iperf: Fix benchmark for low b.N values and parallelization enabled.

PiperOrigin-RevId: 785546900

Author: EtiennePerot

test/benchmarks/tools/iperf.go

@@ -35,7 +35,8 @@ func (i *Iperf) MakeCmd(host string, port int) []string {
 	cmd = append(cmd, "--len", "128K") // Length of data buffer per request.
 	n := i.Num
 	if i.Parallel > 0 {
-		n = i.Num / i.Parallel
+		// Must be at least 1, otherwise iperf will complain about having nothing to transmit.
+		n = max(i.Num/i.Parallel, 1)
 	}
 	cmd = append(cmd, "--num", fmt.Sprintf("%dK", n)) // Number of requests to send.
 	cmd = append(cmd, "--client", host)