Hi Res Timer

wiki

This is used by BenchmarkModule, my benchmarking toolkit.

HiResTimer.lua

---------------------------

-- this module provide a function

-- HiResTimer.clock() which returns a high resolution timer

---------------------------

module("HiResTimer",package.seeall)



--

-- take the alien module

--

local alien=require"alien"



--

-- get the kernel dll

--

local kernel32=alien.load("kernel32.dll")



--

-- get dll functions

--

local QueryPerformanceCounter=kernel32.QueryPerformanceCounter

QueryPerformanceCounter:types{ret="int",abi="stdcall","pointer"}

local QueryPerformanceFrequency=kernel32.QueryPerformanceFrequency

QueryPerformanceFrequency:types{ret="int",abi="stdcall","pointer"}



--------------------------------------------

--- utility : convert a long to an unsigned long value

-- (because alien does not support longlong nor ulong)

--------------------------------------------

local function lu(long)

	return long<0 and long+0x80000000+0x80000000 or long

end



--------------------------------------------

--- Query the performance frequency.

-- @return (number)

--------------------------------------------

local function qpf()

	local frequency=alien.array('long',2)

	QueryPerformanceFrequency(frequency.buffer)

	return  math.ldexp(lu(frequency[1]),0)

		    +math.ldexp(lu(frequency[2]),32)

end



--------------------------------------------

--- Query the performance counter.

-- @return (number)

--------------------------------------------

local function qpc()

	local counter=alien.array('long',2)

	QueryPerformanceCounter(counter.buffer)

	return	 math.ldexp(lu(counter[1]),0)

			+math.ldexp(lu(counter[2]),32)

end



--------------------------------------------

-- get the startup values

--------------------------------------------

local f0=qpf()

local c0=qpc()



--------------------------------------------

--- Return a hires clock

-- @return (number) elapsed seconds since load of the module

--------------------------------------------

function clock()

	local c1=qpc()

	return (c1-c0)/f0

end



return HiResTimer

Example, how to use

local hrt=require"HiResTimer"



local t0=hrt.clock()



for i=1,1000*1000 do

	local j=i*i

end



local t1=hrt.clock()



print("Took",t1-t0,"seconds")

Linux??

HiResTimer v.s. socket.gettime()

I've been using LuaSocket?'s gettime function as a generic high-resolution timer. It seems to work reasonably well on Windows, Linux, and BSD. Also, LuaSocket? is usually already present. -ScottVokes?

For me socket.gettime() is not hires enough. Check this one

local hrt=require"HiResTimer"

local socket=require"socket"

local function printf(...)

    io.write(string.format(...))

end

for loops=0,100000,1000 do

    printf("%6d loops ",loops)

    local t0=hrt.clock()

    for i=1,loops do local j=math.sin(123) end

    local t1=hrt.clock()

    printf("hrt=%9.3f ms",(t1-t0)*1000)

    local t0=socket.gettime()

    for i=1,loops do local j=math.sin(123) end

    local t1=socket.gettime()

    printf(" socket=%9.3f ms\n",(t1-t0)*1000)

    --if t1>t0 then  break end

end

     0 loops hrt=    0.035 ms socket=    0.000 ms

  1000 loops hrt=    0.327 ms socket=    0.000 ms

  2000 loops hrt=    0.461 ms socket=    0.000 ms

  3000 loops hrt=    0.685 ms socket=    0.000 ms

  4000 loops hrt=    0.905 ms socket=    0.000 ms

  5000 loops hrt=    1.123 ms socket=    0.000 ms

  6000 loops hrt=    1.391 ms socket=    0.000 ms

  7000 loops hrt=    1.565 ms socket=    0.000 ms

  8000 loops hrt=    1.801 ms socket=   15.625 ms

  9000 loops hrt=    2.032 ms socket=    0.000 ms

 10000 loops hrt=    2.244 ms socket=    0.000 ms

:::

 90000 loops hrt=   22.061 ms socket=   15.625 ms

 91000 loops hrt=   20.248 ms socket=   31.250 ms

 92000 loops hrt=   22.713 ms socket=   15.625 ms

 93000 loops hrt=   22.575 ms socket=   15.625 ms

 94000 loops hrt=   21.200 ms socket=   15.625 ms

 95000 loops hrt=   22.974 ms socket=   15.625 ms

 96000 loops hrt=   21.370 ms socket=   31.250 ms

 97000 loops hrt=   23.359 ms socket=   31.250 ms

 98000 loops hrt=   21.953 ms socket=   15.625 ms

 99000 loops hrt=   22.304 ms socket=   15.625 ms

100000 loops hrt=   22.887 ms socket=   15.625 ms

(at least on windows) socket.gettime has a resolution of 64 ticks/second, the performancecounter used in hires is above 1000000 ticks/second (exact value may vary with the machine)

for the sake of completeness I've checked socket.gettime on a linux machine

local socket=require"socket"

local function printf(...)

	io.write(string.format(...))

end

for loops=0,100000,1000 do

	printf("%6d loops ",loops)

	local t0=socket.gettime()

	for i=1,loops do local j=math.sin(123) end

	local t1=socket.gettime()

	printf(" socket=%9.3f ms\n",(t1-t0)*1000)

end

     0 loops  socket=    0.002 ms

  1000 loops  socket=    0.509 ms

  2000 loops  socket=    1.017 ms

  3000 loops  socket=    1.485 ms

  4000 loops  socket=    1.172 ms

  5000 loops  socket=    1.477 ms

  6000 loops  socket=    1.776 ms

  7000 loops  socket=    2.078 ms

  8000 loops  socket=    2.381 ms

  9000 loops  socket=    2.850 ms

 10000 loops  socket=    3.000 ms

::::

 90000 loops  socket=   25.086 ms

 91000 loops  socket=   25.474 ms

 92000 loops  socket=   25.696 ms

 93000 loops  socket=   25.991 ms

 94000 loops  socket=   26.368 ms

 95000 loops  socket=   26.634 ms

 96000 loops  socket=   26.922 ms

 97000 loops  socket=   27.096 ms

 98000 loops  socket=   27.463 ms

 99000 loops  socket=   27.776 ms

100000 loops  socket=   27.973 ms

- JoergenVonBargen

The above socket.gettime() code works well on Mac OS X (tested on 10.6.5) as well

Result

     0 loops  socket=    0.001 ms

  1000 loops  socket=    0.156 ms

  2000 loops  socket=    0.264 ms

  3000 loops  socket=    0.399 ms

  4000 loops  socket=    0.529 ms

  5000 loops  socket=    0.667 ms

...

 96000 loops  socket=   12.948 ms

 97000 loops  socket=   12.678 ms

 98000 loops  socket=   12.718 ms

 99000 loops  socket=   12.963 ms

100000 loops  socket=   12.949 ms

-- DougCurrie

See Also

• [Lua/APR time_now] provides sub-microsecond time measurement as well.