feat: script for setting kernel tunables and check when running neard (…

…#12577)

Standalone script for setting the recommended networking settings on
Linux and addition of a check when starting neard. If the settings are
not right, errors will be printed without halting the process.

---------

Co-authored-by: Razvan Barbascu <razvan@nearone.org>
Co-authored-by: Akhilesh Singhania <akhi3030@gmail.com>

neard/src/cli.rs

@@ -459,6 +459,7 @@ impl RunCmd {
             .unwrap_or_else(|e| panic!("Error loading config: {:#}", e));
 
         check_release_build(&near_config.client_config.chain_id);
+        check_kernel_params();
 
         // Set current version in client config.
         near_config.client_config.version = crate::neard_version();
@@ -808,6 +809,62 @@ impl ValidateConfigCommand {
     }
 }
 
+#[cfg(target_os = "linux")]
+fn normalize_whitespace(s: &str) -> String {
+    s.split_whitespace().collect::<Vec<_>>().join(" ")
+}
+
+/// Checks the provided kernel parameter  from /proc/sys
+/// and prints an error if it is not set to the expected value.
+#[cfg(target_os = "linux")]
+fn check_kernel_param(param_name: &str, expected_value: &str) {
+    // Convert the dotted param_name into a path under /proc/sys
+    // For example, "net.core.rmem_max" -> "/proc/sys/net/core/rmem_max"
+    let mut path = PathBuf::from("/proc/sys");
+    for part in param_name.split('.') {
+        path.push(part);
+    }
+
+    match std::fs::read_to_string(&path) {
+        Ok(contents) => {
+            let actual = contents.trim();
+            let actual_normalized = normalize_whitespace(actual);
+            let expected_normalized = normalize_whitespace(expected_value);
+
+            if actual_normalized != expected_normalized {
+                error!(
+                    "ERROR: {} is set to {}, expected {}. Please run `scripts/set_kernel_params.sh`.",
+                    param_name, actual_normalized, expected_normalized
+                );
+            } else {
+                info!("OK: {} is set to expected value {}", param_name, expected_normalized);
+            }
+        }
+        Err(e) => {
+            error!("ERROR: failed to read parameter {} from {}: {}", param_name, path.display(), e);
+        }
+    }
+}
+
+#[cfg(not(target_os = "linux"))]
+fn check_kernel_params() {}
+
+/// Checks if the system has the expected values for the sysctl parameters for optimal networking performance.
+#[cfg(target_os = "linux")]
+fn check_kernel_params() {
+    let expected_rmem_max = "8388608";
+    let expected_wmem_max = "8388608";
+    let expected_tcp_rmem = "4096 87380 8388608";
+    let expected_tcp_wmem = "4096 16384 8388608";
+    let expected_slow_start = "0";
+
+    check_kernel_param("net.core.rmem_max", expected_rmem_max);
+    check_kernel_param("net.core.wmem_max", expected_wmem_max);
+    check_kernel_param("net.ipv4.tcp_rmem", expected_tcp_rmem);
+    check_kernel_param("net.ipv4.tcp_wmem", expected_tcp_wmem);
+    check_kernel_param("net.ipv4.tcp_slow_start_after_idle", expected_slow_start);
+}
+
 #[cfg(test)]
 mod tests {
     use super::{CryptoHash, NeardCmd, NeardSubCommand, VerifyProofError, VerifyProofSubCommand};

scripts/set_kernel_params.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# This script sets specific sysctl parameters for running a validator.
+# Run it as: sudo ./set_kernel_params.sh
+
+# Increase maximum read and write buffer sizes
+sysctl -w net.core.rmem_max=8388608
+sysctl -w net.core.wmem_max=8388608
+
+# Configure TCP read and write memory parameters
+sysctl -w net.ipv4.tcp_rmem="4096 87380 8388608"
+sysctl -w net.ipv4.tcp_wmem="4096 16384 8388608"
+
+# Disable slow start after idle
+sysctl -w net.ipv4.tcp_slow_start_after_idle=0
+
+echo "Network settings have been updated."