, Vec<String>)),
+    /// Start the scheduler with the given scx arguments
     Start((SupportedSched, Vec<String>)),
+    /// Stop the scheduler, if any
     Stop,
 }
 
@@ -84,7 +98,7 @@ impl ScxLoader {
     #[zbus(property)]
     async fn current_scheduler(&self) -> String {
         if let Some(current_scx) = &self.current_scx {
-            let current_scx = get_name_from_scx(&current_scx).into();
+            let current_scx = get_name_from_scx(current_scx).into();
             log::info!("called {current_scx:?}");
             return current_scx;
         }
@@ -181,7 +195,7 @@ impl ScxLoader {
 
     async fn stop_scheduler(&mut self) -> zbus::fdo::Result<()> {
         if let Some(current_scx) = &self.current_scx {
-            let scx_name = get_name_from_scx(&current_scx);
+            let scx_name = get_name_from_scx(current_scx);
 
             log::info!("stopping {scx_name:?}..");
             let _ = self.channel.send(ScxMessage::StopSched);
@@ -192,6 +206,18 @@ impl ScxLoader {
     }
 }
 
+#[zbus::proxy(
+    interface = "org.scx.Loader",
+    default_service = "org.scx.Loader",
+    default_path = "/org/scx/Loader"
+)]
+pub trait LoaderClient {
+    /// Method for switching to the specified scheduler with the given mode.
+    /// This method will stop the currently running scheduler (if any) and
+    /// then start the new scheduler.
+    fn switch_scheduler(&self, scx_name: &str, sched_mode: SchedMode) -> zbus::Result<()>;
+}
+
 // Monitors CPU utilization and enables scx_lavd when utilization of any CPUs is > 90%
 async fn monitor_cpu_util() -> Result<()> {
     let mut system = System::new_all();
@@ -264,6 +290,9 @@ async fn main() -> Result<()> {
 
     let args = Args::parse();
 
+    // initialize the config
+    let config = config::init_config().context("Failed to initialize config")?;
+
     // If --auto is passed, start scx_loader as a standard background process
     // that swaps schedulers out automatically
     // based on CPU utilization without registering a dbus interface.
@@ -300,13 +329,28 @@ async fn main() -> Result<()> {
 
     connection.request_name("org.scx.Loader").await?;
 
+    // if user set default scheduler, then start it
+    if let Some(default_sched) = &config.default_sched {
+        log::info!("Starting default scheduler: {default_sched:?}");
+
+        let default_mode = config.default_mode.clone().unwrap_or(SchedMode::Auto);
+
+        let loader_client = LoaderClientProxy::new(&connection).await?;
+        loader_client
+            .switch_scheduler(get_name_from_scx(default_sched), default_mode)
+            .await?;
+    }
+
     // run worker/receiver loop
-    worker_loop(rx).await?;
+    worker_loop(config, rx).await?;
 
     Ok(())
 }
 
-async fn worker_loop(mut receiver: UnboundedReceiver<ScxMessage>) -> Result<()> {
+async fn worker_loop(
+    config: config::Config,
+    mut receiver: UnboundedReceiver<ScxMessage>,
+) -> Result<()> {
     // setup channel for scheduler runner
     let (runner_tx, runner_rx) = tokio::sync::mpsc::channel::<RunnerMessage>(1);
 
@@ -344,10 +388,7 @@ async fn worker_loop(mut receiver: UnboundedReceiver<ScxMessage>) -> Result<()>
                 log::info!("Got event to start scheduler!");
 
                 // get scheduler args for the mode
-                let args: Vec<_> = get_scx_flags_for_mode(&scx_sched, sched_mode)
-                    .into_iter()
-                    .map(String::from)
-                    .collect();
+                let args = config::get_scx_flags_for_mode(&config, &scx_sched, sched_mode);
 
                 // send message with scheduler and asociated args to the runner
                 runner_tx
@@ -366,10 +407,7 @@ async fn worker_loop(mut receiver: UnboundedReceiver<ScxMessage>) -> Result<()>
                 log::info!("Got event to switch scheduler!");
 
                 // get scheduler args for the mode
-                let args: Vec<_> = get_scx_flags_for_mode(&scx_sched, sched_mode)
-                    .into_iter()
-                    .map(String::from)
-                    .collect();
+                let args = config::get_scx_flags_for_mode(&config, &scx_sched, sched_mode);
 
                 // send message with scheduler and asociated args to the runner
                 runner_tx
@@ -522,25 +560,3 @@ fn get_name_from_scx(supported_sched: &SupportedSched) -> &'static str {
         SupportedSched::Lavd => "scx_lavd",
     }
 }
-
-/// Get the scx flags for the given sched mode
-fn get_scx_flags_for_mode(scx_sched: &SupportedSched, sched_mode: SchedMode) -> Vec<&str> {
-    match scx_sched {
-        SupportedSched::Bpfland => match sched_mode {
-            SchedMode::Gaming => vec!["-c", "0", "-k", "-m", "performance"],
-            SchedMode::LowLatency => vec!["--lowlatency"],
-            SchedMode::PowerSave => vec!["-m", "powersave"],
-            SchedMode::Auto => vec![],
-        },
-        SupportedSched::Lavd => match sched_mode {
-            SchedMode::Gaming | SchedMode::LowLatency => vec!["--performance"],
-            SchedMode::PowerSave => vec!["--powersave"],
-            // NOTE: potentially adding --auto in future
-            SchedMode::Auto => vec![],
-        },
-        // scx_rusty doesn't support any of these modes
-        SupportedSched::Rusty => match sched_mode {
-            _ => vec![],
-        },
-    }
-}