uclamp: Add support for sched utilization clamping

Signed-off-by: Hector Martin <marcan@marcan.st>

conf/apple/j180.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 4
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j274.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 2
 period = 4096
 link_gains = False
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j293.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 8
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j313.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 4
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j314.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 12
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j316.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 12
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j413.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 8
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j415.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 12
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 vsense = VSENSE Switch

conf/apple/j456.conf

@@ -6,6 +6,7 @@ t_window = 20.0
 channels = 8
 period = 4096
 link_gains = True
+uclamp_max = 64
 
 [Controls]
 # vsense = 

src/helpers.rs

@@ -58,6 +58,16 @@ where
         .expect("{}/{}: Out of bounds")
 }
 
+pub fn parse_opt_int<T: TryFrom<i64>>(config: &Ini, section: &str, key: &str) -> Option<T>
+where
+    <T as TryFrom<i64>>::Error: std::fmt::Debug,
+{
+    config
+        .getint(section, key)
+        .expect(&format!("{}/{}: Invalid value", section, key))
+        .map(|a| a.try_into().expect("{}/{}: Out of bounds"))
+}
+
 /**
     Wrapper around configparser::ini::Ini.getfloat()
     to safely unwrap the Result<Option<f64>, E> returned by

src/main.rs

@@ -26,6 +26,7 @@ use simple_logger::SimpleLogger;
 mod blackbox;
 mod helpers;
 mod types;
+mod uclamp;
 
 const DEFAULT_CONFIG_PATH: &str = "share/speakersafetyd";
 
@@ -143,6 +144,13 @@ fn main() {
 
     let globals = types::Globals::parse(&cfg);
 
+    if globals.uclamp_min.is_some() || globals.uclamp_max.is_some() {
+        uclamp::set_uclamp(
+            globals.uclamp_min.unwrap_or(0).try_into().unwrap(),
+            globals.uclamp_max.unwrap_or(1024).try_into().unwrap(),
+        );
+    }
+
     let mut blackbox = args.blackbox_path.map(|p| {
         info!("Enabling blackbox, path: {:?}", p);
         blackbox::Blackbox::new(&machine, &p, &globals)

src/types.rs

@@ -192,6 +192,8 @@ pub struct Globals {
     pub ctl_isense: String,
     pub ctl_amp_gain: String,
     pub ctl_volume: String,
+    pub uclamp_min: Option<usize>,
+    pub uclamp_max: Option<usize>,
 }
 
 impl Globals {
@@ -207,6 +209,8 @@ impl Globals {
             ctl_isense: helpers::parse_string(config, "Controls", "isense"),
             ctl_amp_gain: helpers::parse_string(config, "Controls", "amp_gain"),
             ctl_volume: helpers::parse_string(config, "Controls", "volume"),
+            uclamp_min: helpers::parse_opt_int(config, "Globals", "uclamp_min"),
+            uclamp_max: helpers::parse_opt_int(config, "Globals", "uclamp_max"),
         }
     }
 }

src/uclamp.rs

@@ -0,0 +1,50 @@
+use log::{info, warn};
+
+#[derive(Default)]
+#[repr(C)]
+struct SchedAttr {
+    size: u32,
+    sched_policy: u32,
+    sched_flags: u64,
+    sched_nice: i32,
+    sched_priority: u32,
+    sched_runtime: u64,
+    sched_deadline: u64,
+    sched_period: u64,
+    sched_util_min: u32,
+    sched_util_max: u32,
+}
+
+pub fn set_uclamp(uclamp_min: u32, uclamp_max: u32) {
+    let mut attr: SchedAttr = Default::default();
+    let pid = unsafe { libc::getpid() };
+
+    if unsafe {
+        libc::syscall(
+            libc::SYS_sched_getattr,
+            pid,
+            &mut attr,
+            core::mem::size_of::<SchedAttr>(),
+            0,
+        )
+    } != 0
+    {
+        warn!("Failed to set uclamp");
+        return;
+    }
+
+    /* SCHED_FLAG_KEEP_POLICY |
+     * SCHED_FLAG_KEEP_PARAMS |
+     * SCHED_FLAG_UTIL_CLAMP_MIN |
+     * SCHED_FLAG_UTIL_CLAMP_MAX */
+    attr.sched_flags = 0x8 | 0x10 | 0x20 | 0x40;
+    attr.sched_util_min = uclamp_min;
+    attr.sched_util_max = uclamp_max;
+
+    if unsafe { libc::syscall(libc::SYS_sched_setattr, pid, &mut attr, 0) } != 0 {
+        warn!("Failed to set uclamp");
+        return;
+    }
+
+    info!("Set task uclamp to {}:{}", uclamp_min, uclamp_max);
+}