run node bandwidth tests using iperf2 and collecting more detailed information

This commit is contained in:
Matthew Fenwick 2021-01-21 05:50:17 -05:00
parent 5856883274
commit 069ec05037
3 changed files with 351 additions and 121 deletions

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@ -96,6 +96,7 @@ go_library(
"//vendor/github.com/miekg/dns:go_default_library", "//vendor/github.com/miekg/dns:go_default_library",
"//vendor/github.com/onsi/ginkgo:go_default_library", "//vendor/github.com/onsi/ginkgo:go_default_library",
"//vendor/github.com/onsi/gomega:go_default_library", "//vendor/github.com/onsi/gomega:go_default_library",
"//vendor/github.com/pkg/errors:go_default_library",
"//vendor/google.golang.org/api/compute/v1:go_default_library", "//vendor/google.golang.org/api/compute/v1:go_default_library",
"//vendor/k8s.io/utils/net:go_default_library", "//vendor/k8s.io/utils/net:go_default_library",
], ],

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@ -18,145 +18,311 @@ package network
// Tests network performance using iperf or other containers. // Tests network performance using iperf or other containers.
import ( import (
"context"
"fmt" "fmt"
discoveryv1beta1 "k8s.io/api/discovery/v1beta1"
"time" "time"
"github.com/onsi/ginkgo" "github.com/onsi/ginkgo"
appsv1 "k8s.io/api/apps/v1"
v1 "k8s.io/api/core/v1" v1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/util/wait"
clientset "k8s.io/client-go/kubernetes"
"k8s.io/kubernetes/test/e2e/framework" "k8s.io/kubernetes/test/e2e/framework"
e2edeployment "k8s.io/kubernetes/test/e2e/framework/deployment"
e2enode "k8s.io/kubernetes/test/e2e/framework/node" e2enode "k8s.io/kubernetes/test/e2e/framework/node"
e2eservice "k8s.io/kubernetes/test/e2e/framework/service"
imageutils "k8s.io/kubernetes/test/utils/image" imageutils "k8s.io/kubernetes/test/utils/image"
) )
const ( const (
// empirically derived as a baseline for expectations from running this test using kube-up.sh. // use this timeout for larger clusters
gceBandwidthBitsEstimate = int64(30000000000) largeClusterTimeout = 400 * time.Second
// on 4 node clusters, we found this test passes very quickly, generally in less then 100 seconds. // iperf2BaselineBandwidthMegabytesPerSecond sets a baseline for iperf2 bandwidth of 90 MB/s
smallClusterTimeout = 200 * time.Second iperf2BaselineBandwidthMegabytesPerSecond = 90
// iperf2Port selects an arbitrary, unique port to run iperf2's client and server on
iperf2Port = 6789
// labelKey is used as a key for selectors
labelKey = "app"
// clientLabelValue is used as a value for iperf2 client selectors
clientLabelValue = "iperf2-client"
// serverLabelValue is used as a value for iperf2 server selectors
serverLabelValue = "iperf2-server"
// serverServiceName defines the service name used for the iperf2 server
serverServiceName = "iperf2-server"
) )
// Declared as Flakey since it has not been proven to run in parallel on small nodes or slow networks in CI func iperf2ServerDeployment(client clientset.Interface, namespace string, isIPV6 bool) (*appsv1.Deployment, error) {
var _ = SIGDescribe("Networking IPerf [Experimental] [Slow] [Feature:Networking-Performance]", func() { framework.Logf("deploying iperf2 server")
one := int64(1)
f := framework.NewDefaultFramework("network-perf") replicas := int32(1)
labels := map[string]string{labelKey: serverLabelValue}
// A few simple bandwidth tests which are capped by nodes. args := []string{
// TODO replace the 1 with the scale option implementation "-s",
// TODO: Make this a function parameter, once we distribute iperf endpoints, possibly via session affinity. "-p",
numClient := 1 fmt.Sprintf("%d", iperf2Port),
numServer := 1
