Re: [Tarantool-patches] [PATCH v1 luajit 13/41] perf: adjust mandelbrot-bit in LuaJIT-benches

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

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Hi, Sergey!

thanks for the patch! See my comments.

Sergey

On 10/24/25 13:50, 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.
>
> The output is redirected to /dev/null. The check is skipped since it is
> very inconvenient to check the binary output, especially since it may be
> configured by the parameter.
> ---
>   perf/LuaJIT-benches/mandelbrot-bit.lua | 86 +++++++++++++++++---------
>   1 file changed, 57 insertions(+), 29 deletions(-)
>
> diff --git a/perf/LuaJIT-benches/mandelbrot-bit.lua b/perf/LuaJIT-benches/mandelbrot-bit.lua
> index 91d96975..a6b5e1f8 100644
> --- a/perf/LuaJIT-benches/mandelbrot-bit.lua
> +++ b/perf/LuaJIT-benches/mandelbrot-bit.lua
> @@ -1,33 +1,61 @@
> -
>   local bit = require("bit")
> -local bor, band = bit.bor, bit.band
> -local shl, shr, rol = bit.lshift, bit.rshift, bit.rol
> -local write, char, unpack = io.write, string.char, unpack
> -local N = tonumber(arg and arg[1]) or 100
> -local M, buf = 2/N, {}
> -write("P4\n", N, " ", N, "\n")
> -for y=0,N-1 do
> -  local Ci, b, p = y*M-1, -16777216, 0
> -  local Ciq = Ci*Ci
> -  for x=0,N-1,2 do
> -    local Cr, Cr2 = x*M-1.5, (x+1)*M-1.5
> -    local Zr, Zi, Zrq, Ziq = Cr, Ci, Cr*Cr, Ciq
> -    local Zr2, Zi2, Zrq2, Ziq2 = Cr2, Ci, Cr2*Cr2, Ciq
> -    b = rol(b, 2)
> -    for i=1,49 do
> -      Zi = Zr*Zi*2 + Ci; Zi2 = Zr2*Zi2*2 + Ci
> -      Zr = Zrq-Ziq + Cr; Zr2 = Zrq2-Ziq2 + Cr2
> -      Ziq = Zi*Zi; Ziq2 = Zi2*Zi2
> -      Zrq = Zr*Zr; Zrq2 = Zr2*Zr2
> -      if band(b, 2) ~= 0 and Zrq+Ziq > 4.0 then b = band(b, -3) end
> -      if band(b, 1) ~= 0 and Zrq2+Ziq2 > 4.0 then b = band(b, -2) end
> -      if band(b, 3) == 0 then break end
> +
> +local bench = require("bench").new(arg)
> +
> +local N = tonumber(arg and arg[1]) or 5000
> +
> +local function payload()
> +  -- These functions must not be an upvalue but the stack slot.
please add here details about performance impact
> +  local N = N
> +  local bor, band = bit.bor, bit.band
> +  local shl, shr, rol = bit.lshift, bit.rshift, bit.rol
> +  local write, char, unpack = io.write, string.char, unpack
> +
> +  local M, buf = 2/N, {}
> +  write("P4\n", N, " ", N, "\n")
> +  for y=0,N-1 do
please add spaces here and below
> +    local Ci, b, p = y*M-1, -16777216, 0
> +    local Ciq = Ci*Ci
> +    for x=0,N-1,2 do
> +      local Cr, Cr2 = x*M-1.5, (x+1)*M-1.5
> +      local Zr, Zi, Zrq, Ziq = Cr, Ci, Cr*Cr, Ciq
> +      local Zr2, Zi2, Zrq2, Ziq2 = Cr2, Ci, Cr2*Cr2, Ciq
> +      b = rol(b, 2)
> +      for i=1,49 do
> +        Zi = Zr*Zi*2 + Ci; Zi2 = Zr2*Zi2*2 + Ci
> +        Zr = Zrq-Ziq + Cr; Zr2 = Zrq2-Ziq2 + Cr2
> +        Ziq = Zi*Zi; Ziq2 = Zi2*Zi2
> +        Zrq = Zr*Zr; Zrq2 = Zr2*Zr2
> +        if band(b, 2) ~= 0 and Zrq+Ziq > 4.0 then b = band(b, -3) end
> +        if band(b, 1) ~= 0 and Zrq2+Ziq2 > 4.0 then b = band(b, -2) end
> +        if band(b, 3) == 0 then break end
> +      end
> +      if b >= 0 then p = p + 1; buf[p] = b; b = -16777216; end
>       end
> -    if b >= 0 then p = p + 1; buf[p] = b; b = -16777216; end
> -  end
> -  if b ~= -16777216 then
> -    if band(N, 1) ~= 0 then b = shr(b, 1) end
> -    p = p + 1; buf[p] = shl(b, 8-band(N, 7))
> +    if b ~= -16777216 then
> +      if band(N, 1) ~= 0 then b = shr(b, 1) end
> +      p = p + 1; buf[p] = shl(b, 8-band(N, 7))
> +    end
> +    write(char(unpack(buf, 1, p)))
>     end
> -  write(char(unpack(buf, 1, p)))
>   end
> +
> +local stdout = io.output()
> +
> +bench:add({
> +  name = "mandelbrot_bit",
> +  items = N,
> +  -- XXX: This is inconvenient to have the binary file in the
> +  -- repository for the comparison. If the check is needed, run
> +  -- the payload manually.
> +  skip_check = true,
> +  setup = function()
> +    io.output("/dev/null")
> +  end,
> +  teardown = function()
> +    io.output(stdout)
> +  end,
> +  payload = payload,
> +})
> +
> +bench:run_and_report()
>

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