cmd, consensus: add option to disable mmap for DAG caches/datasets (#20484)

* cmd, consensus: add option to disable mmap for DAG caches/datasets

* consensus: add benchmarks for mmap with/with lock

eth/backend.go

@@ -266,12 +266,14 @@ func CreateConsensusEngine(ctx *node.ServiceContext, chainConfig *params.ChainCo
 		return ethash.NewShared()
 	default:
 		engine := ethash.New(ethash.Config{
-			CacheDir:       ctx.ResolvePath(config.CacheDir),
-			CachesInMem:    config.CachesInMem,
-			CachesOnDisk:   config.CachesOnDisk,
-			DatasetDir:     config.DatasetDir,
-			DatasetsInMem:  config.DatasetsInMem,
-			DatasetsOnDisk: config.DatasetsOnDisk,
+			CacheDir:         ctx.ResolvePath(config.CacheDir),
+			CachesInMem:      config.CachesInMem,
+			CachesOnDisk:     config.CachesOnDisk,
+			CachesLockMmap:   config.CachesLockMmap,
+			DatasetDir:       config.DatasetDir,
+			DatasetsInMem:    config.DatasetsInMem,
+			DatasetsOnDisk:   config.DatasetsOnDisk,
+			DatasetsLockMmap: config.DatasetsLockMmap,
 		}, notify, noverify)
 		engine.SetThreads(-1) // Disable CPU mining
 		return engine

eth/config.go

@@ -37,11 +37,13 @@ import (
 var DefaultConfig = Config{
 	SyncMode: downloader.FastSync,
 	Ethash: ethash.Config{
-		CacheDir:       "ethash",
-		CachesInMem:    2,
-		CachesOnDisk:   3,
-		DatasetsInMem:  1,
-		DatasetsOnDisk: 2,
+		CacheDir:         "ethash",
+		CachesInMem:      2,
+		CachesOnDisk:     3,
+		CachesLockMmap:   false,
+		DatasetsInMem:    1,
+		DatasetsOnDisk:   2,
+		DatasetsLockMmap: false,
 	},
 	NetworkId:          1,
 	LightPeers:         100,