helpers to consume CPU for specific amount of time

bench.lua

local clock = require 'clock'.time

function getms1()
	local bench = function(f, ...)
		local tail = function(s, ...)
			return clock()-s, ...
		end
		local s = clock()
		return tail(s, f(...))
	end

	local function loop(n) local x = 0 for i = 1, n do x = x + 1 end end

	-- initial value:
	local x = 100*1000
	local ms1 = 0.001
	for i = 1, 100 do
		local lat = bench(loop, x)
		x = x*ms1/lat
	end

	local ms10 = 10*ms1
	for i = 1, 10 do
		local lat_10 = bench(loop, 10*x)
		x = x*ms10/lat_10
	end

	return function() return loop(x) end, x
end

longfunc = function(st)
	local time = clock.time
	local s = time()
	local c = st*1000
	local x = c
	local now

	repeat
		for i = 1, c do
			ms1()
		end
		now = time()
		c = 1000*(s+st-now)
	until (s+st) < now
	return now - s, x
end