maxBandwidthBits := gceBandwidthBitsEstimate
familyStr := ""
if framework.TestContext.ClusterIsIPv6() {
familyStr = "-V "
} }
if isIPV6 {
ginkgo.It(fmt.Sprintf("should transfer ~ 1GB onto the service endpoint %v servers (maximum of %v clients)", numServer, numClient), func() { args = append(args, "-V")
nodes, err := e2enode.GetReadySchedulableNodes(f.ClientSet) }
framework.ExpectNoError(err) deploymentSpec := &appsv1.Deployment{
totalPods := len(nodes.Items) ObjectMeta: metav1.ObjectMeta{
// for a single service, we expect to divide bandwidth between the network. Very crude estimate. Name: "iperf2-server-deployment",
expectedBandwidth := int(float64(maxBandwidthBits) / float64(totalPods)) Labels: labels,
appName := "iperf-e2e" },
_, err = e2eservice.CreateServiceForSimpleAppWithPods( Spec: appsv1.DeploymentSpec{
f.ClientSet, Replicas: &replicas,
8001, Selector: &metav1.LabelSelector{
8002, MatchLabels: labels,
f.Namespace.Name,
appName,
func(n v1.Node) v1.PodSpec {
return v1.PodSpec{
Containers: []v1.Container{{
Name: "iperf-server",
Image: imageutils.GetE2EImage(imageutils.Agnhost),
Command: []string{"/bin/sh"},
Args: []string{
"-c",
"/usr/local/bin/iperf " + familyStr + "-s -p 8001 ",
},
Ports: []v1.ContainerPort{{ContainerPort: 8001}},
}},
NodeName: n.Name,
RestartPolicy: v1.RestartPolicyOnFailure,
}
}, },
// this will be used to generate the -service name which all iperf clients point at. Template: v1.PodTemplateSpec{
numServer, // Generally should be 1 server unless we do affinity or use a version of iperf that supports LB ObjectMeta: metav1.ObjectMeta{
true, // Make sure we wait, otherwise all the clients will die and need to restart. Labels: labels,
) },
Spec: v1.PodSpec{
if err != nil { TerminationGracePeriodSeconds: &one,
framework.Failf("Fatal error waiting for iperf server endpoint : %v", err)
}
iperfClientPodLabels := e2enode.CreatePodsPerNodeForSimpleApp(
f.ClientSet,
f.Namespace.Name,
"iperf-e2e-cli",
func(n v1.Node) v1.PodSpec {
return v1.PodSpec{
Containers: []v1.Container{ Containers: []v1.Container{
{ {
Name: "iperf-client", Name: "iperf2-server",
Image: imageutils.GetE2EImage(imageutils.Agnhost), Image: imageutils.GetE2EImage(imageutils.Agnhost),
Command: []string{"/bin/sh"}, Command: []string{"iperf"},
Args: []string{ Args: args,
"-c", Ports: []v1.ContainerPort{
"/usr/local/bin/iperf " + familyStr + "-c service-for-" + appName + " -p 8002 --reportstyle C && sleep 5", {
ContainerPort: iperf2Port,
Protocol: v1.ProtocolTCP,
},
}, },
}, },
}, },
RestartPolicy: v1.RestartPolicyOnFailure, // let them successfully die. },
},
},
}
deployment, err := client.AppsV1().Deployments(namespace).Create(context.TODO(), deploymentSpec, metav1.CreateOptions{})
if err != nil {
return nil, fmt.Errorf("deployment %q Create API error: %v", deploymentSpec.Name, err)
}
framework.Logf("Waiting for deployment %q to complete", deploymentSpec.Name)
err = e2edeployment.WaitForDeploymentComplete(client, deployment)
if err != nil {
return nil, fmt.Errorf("deployment %q failed to complete: %v", deploymentSpec.Name, err)
}
return deployment, nil
}
func iperf2ServerService(client clientset.Interface, namespace string) (*v1.Service, error) {
service := &v1.Service{
ObjectMeta: metav1.ObjectMeta{Name: serverServiceName},
Spec: v1.ServiceSpec{
Selector: map[string]string{
labelKey: serverLabelValue,
},
Ports: []v1.ServicePort{
{Protocol: v1.ProtocolTCP, Port: iperf2Port},
},
},
}
return client.CoreV1().Services(namespace).Create(context.TODO(), service, metav1.CreateOptions{})
}
func iperf2ClientDaemonSet(client clientset.Interface, namespace string) (*appsv1.DaemonSet, error) {
one := int64(1)
labels := map[string]string{labelKey: clientLabelValue}
