[CI] Disable runtime logging for benchmarks

.gitlab/pipeline/short-benchmarks.yml

@@ -15,6 +15,7 @@ short-benchmark-polkadot: &short-bench
       artifacts: true
   variables:
     RUNTIME: polkadot
+    RUNTIME_LOG: off
   tags:
     - benchmark
   script:
@@ -42,6 +43,7 @@ short-benchmark-westend:
       artifacts: true
   variables:
     RUNTIME_CHAIN: benchmarked-runtime-chain
+    RUNTIME_LOG: off
   tags:
     - benchmark
   script:

substrate/primitives/io/src/lib.rs

@@ -1553,6 +1553,9 @@ pub trait PanicHandler {
 	}
 }
 
+/// Set a different log level for the runtime instead of using the one from the host.
+pub const RUNTIME_LOG_ENV: &str = "RUNTIME_LOG";
+
 /// Interface that provides functions for logging from within the runtime.
 #[runtime_interface]
 pub trait Logging {
@@ -1568,8 +1571,16 @@ pub trait Logging {
 		}
 	}
 
-	/// Returns the max log level used by the host.
+	/// Returns the max log level for the runtime.
+	///
+	/// Uses the host as default log level but can be overwritten with [`RUNTIME_LOG_ENV`].
 	fn max_level() -> LogLevelFilter {
+		if let Ok(level) = std::env::var(RUNTIME_LOG_ENV) {
+			if let Ok(level) = level.parse::<log::LevelFilter>() {
+				return level.into()
+			}
+		}
+
 		log::max_level().into()
 	}
 }