diff --git a/go/util/constants.go b/go/util/constants.go
index c407533a8..61f05898f 100644
--- a/go/util/constants.go
+++ b/go/util/constants.go
@@ -1,5 +1,5 @@
 package util
 
 const (
-	VERSION = "0.64"
+	VERSION = "0.66"
 )
diff --git a/go/weed/benchmark.go b/go/weed/benchmark.go
index 8339913cd..e5cf831c6 100644
--- a/go/weed/benchmark.go
+++ b/go/weed/benchmark.go
@@ -31,6 +31,7 @@ type BenchmarkOptions struct {
 	sequentialRead   *bool
 	collection       *string
 	cpuprofile       *string
+	maxCpu           *int
 	vid2server       map[string]string //cache for vid locations
 }
 
@@ -51,7 +52,8 @@ func init() {
 	b.read = cmdBenchmark.Flag.Bool("read", true, "enable read")
 	b.sequentialRead = cmdBenchmark.Flag.Bool("readSequentially", false, "randomly read by ids from \"-list\" specified file")
 	b.collection = cmdBenchmark.Flag.String("collection", "benchmark", "write data to this collection")
-	b.cpuprofile = cmdBenchmark.Flag.String("cpuprofile", "", "write cpu profile to file")
+	b.cpuprofile = cmdBenchmark.Flag.String("cpuprofile", "", "cpu profile output file")
+	b.maxCpu = cmdBenchmark.Flag.Int("maxCpu", 0, "maximum number of CPUs. 0 means all available CPUs")
 	b.vid2server = make(map[string]string)
 }
 
@@ -59,25 +61,25 @@ var cmdBenchmark = &Command{
 	UsageLine: "benchmark -server=localhost:9333 -c=10 -n=100000",
 	Short:     "benchmark on writing millions of files and read out",
 	Long: `benchmark on an empty weed file system.
-  
+
   Two tests during benchmark:
   1) write lots of small files to the system
   2) read the files out
-  
+
   The file content is mostly zero, but no compression is done.
-    
+
   You can choose to only benchmark read or write.
   During write, the list of uploaded file ids is stored in "-list" specified file.
   You can also use your own list of file ids to run read test.
-  
+
   Write speed and read speed will be collected.
   The numbers are used to get a sense of the system.
   Usually your network or the hard drive is the real bottleneck.
-  
+
   Another thing to watch is whether the volumes are evenly distributed
   to each volume server. Because the 7 more benchmark volumes are randomly distributed
   to servers with free slots, it's highly possible some servers have uneven amount of
-  benchmark volumes. To remedy this, you can use this to grow the benchmark volumes 
+  benchmark volumes. To remedy this, you can use this to grow the benchmark volumes
   before starting the benchmark command:
     http://localhost:9333/vol/grow?collection=benchmark&count=5
 
@@ -100,6 +102,10 @@ func init() {
 
 func runbenchmark(cmd *Command, args []string) bool {
 	fmt.Printf("This is Seaweed File System version %s %s %s\n", util.VERSION, runtime.GOOS, runtime.GOARCH)
+	if *b.maxCpu < 1 {
+		*b.maxCpu = runtime.NumCPU()
+	}
+	runtime.GOMAXPROCS(*b.maxCpu)
 	if *b.cpuprofile != "" {
 		f, err := os.Create(*b.cpuprofile)
 		if err != nil {
@@ -497,9 +503,9 @@ func (l *FakeReader) Read(p []byte) (n int, err error) {
 	} else {
 		n = len(p)
 	}
-	for i := 0; i < n-8; i += 8 {
-		for s := uint(0); s < 8; s++ {
-			p[i] = byte(l.id >> (s * 8))
+	if n >= 8 {
+		for i := 0; i < 8; i++ {
+			p[i] = byte(l.id >> uint(i*8))
 		}
 	}
 	l.size -= int64(n)
diff --git a/go/weed/server.go b/go/weed/server.go
index 6042c22e7..38ccdc137 100644
--- a/go/weed/server.go
+++ b/go/weed/server.go
@@ -32,17 +32,17 @@ func init() {
 var cmdServer = &Command{
 	UsageLine: "server -port=8080 -dir=/tmp -volume.max=5 -ip=server_name",
 	Short:     "start a server, including volume server, and automatically elect a master server",
-	Long: `start both a volume server to provide storage spaces 
+	Long: `start both a volume server to provide storage spaces
   and a master server to provide volume=>location mapping service and sequence number of file ids
-  
+
   This is provided as a convenient way to start both volume server and master server.
   The servers are exactly the same as starting them separately.
 
   So other volume servers can use this embedded master server also.
-  
+
   Optionally, one filer server can be started. Logically, filer servers should not be in a cluster.
   They run with meta data on disk, not shared. So each filer server is different.
-  
+
   `,
 }
 
@@ -73,7 +73,7 @@ var (
 )
 
 func init() {
-	serverOptions.cpuprofile = cmdServer.Flag.String("cpuprofile", "", "write cpu profile to file")
+	serverOptions.cpuprofile = cmdServer.Flag.String("cpuprofile", "", "cpu profile output file")
 	filerOptions.master = cmdServer.Flag.String("filer.master", "", "default to current master server")
 	filerOptions.collection = cmdServer.Flag.String("filer.collection", "", "all data will be stored in this collection")
 	filerOptions.port = cmdServer.Flag.Int("filer.port", 8888, "filer server http listen port")