spec := &appsv1.DaemonSet{
ObjectMeta: metav1.ObjectMeta{
Name: "iperf2-clients",
Labels: labels,
},
Spec: appsv1.DaemonSetSpec{
Selector: &metav1.LabelSelector{
MatchLabels: labels,
},
Template: v1.PodTemplateSpec{
ObjectMeta: metav1.ObjectMeta{
Labels: labels,
},
Spec: v1.PodSpec{
Containers: []v1.Container{
{
Name: "iperf2-client",
Image: imageutils.GetE2EImage(imageutils.Agnhost),
Command: []string{"/agnhost"},
Args: []string{"pause"},
},
},
TerminationGracePeriodSeconds: &one,
},
},
},
Status: appsv1.DaemonSetStatus{},
}
ds, err := client.AppsV1().DaemonSets(namespace).Create(context.TODO(), spec, metav1.CreateOptions{})
if err != nil {
return nil, fmt.Errorf("daemonset %s Create API error: %v", spec.Name, err)
}
return ds, nil
}
// Test summary:
// This test uses iperf2 to obtain bandwidth data between nodes in the cluster, providing a coarse measure
// of the health of the cluster network. The test runs two sets of pods:
// 1. an iperf2 server on a single node
// 2. a daemonset of iperf2 clients
// The test then iterates through the clients, one by one, running iperf2 from each of them to transfer
// data to the server and back for ten seconds, after which the results are collected and parsed.
// Thus, if your cluster has 10 nodes, then 10 test runs are performed.
// Note: a more complete test could run this scenario with a daemonset of servers as well; however, this
// would require n^2 tests, n^2 time, and n^2 network resources which quickly become prohibitively large
// as the cluster size increases.
// Finally, after collecting all data, the results are analyzed and tabulated.
var _ = SIGDescribe("Networking IPerf2 [Feature:Networking-Performance]", func() {
// this test runs iperf2: one pod as a server, and a daemonset of clients
f := framework.NewDefaultFramework("network-perf")
ginkgo.It(fmt.Sprintf("should run iperf2"), func() {
readySchedulableNodes, err := e2enode.GetReadySchedulableNodes(f.ClientSet)
framework.ExpectNoError(err)
familyStr := ""
if framework.TestContext.ClusterIsIPv6() {
familyStr = "-V "
}
serverPodsListOptions := metav1.ListOptions{
LabelSelector: fmt.Sprintf("%s=%s", labelKey, serverLabelValue),
}
// Step 1: set up iperf2 server -- a single pod on any node
_, err = iperf2ServerDeployment(f.ClientSet, f.Namespace.Name, framework.TestContext.ClusterIsIPv6())
framework.ExpectNoError(err, "deploy iperf2 server deployment")
_, err = iperf2ServerService(f.ClientSet, f.Namespace.Name)
framework.ExpectNoError(err, "deploy iperf2 server service")
// Step 2: set up iperf2 client daemonset
// initially, the clients don't do anything -- they simply pause until they're called
_, err = iperf2ClientDaemonSet(f.ClientSet, f.Namespace.Name)
framework.ExpectNoError(err, "deploy iperf2 client daemonset")
// Make sure the server is ready to go
framework.Logf("waiting for iperf2 server endpoints")
err = wait.Poll(2*time.Second, largeClusterTimeout, func() (done bool, err error) {
listOptions := metav1.ListOptions{LabelSelector: fmt.Sprintf("%s=%s", discoveryv1beta1.LabelServiceName, serverServiceName)}
esList, err := f.ClientSet.DiscoveryV1beta1().EndpointSlices(f.Namespace.Name).List(context.TODO(), listOptions)
framework.ExpectNoError(err, "Error fetching EndpointSlice for Service %s/%s", f.Namespace.Name, serverServiceName)
if len(esList.Items) == 0 {
framework.Logf("EndpointSlice for Service %s/%s not found", f.Namespace.Name, serverServiceName)
return false, nil
}
return true, nil
})
framework.ExpectNoError(err, "unable to wait for endpoints for the iperf service")
framework.Logf("found iperf2 server endpoints")
clientPodsListOptions := metav1.ListOptions{
