Improve throttling and take input as bits/s instead of bytes/s (#136)

* Take rate input as bits/s

* Update README.md

* Fix throttling to be as precise as possible.

* Minor doc fix.

* Update README.md

README.md

@@ -217,9 +217,9 @@ In this mode, Ethr client can only talk to an Ethr server.
 		Run in client mode and connect to <server>.
 		Server is specified using name, FQDN or IP address.
 	-b <rate>
-		Bytes to send per second (format: <num>[KB | MB | GB])
+		Transmit only Bits per second (format: <num>[K | M | G])
 		Only valid for Bandwidth tests. Default: 0 - Unlimited
-		Examples: 100 (100B/s or 800bits/s), 1MB (1MB/s or 8Mbits/s).
+		Examples: 100 (100bits/s), 1M (1Mbits/s).
 	-cport <number>
 		Use specified local port number in client for TCP & UDP tests.
 		Default: 0 - Ephemeral Port

client.go

@@ -259,9 +259,6 @@ func runTCPBandwidthTestHandler(test *ethrTest, conn net.Conn, wg *sync.WaitGrou
 	ui.printMsg("[%3d] local %s port %s connected to %s port %s",
 		ec.fd, lserver, lport, rserver, rport)
 	size := test.clientParam.BufferSize
-	if test.clientParam.BwRate > 0 && uint64(size) > test.clientParam.BwRate {
-		size = uint32(test.clientParam.BwRate)
-	}
 	buff := make([]byte, size)
 	for i := uint32(0); i < size; i++ {
 		buff[i] = byte(i)
@@ -959,9 +956,6 @@ func runUDPBandwidthAndPpsTest(test *ethrTest) {
 	for th := uint32(0); th < test.clientParam.NumThreads; th++ {
 		go func(th uint32) {
 			size := test.clientParam.BufferSize
-			if test.clientParam.BwRate > 0 && uint64(size) > test.clientParam.BwRate {
-				size = uint32(test.clientParam.BwRate)
-			}
 			buff := make([]byte, size)
 			conn, err := ethrDialInc(UDP, test.dialAddr, uint16(th))
 			if err != nil {

ethr.go

@@ -201,6 +201,14 @@ func main() {
 		bwRate := uint64(0)
 		if *bwRateStr != "" {
 			bwRate = unitToNumber(*bwRateStr)
+			bwRate /= 8
+		}
+
+		// Adjust the numbers so that data can be transfered in equal units.
+		if bwRate > 0 {
+			factor := (bwRate + bufLen - 1) / bufLen
+			bufLen = bwRate / factor
+			bwRate = bufLen * factor
 		}
 
 		//
@@ -503,7 +511,7 @@ func printGapUsage() {
 
 func printBufLenUsage() {
 	printFlagUsage("l", "<length>",
-		"Length of buffer to use (format: <num>[KB | MB | GB])",
+		"Length of buffer (in Bytes) to use (format: <num>[KB | MB | GB])",
 		"Only valid for Bandwidth tests. Max 1GB.",
 		"Default: 16KB")
 }
@@ -552,9 +560,9 @@ func printToSUsage() {
 
 func printBwRateUsage() {
 	printFlagUsage("b", "<rate>",
-		"Bytes to send per second (format: <num>[KB | MB | GB])",
+		"Transmit only Bits per second (format: <num>[K | M | G])",
 		"Only valid for Bandwidth tests. Default: 0 - Unlimited",
-		"Examples: 100 (100B/s or 800bits/s), 1MB (1MB/s or 8Mbits/s).")
+		"Examples: 100 (100bits/s), 1M (1Mbits/s).")
 }
 
 func printCPortUsage() {

server.go

@@ -145,9 +145,6 @@ func srvrHandleNewTcpConn(conn net.Conn) {
 
 func srvrRunTCPBandwidthTest(test *ethrTest, clientParam EthrClientParam, conn net.Conn) {
 	size := clientParam.BufferSize
-	if clientParam.BwRate > 0 && uint64(size) > clientParam.BwRate {
-		size = uint32(clientParam.BwRate)
-	}
 	buff := make([]byte, size)
 	for i := uint32(0); i < size; i++ {
 		buff[i] = byte(i)