Want to get started with YJIT? See the latest README for details. The short version goes:

    # If you have a YJIT-capable Ruby installed, run with the --yjit flag
    ruby --yjit my_file_to_make_faster.rb
    RUBYOPT="--yjit" rails server

    # Any Ruby 3.1.0 or later has YJIT support
    rvm install ruby-3.1
    ruby-build 3.1.0 ~/.rubies/ruby-3.1.0

YJIT Resources

You can install Ruby 3.1.0 or higher to get the most recent release of YJIT. 3.2.0 or higher is strongly preferred for long-running servers.

Snippets to disassemble chunks of Ruby code:

    # To disassemble Ruby bytecode:
    puts RubyVM::InstructionSequence.disassemble(method :whatever_method)

    # Ruby bytecode plus YJIT assembly language (only on dev YJIT):
    puts RubyVM::YJIT.disasm(method :whatever_method)

    # If you want to do YJIT disassembly, you'll need to run with YJIT
    ruby --yjit my_disassembly_test.rb

    # And when you build Ruby, you'll need to turn on dev YJIT:
    ./configure --yjit-enable=dev

You can find more BBV and YJIT talks and papers in the CRuby YJIT README.

Slides from my talk