[stable2603] Backport #11069 (#11074)

Backport #11069 into `stable2603` from sigurpol.

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[documentation](https://github.com/paritytech/polkadot-sdk/blob/master/docs/BACKPORT.md)
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Co-authored-by: Paolo La Camera <paolo@parity.io>
Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Bastian Köcher <git@kchr.de>

Author: 4 people

Cargo.lock

@@ -0,0 +1,11 @@
+title: 'frame-omni-bencher: enable jemalloc-allocator'
+doc:
+- audience: Runtime Dev
+  description: |-
+    Fix huge benchmark regression for storage-heavy extrinsics, enabling jemalloc-allocator via polkadot-jemalloc-shim for omni-bencher, marked as optional in the scope of PR #10590.
+    Revert also the dummy write/read workaround at the end of commit_db() introduced by #10947.
+crates:
+- name: frame-omni-bencher
+  bump: patch
+- name: frame-benchmarking
+  bump: patch

prdoc/pr_11069.prdoc

@@ -290,19 +290,6 @@ pub trait Benchmarking {
 	/// Commit pending storage changes to the trie database and clear the database cache.
 	fn commit_db(&mut self) {
 		self.commit();
-
-		// Warmup the memory allocator after bulk deallocation.
-		// After draining the overlay with many entries, the first new allocation can trigger memory
-		// defragmentation. The warmup key is whitelisted so these operations don't appear in
-		// benchmark results.
-		const WARMUP_KEY: &[u8] = b":benchmark_warmup:";
-		let mut whitelist = self.get_whitelist();
-		if !whitelist.iter().any(|k| k.key == WARMUP_KEY) {
-			whitelist.push(WARMUP_KEY.to_vec().into());
-			self.set_whitelist(whitelist);
-		}
-		self.place_storage(WARMUP_KEY.to_vec(), Some(vec![0u8; 32]));
-		self.place_storage(WARMUP_KEY.to_vec(), None);
 	}
 
 	/// Get the read/write count.

substrate/frame/benchmarking/src/utils.rs

@@ -15,11 +15,16 @@ workspace = true
 clap = { features = ["derive"], workspace = true }
 cumulus-primitives-proof-size-hostfunction = { workspace = true, default-features = true }
 frame-benchmarking-cli = { workspace = true }
+polkadot-jemalloc-shim = { workspace = true }
 sc-cli = { workspace = true, default-features = true }
 sp-runtime = { workspace = true, default-features = true }
 sp-statement-store = { workspace = true, default-features = true }
 tracing-subscriber = { workspace = true }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+# Jemalloc as global allocator prevents huge benchmark regression for storage-heavy extrinsics.
+polkadot-jemalloc-shim = { workspace = true, features = ["jemalloc-allocator"] }
+
 [dev-dependencies]
 assert_cmd = { workspace = true }
 cumulus-test-runtime = { workspace = true }