cmd, core/state: allow configurable trie cache generations

cmd/utils/flags.go

@@ -141,11 +141,6 @@ var (
 		Usage: "Document Root for HTTPClient file scheme",
 		Value: DirectoryString{homeDir()},
 	}
-	CacheFlag = cli.IntFlag{
-		Name:  "cache",
-		Usage: "Megabytes of memory allocated to internal caching (min 16MB / database forced)",
-		Value: 128,
-	}
 	FastSyncFlag = cli.BoolFlag{
 		Name:  "fast",
 		Usage: "Enable fast syncing through state downloads",
@@ -154,6 +149,17 @@ var (
 		Name:  "lightkdf",
 		Usage: "Reduce key-derivation RAM & CPU usage at some expense of KDF strength",
 	}
+	// Performance tuning settings
+	CacheFlag = cli.IntFlag{
+		Name:  "cache",
+		Usage: "Megabytes of memory allocated to internal caching (min 16MB / database forced)",
+		Value: 128,
+	}
+	TrieCacheGenFlag = cli.IntFlag{
+		Name:  "trie-cache-gens",
+		Usage: "Number of trie node generations to keep in memory",
+		Value: int(state.MaxTrieCacheGen),
+	}
 	// Fork settings
 	SupportDAOFork = cli.BoolFlag{
 		Name:  "support-dao-fork",
@@ -721,6 +727,10 @@ func RegisterEthService(ctx *cli.Context, stack *node.Node, extra []byte) {
 		}
 		ethConf.PowTest = true
 	}
+	// Override any global options pertaining to the Ethereum protocol
+	if gen := ctx.GlobalInt(TrieCacheGenFlag.Name); gen > 0 {
+		state.MaxTrieCacheGen = uint16(gen)
+	}
 
 	if err := stack.Register(func(ctx *node.ServiceContext) (node.Service, error) {
 		return eth.New(ctx, ethConf)