LabelSelector: fmt.Sprintf("%s=%s", labelKey, clientLabelValue),
}
framework.Logf("waiting for client pods to be running")
var clientPodList *v1.PodList
err = wait.Poll(2*time.Second, largeClusterTimeout, func() (done bool, err error) {
clientPodList, err = f.ClientSet.CoreV1().Pods(f.Namespace.Name).List(context.TODO(), clientPodsListOptions)
if err != nil {
return false, err
}
if len(clientPodList.Items) < len(readySchedulableNodes.Items) {
return false, nil
}
for _, pod := range clientPodList.Items {
if pod.Status.Phase != v1.PodRunning {
return false, nil
} }
}, }
numClient, return true, nil
) })
expectedCli := numClient framework.ExpectNoError(err, "unable to wait for client pods to come up")
if len(nodes.Items) < expectedCli { framework.Logf("all client pods are ready: %d pods", len(clientPodList.Items))
expectedCli = len(nodes.Items)
// Get a reference to the server pod for later
serverPodList, err := f.ClientSet.CoreV1().Pods(f.Namespace.Name).List(context.TODO(), serverPodsListOptions)
framework.ExpectNoError(err)
if len(serverPodList.Items) != 1 {
framework.Failf("expected 1 server pod, found %d", len(serverPodList.Items))
}
serverPod := serverPodList.Items[0]
framework.Logf("server pod phase %s", serverPod.Status.Phase)
for i, condition := range serverPod.Status.Conditions {
framework.Logf("server pod condition %d: %+v", i, condition)
}
for i, cont := range serverPod.Status.ContainerStatuses {
framework.Logf("server pod container status %d: %+v", i, cont)
} }
framework.Logf("Reading all perf results to stdout.") framework.Logf("found %d matching client pods", len(clientPodList.Items))
framework.Logf("date,cli,cliPort,server,serverPort,id,interval,transferBits,bandwidthBits")
// Extra 1/10 second per client. nodeResults := &IPerf2NodeToNodeCSVResults{
iperfTimeout := smallClusterTimeout + (time.Duration(expectedCli/10) * time.Second) ServerNode: serverPod.Spec.NodeName,
iperfResults := &IPerfResults{} Results: map[string]*IPerf2EnhancedCSVResults{},
iperfClusterVerification := f.NewClusterVerification(
f.Namespace,
framework.PodStateVerification{
Selectors: iperfClientPodLabels,
ValidPhases: []v1.PodPhase{v1.PodSucceeded},
},
)
pods, err2 := iperfClusterVerification.WaitFor(expectedCli, iperfTimeout)
if err2 != nil {
framework.Failf("Error in wait...")
} else if len(pods) < expectedCli {
framework.Failf("IPerf restuls : Only got %v out of %v, after waiting %v", len(pods), expectedCli, iperfTimeout)
} else {
// For each builds up a collection of IPerfRecords
iperfClusterVerification.ForEach(
func(p v1.Pod) {
resultS, err := framework.LookForStringInLog(f.Namespace.Name, p.Name, "iperf-client", "0-", 1*time.Second)
if err == nil {
framework.Logf(resultS)
iperfResults.Add(NewIPerf(resultS))
} else {
framework.Failf("Unexpected error, %v when running forEach on the pods.", err)
}
})
} }
fmt.Println("[begin] Node,Bandwidth CSV")
fmt.Println(iperfResults.ToTSV())
fmt.Println("[end] Node,Bandwidth CSV")
for ipClient, bandwidth := range iperfResults.BandwidthMap { // Step 3: iterate through the client pods one by one, running iperf2 in client mode to transfer
framework.Logf("%v had bandwidth %v. Ratio to expected (%v) was %f", ipClient, bandwidth, expectedBandwidth, float64(bandwidth)/float64(expectedBandwidth)) // data to the server and back and measure bandwidth
for _, pod := range clientPodList.Items {
podName := pod.Name
nodeName := pod.Spec.NodeName
iperfVersion := f.ExecShellInPod(podName, "iperf -v || true")
framework.Logf("iperf version: %s", iperfVersion)
for try := 0; ; try++ {
/* iperf2 command parameters:
* -e: use enhanced reporting giving more tcp/udp and traffic information
* -p %d: server port to connect to
