Benchmark of C callbacks in LuaJIT 2.0.0-beta10

luajit_benchmark_callback.lua

local ffi = require"ffi"
jit.on()

ffi.cdef[[
    typedef int (*getval_func)();
    
    /* imagine these are C functions */
    typedef void (*sum_push_func)(int* total, getval_func getval);
    typedef void (*sum_pull_func)(int* total, int val);
]]

local sum_push = ffi.cast("sum_push_func", function(total_ptr, getval_ptr)
    total_ptr[0] = total_ptr[0]+getval_ptr()
end)
local sum_pull = ffi.cast("sum_pull_func", function(total_ptr, val)
    total_ptr[0] = total_ptr[0]+val
end)

local getval = function()
    return 6
end
local getval_ptr = ffi.cast("getval_func", getval)


function test_push(n)
    local total_ptr = ffi.new("int[1]", 0)
    for i = 1, n do
        sum_push(total_ptr, getval_ptr)
    end
    return total_ptr[0]
end

function test_pull(n)
    local total_ptr = ffi.new("int[1]", 0)
    for i = 1, n do
        sum_pull(total_ptr, getval())
    end
    return total_ptr[0]
end

local gettime = os.clock
local fmt = "%-10s %-16s %-16s %-16s %-16s"
local jit_options = {jit.status()} local jit_on = table.remove(jit_options, 1)
print(jit.version.. " ("..jit.os.." "..jit.arch..")")
print("JIT: "..(jit_on and "ON" or "OFF").." "..table.concat(jit_options, " "))
print(fmt:format("n", "Push Time", "Pull Time", "Push Mem", "Pull Mem"))
function math.round(n, p) return math.floor(n*p)/p end
local trials = 3
for i = 8, 24, 4 do
    local n = 2^i
    
    local time_total_push, time_total_pull = 0, 0
    local memu_total_push, memu_total_pull = 0, 0
    local res_push, res_pull
    for i = 1, trials do
        collectgarbage("collect")
        collectgarbage("collect")
        local time_push = os.clock()
        res_push = test_push(n)
        time_push = os.clock()-time_push
        time_total_push = time_total_push+time_push
        memu_total_push = memu_total_push+collectgarbage("count")
        
        collectgarbage("collect")
        collectgarbage("collect")
        local time_pull = os.clock()
        res_pull = test_pull(n)
        time_pull = os.clock()-time_pull
        time_total_pull = time_total_pull+time_pull
        memu_total_pull = memu_total_pull+collectgarbage("count")
    end
    
    print(fmt:format(
        n,
        math.round(time_total_push/trials, 10^6),
        math.round(time_total_pull/trials, 10^6),
        math.round(memu_total_push/trials, 10^6),
        math.round(memu_total_pull/trials, 10^6)
    ))
end

--[[
LuaJIT 2.0.0-beta10 (Windows x64)
JIT: ON CMOV SSE2 SSE3 SSE4.1 fold cse dce fwd dse narrow loop abc sink fuse
n          Push Time        Pull Time        Push Mem         Pull Mem
256        0                0                63.247721        59.346679
4096       0.002666         0.000999         183.346679       119.346679
65536      0.036666         0.015333         2103.346679      1079.346679
1048576    0.620666         0.272            32823.346679     16439.346679
16777216   9.439666         4.227666         524343.346679    262199.346679
]]

LuaJIT 2.1.1710088188 (Windows x64)
JIT: ON SSE3 SSE4.1 fold cse dce fwd dse narrow loop abc sink fuse
n          Push Time        Pull Time        Push Mem         Pull Mem
256        0.000666         0.000333         65.730794        59.944335
4096       0.006            0.002666         113.381835       84.014648
65536      0.058333         0.026            72.881835        73.561523
1048576    0.903333         0.418999         88.631835        104.100585
16777216   14.506666        6.770666         75.131835        89.217773