You can run this like so:
make requests=100000 concurrency=1000
NOTE: you must have ab & gnuplot installed and GNU make as well. Use homebrew to get these commands
if needed. Must be GNU version of make in order to use the "shell" command in Makefile.
All of these things can be installed via homebrew, but make should already be installed.
brew install gnuplot
brew install homebrew/apache/ab