refactor(test): Clarify iperf3 setting

Some comments were confusing, since their descriptions were vague or
wrong. To make it easy to understand what tests do, clarify iperf3
settings (server or client mode and on host or guest).

Signed-off-by: Takahiro Itazuri <[email protected]>

Author: zulinx86

tests/integration_tests/functional/test_rate_limiter.py

@@ -154,7 +154,7 @@ def test_rx_rate_limiting_cpu_load(test_microvm_with_api, network_config):
     test_microvm.start()
 
     # Start iperf server on guest.
-    _start_iperf_on_guest(test_microvm, guest_ip)
+    _start_iperf_server_on_guest(test_microvm, guest_ip)
 
     # Run iperf client sending UDP traffic.
     iperf_cmd = "{} {} -u -c {} -b 1000000000 -t{} -f KBytes".format(
@@ -177,13 +177,13 @@ def test_rx_rate_limiting_cpu_load(test_microvm_with_api, network_config):
         threshold=20,
     )
     with cpu_load_monitor:
-        _run_local_iperf(iperf_cmd)
+        _run_iperf_on_host(iperf_cmd)
 
 
 def _check_tx_rate_limiting(test_microvm, guest_ips, host_ips):
     """Check that the transmit rate is within expectations."""
-    # Start iperf on the host as this is the tx rate limiting test.
-    _start_local_iperf(test_microvm.jailer.netns_cmd_prefix())
+    # Start iperf server on the host as this is the tx rate limiting test.
+    _start_iperf_server_on_host(test_microvm.jailer.netns_cmd_prefix())
 
     # First step: get the transfer rate when no rate limiting is enabled.
     # We are receiving the result in KBytes from iperf.
@@ -226,8 +226,8 @@ def _check_tx_rate_limiting(test_microvm, guest_ips, host_ips):
 
 def _check_rx_rate_limiting(test_microvm, guest_ips):
     """Check that the receiving rate is within expectations."""
-    # Start iperf on guest.
-    _start_iperf_on_guest(test_microvm, guest_ips[0])
+    # Start iperf server on guest.
+    _start_iperf_server_on_guest(test_microvm, guest_ips[0])
 
     # First step: get the transfer rate when no rate limiting is enabled.
     # We are receiving the result in KBytes from iperf.
@@ -251,7 +251,7 @@ def _check_rx_rate_limiting(test_microvm, guest_ips):
 
     # Third step: get the number of bytes when rate limiting is on and there is
     # an initial burst size from where to consume.
-    print("Run guest TX iperf with exact burst size")
+    print("Run guest RX iperf with exact burst size")
     # Use iperf to obtain the bandwidth when there is burst to consume from,
     # send exactly BURST_SIZE packets.
     iperf_cmd = "{} {} -c {} -n {} -f KBytes -w {} -N".format(
@@ -261,7 +261,7 @@ def _check_rx_rate_limiting(test_microvm, guest_ips):
         BURST_SIZE,
         IPERF_TCP_WINDOW,
     )
-    iperf_out = _run_local_iperf(iperf_cmd)
+    iperf_out = _run_iperf_on_host(iperf_cmd)
     print(iperf_out)
     _, burst_kbps = _process_iperf_output(iperf_out)
     print("RX burst_kbps: {}".format(burst_kbps))
@@ -395,7 +395,7 @@ def _get_rx_bandwidth_with_duration(test_microvm, guest_ip, duration):
         duration,
         IPERF_TCP_WINDOW,
     )
-    iperf_out = _run_local_iperf(iperf_cmd)
+    iperf_out = _run_iperf_on_host(iperf_cmd)
     print(iperf_out)
 
     _, observed_kbps = _process_iperf_output(iperf_out)
@@ -420,7 +420,7 @@ def _patch_iface_bw(test_microvm, iface_id, rx_or_tx, new_bucket_size, new_refil
     assert test_microvm.api_session.is_status_no_content(resp.status_code)
 
 
-def _start_iperf_on_guest(test_microvm, hostname):
+def _start_iperf_server_on_guest(test_microvm, hostname):
     """Start iperf in server mode through an SSH connection."""
     test_microvm.ssh_config["hostname"] = hostname
 
@@ -441,7 +441,7 @@ def _run_iperf_on_guest(test_microvm, iperf_cmd, hostname):
     return out
 
 
-def _start_local_iperf(netns_cmd_prefix):
+def _start_iperf_server_on_host(netns_cmd_prefix):
     """Start iperf in server mode after killing any leftover iperf daemon."""
     iperf_cmd = "pkill {}\n".format(IPERF_BINARY)
 
@@ -457,7 +457,7 @@ def _start_local_iperf(netns_cmd_prefix):
     time.sleep(1)
 
 
-def _run_local_iperf(iperf_cmd):
+def _run_iperf_on_host(iperf_cmd):
     """Execute a client related iperf command locally."""
     code, stdout, stderr = utils.run_cmd(iperf_cmd)
     assert code == 0, f"stdout: {stdout}\nstderr: {stderr}"