A MoonGen script that attemps to achieve the highest throughput supported by DUT while minimizing packet losses.

minimize-pkt-losses.lua

local mg     = require "moongen"
local lm     = require "libmoon"
local memory = require "memory"
local device = require "device"
local stats  = require "stats"
local limiter = require "software-ratecontrol"
local pcap    = require "pcap"

function configure(parser)
	parser:description("Attemps to achieve the highest throughput supported by DUT while minimizing packet losses.")
	parser:argument("dev", "Device to transmit/receive from."):convert(tonumber)
	parser:option("-r --rate", "Transmit rate in Mbit/s."):default(0.2):convert(tonumber)
	parser:option("-f --file", "Filename of pcap.")
	parser:option("-c --cores", "Nb of cores"):default(1):convert(tonumber)
end

function master(args)
	local dev = device.config({port = args.dev, rxQueues = args.cores, txQueues = args.cores})
	device.waitForLinks()
	for i = 0, args.cores - 1, 1 do
		local queue = dev:getTxQueue(i)
		local rateLimiter = limiter:new(queue, "custom", 1 / args.rate * 1000)
		if args.file then
			mg.startTask("pcapSlave", queue, args.rate, rateLimiter, dev, i == 0, args.file)
		else
			mg.startTask("loadSlave", queue, args.rate, rateLimiter, dev, i == 0)
		end
	end
	mg.startTask("counterSlave", dev:getRxQueue(0))
	mg.waitForTasks()
end

function pcapSlave(queue, rate, rateLimiter, dev, displayStats, file)
	local pcapFile = pcap:newReader(file)
	local mem = memory.createMemPool()
	local bufs = mem:bufArray(128)
	local linkSpeed = dev:getLinkStatus().speed
	local txCtr = stats:newDevTxCounter(dev, "plain")
	local rxCtr = stats:newDevRxCounter(dev, "plain")
	local lastTs = 0
	while mg.running() do
		local n = pcapFile:read(bufs)
		if n == 0 then
			pcapFile:reset()
		else
			for i = 1, n  do
				local buf = bufs[i]
				buf:setDelay(rate * linkSpeed / 8)
			end
			rateLimiter:sendN(bufs, n)
			
			if displayStats then
				txCtr:update()
				rxCtr:update()
			end
			tx = txCtr.mpps[#txCtr.mpps]
			rx = rxCtr.mpps[#rxCtr.mpps]
			-- Wait 2s for throughput to stabilize before changing rate again.
			local ts = lm.getTime()
			if tx and rx and ts >= lastTs + 2 then
				lastTs = ts
				local factor = 0.002
				-- We're far from target throughput, let's speed things up!
				if tx - rx > 0.5 then
					factor = 0.03
				end
				if tx > rx + 0.05 then
					rate = rate + factor
				else
					rate = rate - factor
				end
			end
		end
	end
	print(rate)
	print(tx)
	print(rx)
	if displayStats then
		txCtr:finalize()
		rxCtr:finalize()
	end
end

function loadSlave(queue, rate, rateLimiter, dev, displayStats)
	local mem = memory.createMemPool(function(buf)
		buf:getUdpPacket():fill{
			ethSrc = txDev,
			ethDst = "00:15:4d:13:15:2b",
			ip4Src = "192.168.1.3",
			ip4Dst = "192.168.1.2",
			udpSrc = 2000,
			udpDst = 3000,
			pktLength = 60
		}
	end)
	local linkSpeed = dev:getLinkStatus().speed
	local bufs = mem:bufArray(128)
	local txCtr = stats:newDevTxCounter(dev, "plain")
	local rxCtr = stats:newDevRxCounter(dev, "plain")
	local lastTs = 0
	while mg.running() do
		bufs:alloc(60)
		for _, buf in ipairs(bufs) do
			buf:setDelay(rate * linkSpeed / 8)
		end
		bufs:offloadUdpChecksums()
		rateLimiter:send(bufs)
		
		if displayStats then
			txCtr:update()
			rxCtr:update()
		end
		tx = txCtr.mpps[#txCtr.mpps]
		rx = rxCtr.mpps[#rxCtr.mpps]
		-- Wait 2s for throughput to stabilize before changing rate again.
		local ts = lm.getTime()
		if tx and rx and ts >= lastTs + 2 then
			lastTs = ts
			local factor = 0.002
			-- We're far from target throughput, let's speed things up!
			if tx - rx > 0.5 then
				factor = 0.03
			end
			if tx > rx + 0.05 then
				rate = rate + factor
			else
				rate = rate - factor
			end
		end
	end
	print(rate)
	print(tx)
	print(rx)
	if displayStats then
		txCtr:finalize()
		rxCtr:finalize()
	end
end

function counterSlave(queue)
	local bufs = memory.bufArray()
	while mg.running() do
		local rx = queue:tryRecv(bufs, 100)
		bufs:free(rx)
	end
end