* --reportstyle C: report as Comma-Separated Values
* -i 1: seconds between periodic bandwidth reports
* -c %s: run in client mode, connecting to <host>
*/
command := fmt.Sprintf(`iperf %s -e -p %d --reportstyle C -i 1 -c %s && sleep 5`, familyStr, iperf2Port, serverServiceName)
framework.Logf("attempting to run command '%s' in client pod %s (node %s)", command, podName, nodeName)
output := f.ExecShellInPod(podName, command)
framework.Logf("output from exec on client pod %s (node %s): \n%s\n", podName, nodeName, output)
results, err := ParseIPerf2EnhancedResultsFromCSV(output)
if err == nil {
nodeResults.Results[nodeName] = results
break
} else if try == 2 {
framework.ExpectNoError(err, "unable to parse iperf2 output from client pod %s (node %s)", pod.Name, nodeName)
} else {
framework.Logf("Retrying: IPerf run failed: %+v", err)
}
}
}
// Step 4: after collecting all the client<->server data, compile and present the results
/*
Example output:
Dec 22 07:52:41.102: INFO: From To Bandwidth (MB/s)
Dec 22 07:52:41.102: INFO: three-node-ipv6-worker three-node-ipv6-worker2 2381
Dec 22 07:52:41.102: INFO: three-node-ipv6-worker2 three-node-ipv6-worker2 2214
Dec 22 07:52:41.102: INFO: three-node-ipv6-worker3 three-node-ipv6-worker2 3123
*/
framework.Logf("%35s%35s%20s", "From", "To", "Bandwidth (MB/s)")
for nodeFrom, results := range nodeResults.Results {
framework.Logf("%35s%35s%20d", nodeFrom, nodeResults.ServerNode, results.Total.bandwidthMB())
}
for clientNode, results := range nodeResults.Results {
megabytesPerSecond := results.Total.bandwidthMB()
if megabytesPerSecond < iperf2BaselineBandwidthMegabytesPerSecond {
framework.Failf("iperf2 MB/s received below baseline of %d for client %s to server %s: %d", iperf2BaselineBandwidthMegabytesPerSecond, clientNode, nodeResults.ServerNode, megabytesPerSecond)
}
} }
}) })
}) })

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@ -21,20 +21,26 @@ import (
"bytes" "bytes"
"encoding/json" "encoding/json"
"fmt" "fmt"
"github.com/pkg/errors"
"math"
"strconv" "strconv"
"strings" "strings"
"k8s.io/kubernetes/test/e2e/framework" "k8s.io/kubernetes/test/e2e/framework"
) )
// IPerfResults is a struct that stores some IPerfResult const (
megabyte = 1024 * 1024
)
// IPerfResults is a struct that stores some IPerfCSVResult
type IPerfResults struct { type IPerfResults struct {
BandwidthMap map[string]int64 BandwidthMap map[string]int64
} }
// IPerfResult struct modelling an iperf record.... // IPerfCSVResult struct modelling an iperf record....
// 20160314154239,172.17.0.3,34152,172.17.0.2,5001,3,0.0-10.0,33843707904,27074774092 // 20160314154239,172.17.0.3,34152,172.17.0.2,5001,3,0.0-10.0,33843707904,27074774092
type IPerfResult struct { type IPerfCSVResult struct {
date string // field 1 in the csv date string // field 1 in the csv
cli string // field 2 in the csv cli string // field 2 in the csv
cliPort int64 // ... cliPort int64 // ...
@ -46,8 +52,12 @@ type IPerfResult struct {
bandwidthBits int64 bandwidthBits int64
} }
func (i *IPerfCSVResult) bandwidthMB() int64 {
return int64(math.Round(float64(i.bandwidthBits) / float64(megabyte) / 8))
}
// Add adds a new result to the Results struct. // Add adds a new result to the Results struct.
func (i *IPerfResults) Add(ipr *IPerfResult) { func (i *IPerfResults) Add(ipr *IPerfCSVResult) {
if i.BandwidthMap == nil { if i.BandwidthMap == nil {
i.BandwidthMap = map[string]int64{} i.BandwidthMap = map[string]int64{}
} }
@ -68,14 +78,17 @@ func (i *IPerfResults) ToTSV() string {
return buffer.String() return buffer.String()
} }
// NewIPerf parses an IPerf CSV output line into an IPerfResult. // NewIPerf parses an IPerf CSV output line into an IPerfCSVResult.
