Re: [Tarantool-patches] [PATCH v2 luajit 09/41] perf: adjust fannkuch in LuaJIT-benches

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

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Hi, Sergey!

thanks for the patch! LGTM

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/fannkuch.lua | 44 +++++++++++++++++++++++++++++---
>   1 file changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/perf/LuaJIT-benches/fannkuch.lua b/perf/LuaJIT-benches/fannkuch.lua
> index 2a4cd426..f51e0eaf 100644
> --- a/perf/LuaJIT-benches/fannkuch.lua
> +++ b/perf/LuaJIT-benches/fannkuch.lua
> @@ -1,3 +1,11 @@
> +-- The benchmark that checks the performance of operations on
> +-- small integers and vectors of integers and the performance of
> +-- inner loops of the benchmark. The benchmark finds the maximum
> +-- number of flips in the table needed for any permutation.
> +-- For the details see:
> +--https://benchmarksgame-team.pages.debian.net/benchmarksgame/description/fannkuchredux.html
> +
> +local bench = require("bench").new(arg)
>   
>   local function fannkuch(n)
>     local p, q, s, odd, check, maxflips = {}, {}, {}, true, 0, 0
> @@ -6,7 +14,6 @@ local function fannkuch(n)
>       -- Print max. 30 permutations.
>       if check < 30 then
>         if not p[n] then return maxflips end	-- Catch n = 0, 1, 2.
> -      io.write(unpack(p)); io.write("\n")
>         check = check + 1
>       end
>       -- Copy and flip.
> @@ -46,5 +53,36 @@ local function fannkuch(n)
>     until false
>   end
>   
> -local n = tonumber(arg and arg[1]) or 1
> -io.write("Pfannkuchen(", n, ") = ", fannkuch(n), "\n")
> +local n = tonumber(arg and arg[1]) or 11
> +
> +-- Precomputed numbers taken from "Performing Lisp Analysis of the
> +-- FANNKUCH Benchmark":
> +--https://dl.acm.org/doi/pdf/10.1145/382109.382124
> +local FANNKUCH = { 0, 1, 2, 4, 7, 10, 16, 22, 30, 38, 51, 65, 80 }
> +
> +local function factorial(n)
> +  local fact = 1
> +  for i = 2, n do
> +    fact = fact * i
> +  end
> +  return fact
> +end
> +
> +bench:add({
> +  name = "fannkuch",
> +  payload = function()
> +    return fannkuch(n)
> +  end,
> +  checker = function(res)
> +    if n > #FANNKUCH then
> +      -- Not precomputed, so can't check.
> +      return true
> +    else
> +      return res == FANNKUCH[n]
> +    end
> +  end,
> +  -- Assume that we count permutations here.
> +  items = factorial(n),
> +})
> +
> +bench:run_and_report()

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