move to shared

bin/node/bench/src/trie.rs

@@ -179,31 +179,6 @@ impl core::Benchmark for TrieReadBenchmark {
 	fn run(&mut self, mode: Mode) -> std::time::Duration {
 		let mut db = self.database.clone();
 
-		// We clear system cache after db clone but before warmup keys query
-		// This populates system cache with some data unrelated to actual
-		// keys we are quering under benchmark (like what would have happened
-		// in real system that queries random keys).
-		#[cfg(target_os = "linux")] {
-			log::trace!(target: "benchmark-logistics", "Clearing system cache...");
-			std::process::Command::new("echo")
-				.args(&["1", ">", "/proc/sys/vm/drop_caches"])
-				.status()
-				.expect("Failed to execute system cache clear");
-			log::trace!(target: "benchmark-logistics", "Clearing system cache done!");
-		}
-
-		#[cfg(target_os = "macos")] {
-			log::trace!(target: "benchmark-logistics", "Clearing system cache...");
-			std::process::Command::new("sync")
-				.status()
-				.expect("Failed to execute sync");
-			std::process::Command::new("sudo")
-				.arg("purge")
-				.status()
-				.expect("Failed to execute sudo purge");
-			log::trace!(target: "benchmark-logistics", "Clearing system cache done!");
-		}
-
 		let storage: Arc<dyn sp_state_machine::Storage<sp_core::Blake2Hasher>> =
 			Arc::new(Storage(db.open(self.database_type)));
 

bin/node/testing/src/bench.rs

@@ -88,6 +88,33 @@ impl BenchPair {
 	}
 }
 
+/// Drop system cache.
+/// 
+/// Will panic if cache drop is impossbile.
+pub fn drop_system_cache() {
+	#[cfg(target_os = "linux")] {
+		log::trace!(target: "bench-logistics", "Clearing system cache...");
+		std::process::Command::new("echo")
+			.args(&["1", ">", "/proc/sys/vm/drop_caches", "2>", "/dev/null"])
+			.output()
+			.expect("Failed to execute system cache clear");
+		log::trace!(target: "bench-logistics", "Clearing system cache done!");
+	}
+
+	#[cfg(target_os = "macos")] {
+		log::trace!(target: "bench-logistics", "Clearing system cache...");
+		std::process::Command::new("sync")
+			.output()
+			.expect("Failed to execute sync");
+		if let Err(err) = std::process::Command::new("purge").output() {
+			log::error!("purge error {:?}: ", err);
+			panic!("Could not clear system cache. Run under sudo?");
+		}
+		log::trace!(target: "bench-logistics", "Clearing system cache done!");
+	}
+
+}
+
 /// Pre-initialized benchmarking database.
 ///
 /// This is prepared database with genesis and keyring
@@ -124,6 +151,13 @@ impl Clone for BenchDb {
 			&fs_extra::dir::CopyOptions::new(),
 		).expect("Copy of seed database is ok");
 
+		// We clear system cache after db clone but before any warmups.
+		// This populates system cache with some data unrelated to actual
+		// data we will be quering further under benchmark (like what 
+		// would have happened in real system that queries random entries 
+		// from database).
+		drop_system_cache();
+
 		BenchDb { keyring, directory_guard: Guard(dir), database_type }
 	}
 }