Vagrant setting - Use all CPU cores and 1/4 system memory

Vagrant.Multi.CPU.rb

# http://www.stefanwrobel.com/how-to-make-vagrant-performance-not-suck

config.vm.provider "virtualbox" do |v|
  host = RbConfig::CONFIG['host_os']

  # Give VM 1/4 system memory & access to all cpu cores on the host
  if host =~ /darwin/
    cpus = `sysctl -n hw.ncpu`.to_i
    # sysctl returns Bytes and we need to convert to MB
    mem = `sysctl -n hw.memsize`.to_i / 1024 / 1024 / 4
  elsif host =~ /linux/
    cpus = `nproc`.to_i
    # meminfo shows KB and we need to convert to MB
    mem = `grep 'MemTotal' /proc/meminfo | sed -e 's/MemTotal://' -e 's/ kB//'`.to_i / 1024 / 4
  else # sorry Windows folks, I can't help you
    cpus = 2
    mem = 1024
  end

  v.customize ["modifyvm", :id, "--memory", mem]
  v.customize ["modifyvm", :id, "--cpus", cpus]
end

#Following snippet helped me give all cores to the guest os from a windows machine.

config.vm.provider "virtualbox" do |vb|
    host = RbConfig::CONFIG['host_os']

    if host =~ /darwin/
      cpus = `sysctl -n hw.ncpu`.to_i
    elsif host =~ /linux/
      cpus = `nproc`.to_i
    #Works in windows like a charm
    elsif host =~ /cygwin|mswin|mingw|bccwin|wince|emx/
      cpus = `wmic cpu get NumberOfCores /VALUE`.split("=")[1].to_i
    else
      cpus = 1
    end

    # Customize the amount of memory on the VM:
    vb.memory = "1024"
    vb.cpus    = cpus
  end