Gateway Performance App

That won't really help you much.  Instead, create a streaming hybrid dataset like this 

and then on each cluster member have a Powershell script run every five minutes, pushing data in.

#capture stats
$date = (Get-Date).ToUniversalTime().ToString('yyyy-MM-ddTHH:mm:00.000Z')
$mem = (Get-Counter '\Memory\Available MBytes').CounterSamples.CookedValue
$proc = (Get-Counter '\Processor(_Total)\% Processor Time').CounterSamples.CookedValue
$disk = (Get-Counter '\LogicalDisk(C:)\% free space').CounterSamples.CookedValue
$mashups = 0+(get-process "Microsoft.Mashup.Container.NetFX45" -ErrorAction SilentlyContinue | Measure-Object ).Count
$mashmem = 0+(get-process "Microsoft.Mashup.Container.NetFX45" -ErrorAction SilentlyContinue | Measure-Object WS -Sum ).Sum
$gwmem = 0+(get-process "Microsoft.PowerBI.EnterpriseGateway" | Measure-Object WS -Sum ).Sum
$date1 = (Get-Date)
$proxy = (tnc <your proxy> -Port <your port>).TcpTestSucceeded
$date2 = (Get-Date)
#enforce TLS1.2
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
$payload = @{
"Host" = $env:computername
"Timestamp" = $date
"Available Memory in MB" = $mem
"Processor Load %" = $proc
"% Free on C:" = $disk
"Mashups" = $mashups
"Mashup Memory" = $mashmem
"Gateway Memory" = $gwmem
"Proxy ok" = ($date2 - $date1).TotalSeconds  #$proxy+0
}
#push URL
$endpoint = "https://api.powerbi.com/beta/<your tenant>/datasets/<your dataset>/rows?key=<your push key>"
Invoke-RestMethod -Method Post -Uri "$endpoint" -Body (ConvertTo-Json @($payload))