refactor(walltime): share Linux profiler sysctl setup

Move the Linux profiling sysctl setup out of the perf profiler and into a shared walltime profiler helper. This lets both perf and samply prepare kernel symbol access and non-root profiling consistently while preserving the existing sudo-based behavior.

Author: not-matthias

src/executor/wall_time/profiler/linux_sysctl.rs

@@ -0,0 +1,68 @@
+use crate::prelude::*;
+
+#[cfg(target_os = "linux")]
+use crate::executor::helpers::run_with_sudo::run_with_sudo;
+#[cfg(any(test, target_os = "linux"))]
+use anyhow::Context;
+#[cfg(target_os = "linux")]
+use std::process::Command;
+
+pub fn ensure_linux_profiling_sysctls() -> Result<()> {
+    #[cfg(target_os = "linux")]
+    {
+        ensure_sysctl("kernel.kptr_restrict", 0)?;
+        ensure_sysctl("kernel.perf_event_paranoid", -1)?;
+    }
+
+    Ok(())
+}
+
+#[cfg(target_os = "linux")]
+fn ensure_sysctl(name: &str, target_value: i64) -> Result<()> {
+    if sysctl_read(name)? == target_value {
+        return Ok(());
+    }
+
+    let assignment = format!("{name}={target_value}");
+    run_with_sudo("sysctl", ["-w", assignment.as_str()])
+}
+
+#[cfg(target_os = "linux")]
+fn sysctl_read(name: &str) -> Result<i64> {
+    let output = Command::new("sysctl").arg(name).output()?;
+    let output = String::from_utf8(output.stdout)?;
+
+    parse_sysctl_value(&output)
+}
+
+#[cfg(any(test, target_os = "linux"))]
+fn parse_sysctl_value(output: &str) -> Result<i64> {
+    let (_, value) = output
+        .split_once('=')
+        .context("Couldn't find the value in sysctl output")?;
+
+    Ok(value.trim().parse::<i64>()?)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_sysctl_value() {
+        assert_eq!(parse_sysctl_value("kernel.kptr_restrict = 0\n").unwrap(), 0);
+    }
+
+    #[test]
+    fn parses_negative_sysctl_value() {
+        assert_eq!(
+            parse_sysctl_value("kernel.perf_event_paranoid = -1\n").unwrap(),
+            -1
+        );
+    }
+
+    #[test]
+    fn rejects_sysctl_output_without_value_separator() {
+        assert!(parse_sysctl_value("kernel.kptr_restrict 0\n").is_err());
+    }
+}

src/executor/wall_time/profiler/mod.rs

@@ -4,6 +4,7 @@
 //! (perf, samply, instruments, ...) and produces a unified set of artifacts
 //! in the profile folder.
 
+mod linux_sysctl;
 pub mod perf;
 pub mod samply;
 

src/executor/wall_time/profiler/perf/mod.rs

@@ -8,11 +8,11 @@ use crate::executor::helpers::detect_executable::command_has_executable;
 use crate::executor::helpers::env::is_codspeed_debug_enabled;
 use crate::executor::helpers::env::suppress_go_perf_unwinding_warning;
 use crate::executor::helpers::harvest_perf_maps_for_pids::harvest_perf_maps_for_pids;
-use crate::executor::helpers::run_with_sudo::run_with_sudo;
 use crate::executor::helpers::run_with_sudo::wrap_with_sudo;
 use crate::executor::shared::fifo::FifoBenchmarkData;
 use crate::executor::wall_time::profiler::Profiler;
 use crate::executor::wall_time::profiler::WALLTIME_METADATA_CURRENT_VERSION;
+use crate::executor::wall_time::profiler::linux_sysctl::ensure_linux_profiling_sysctls;
 use crate::executor::wall_time::profiler::perf::perf_executable::get_working_perf_executable;
 use crate::prelude::*;
 use crate::system::SystemInfo;
@@ -75,30 +75,7 @@ impl Profiler for PerfProfiler {
         setup_cache_dir: Option<&Path>,
     ) -> anyhow::Result<()> {
         setup::install_perf(system_info, setup_cache_dir).await?;
-
-        let sysctl_read = |name: &str| -> anyhow::Result<i64> {
-            let output = std::process::Command::new("sysctl").arg(name).output()?;
-            let output = String::from_utf8(output.stdout)?;
-
-            Ok(output
-                .split(" = ")
-                .last()
-                .context("Couldn't find the value in sysctl output")?
-                .trim()
-                .parse::<i64>()?)
-        };
-
-        // Allow access to kernel symbols
-        if sysctl_read("kernel.kptr_restrict")? != 0 {
-            run_with_sudo("sysctl", ["-w", "kernel.kptr_restrict=0"])?;
-        }
-
-        // Allow non-root profiling
-        if sysctl_read("kernel.perf_event_paranoid")? != -1 {
-            run_with_sudo("sysctl", ["-w", "kernel.perf_event_paranoid=-1"])?;
-        }
-
-        Ok(())
+        ensure_linux_profiling_sysctls()
     }
 
     async fn wrap(

src/executor/wall_time/profiler/samply/mod.rs

@@ -4,6 +4,7 @@ use crate::executor::ExecutorConfig;
 use crate::executor::helpers::command::CommandBuilder;
 use crate::executor::shared::fifo::FifoBenchmarkData;
 use crate::executor::wall_time::profiler::Profiler;
+use crate::executor::wall_time::profiler::linux_sysctl::ensure_linux_profiling_sysctls;
 use crate::prelude::*;
 use async_trait::async_trait;
 use runner_shared::artifacts::ArtifactExt;
@@ -32,6 +33,14 @@ impl SamplyProfiler {
 
 #[async_trait(?Send)]
 impl Profiler for SamplyProfiler {
+    async fn setup(
+        &self,
+        _system_info: &SystemInfo,
+        _setup_cache_dir: Option<&Path>,
+    ) -> anyhow::Result<()> {
+        ensure_linux_profiling_sysctls()
+    }
+
     async fn wrap(
         &mut self,
         mut cmd_builder: CommandBuilder,