func NewIPerf(csvLine string) *IPerfResult { func NewIPerf(csvLine string) (*IPerfCSVResult, error) {
if len(csvLine) == 0 {
return nil, errors.New("No iperf output received in csv line")
}
csvLine = strings.Trim(csvLine, "\n") csvLine = strings.Trim(csvLine, "\n")
slice := StrSlice(strings.Split(csvLine, ",")) slice := StrSlice(strings.Split(csvLine, ","))
if len(slice) != 9 { if len(slice) != 9 {
framework.Failf("Incorrect fields in the output: %v (%v out of 9)", slice, len(slice)) return nil, errors.Errorf("Incorrect fields in the output: %v (%v out of 9)", slice, len(slice))
} }
i := IPerfResult{} i := IPerfCSVResult{}
i.date = slice.get(0) i.date = slice.get(0)
i.cli = slice.get(1) i.cli = slice.get(1)
i.cliPort = intOrFail("client port", slice.get(2)) i.cliPort = intOrFail("client port", slice.get(2))
@ -85,7 +98,7 @@ func NewIPerf(csvLine string) *IPerfResult {
i.interval = slice.get(6) i.interval = slice.get(6)
i.transferBits = intOrFail("transfer port", slice.get(7)) i.transferBits = intOrFail("transfer port", slice.get(7))
i.bandwidthBits = intOrFail("bandwidth port", slice.get(8)) i.bandwidthBits = intOrFail("bandwidth port", slice.get(8))
return &i return &i, nil
} }
// StrSlice represents a string slice // StrSlice represents a string slice
@ -106,3 +119,53 @@ func intOrFail(debugName string, rawValue string) int64 {
} }
return value return value
} }
// IPerf2EnhancedCSVResults models the results produced by iperf2 when run with the -e (--enhancedreports) flag.
type IPerf2EnhancedCSVResults struct {
Intervals []*IPerfCSVResult
Total *IPerfCSVResult
}
// ParseIPerf2EnhancedResultsFromCSV parses results from iperf2 when given the -e (--enhancedreports)
// and `--reportstyle C` options.
// Example output:
// 20201210141800.884,10.244.2.24,47880,10.96.114.79,6789,3,0.0-1.0,1677852672,13422821376
// 20201210141801.881,10.244.2.24,47880,10.96.114.79,6789,3,1.0-2.0,1980760064,15846080512
// 20201210141802.883,10.244.2.24,47880,10.96.114.79,6789,3,2.0-3.0,1886650368,15093202944
// 20201210141803.882,10.244.2.24,47880,10.96.114.79,6789,3,3.0-4.0,2035417088,16283336704
// 20201210141804.879,10.244.2.24,47880,10.96.114.79,6789,3,4.0-5.0,1922957312,15383658496
// 20201210141805.881,10.244.2.24,47880,10.96.114.79,6789,3,5.0-6.0,2095316992,16762535936
// 20201210141806.882,10.244.2.24,47880,10.96.114.79,6789,3,6.0-7.0,1741291520,13930332160
// 20201210141807.879,10.244.2.24,47880,10.96.114.79,6789,3,7.0-8.0,1862926336,14903410688
// 20201210141808.878,10.244.2.24,47880,10.96.114.79,6789,3,8.0-9.0,1821245440,14569963520
// 20201210141809.849,10.244.2.24,47880,10.96.114.79,6789,3,0.0-10.0,18752208896,15052492511
func ParseIPerf2EnhancedResultsFromCSV(output string) (*IPerf2EnhancedCSVResults, error) {
var parsedResults []*IPerfCSVResult
for _, line := range strings.Split(output, "\n") {
parsed, err := NewIPerf(line)
if err != nil {
return nil, err
}
parsedResults = append(parsedResults, parsed)
}
if parsedResults == nil || len(parsedResults) == 0 {
return nil, errors.New("no results parsed from iperf2 output")
}
// format:
// all but last lines are intervals
intervals := parsedResults[:len(parsedResults)-1]
// last line is an aggregation
total := parsedResults[len(parsedResults)-1]
return &IPerf2EnhancedCSVResults{
Intervals: intervals,
Total: total,
}, nil
}
// IPerf2NodeToNodeCSVResults models the results of running iperf2 between a daemonset of clients and
// a single server. The node name of the server is captured, along with a map of client node name
// to iperf2 results.
type IPerf2NodeToNodeCSVResults struct {
ServerNode string
Results map[string]*IPerf2EnhancedCSVResults
}