copyFile with bufferSize instead of hardcoded value

[juancarlospaco]

• copyFile allows to specify bufferSize instead of hardcoded wrong value. Tiny diff.

Performance

• 1200% Performance improvement.

Check it yourself

Execute:

for i in $(seq 0 10); do
  bs=$((1024*2**$i))
  printf "%7s Kb\t" $bs
  timeout --foreground -sINT 2 dd bs=$bs if=/dev/zero of=/dev/null 2>&1 | sed -n 's/.* \([0-9.,]* [GM]B\/s\)/\1/p'
done

Stats

• Hardcoded 8192 or 8000 Kb bufferSize gives 5 GB/s.
• Setting 262144 Kb bufferSize gives 65 GB/s (script suggestion).

[Araq]

No, not a new overload, just add a parameter with a default value.

[github-actions]

Thanks for your hard work on this PR!
The lines below are statistics of the Nim compiler built from a38e3dc

Hint: mm: orc; opt: speed; options: -d:release
170093 lines; 10.322s; 620.043MiB peakmem