Re: [Tarantool-patches] [PATCH v2 luajit 08/41] perf: adjust euler14-bit in LuaJIT-benches

[Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

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Hi, Sergey!

thanks for the patch! Generally LGTM, but the test failed on my machine 
with:

$ ./build/src/luajit perf/LuaJIT-benches/euler14-bit.lua
./build/src/luajit: not enough memory

Sergey

On 12/26/25 12:17, Sergey Kaplun wrote:
> This patch adjusts the aforementioned test to use the benchmark
> framework introduced before. The default arguments are adjusted
> according to the <PARAM_x86.txt> file. The arguments to the script still
> can be provided in the command line run.
> ---
>   perf/LuaJIT-benches/euler14-bit.lua | 65 ++++++++++++++++++++++-------
>   1 file changed, 49 insertions(+), 16 deletions(-)
>
> diff --git a/perf/LuaJIT-benches/euler14-bit.lua b/perf/LuaJIT-benches/euler14-bit.lua
> index 537f2bf3..c4ae3713 100644
> --- a/perf/LuaJIT-benches/euler14-bit.lua
> +++ b/perf/LuaJIT-benches/euler14-bit.lua
> @@ -1,22 +1,55 @@
> +-- The benchmark to check the performance of bitwise operations.
> +-- It finds the longest Collatz sequence using bitwise arithmetic.
> +-- For the details see:
> +--https://projecteuler.net/problem=14
> +
> +local bench = require("bench").new(arg)
>   
>   local bit = require("bit")
>   local bnot, bor, band = bit.bnot, bit.bor, bit.band
>   local shl, shr = bit.lshift, bit.rshift
>   
> -local N = tonumber(arg and arg[1]) or 10000000
> -local cache, m, n = { 1 }, 1, 1
> -if arg and arg[2] then cache = nil end
> -for i=2,N do
> -  local j = i
> -  for len=1,1000000000 do
> -    j = bor(band(shr(j,1), band(j,1)-1), band(shl(j,1)+j+1, bnot(band(j,1)-1)))
> -    if cache then
> -      local x = cache[j]; if x then j = x+len; break end
> -    elseif j == 1 then
> -      j = len+1; break
> +local DEFAULT_N = 2e7
> +local N = tonumber(arg and arg[1]) or DEFAULT_N
> +local drop_cache = arg and arg[2]
> +
> +bench:add({
> +  name = "euler14_bit",
> +  payload = function()
> +    local cache, m, n = { 1 }, 1, 1
> +    if drop_cache then cache = nil end
> +    for i = 2, N do
> +      local j = i
> +      for len = 1, 1000000000 do
> +        j = bor(
> +          band(shr(j, 1), band(j, 1) - 1),
> +          band(shl(j, 1) + j + 1, bnot(band(j, 1) - 1))
> +        )
> +        if cache then
> +          local x = cache[j]
> +          if x then
> +            j = x + len
> +            break
> +          end
> +        elseif j == 1 then
> +          j = len + 1
> +          break
> +        end
> +      end
> +      if cache then cache[i] = j end
> +      if j > m then m, n = j, i end
>       end
> -  end
> -  if cache then cache[i] = j end
> -  if j > m then m, n = j, i end
> -end
> -io.write("Found ", n, " (chain length: ", m, ")\n")
> +    return {n = n, m = m}
> +  end,
> +  checker = function(res)
> +    if N ~= DEFAULT_N then
> +      -- Test only for the default.
> +      return true
> +    else
> +      return res.n == 18064027 and res.m == 623
> +    end
> +  end,
> +  items = N,
> +})
> +
> +bench:run_and_report()

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