How to patch ruby for GC tuning and faster requiring

after_use_192-patched.sh

case "$rvm_ruby_string" in
  *ruby-1.9.2*-patched)
    export RUBY_HEAP_MIN_SLOTS=1000000
    export RUBY_HEAP_SLOTS_INCREMENT=1000000
    export RUBY_HEAP_SLOTS_GROWTH_FACTOR=1
    export RUBY_GC_MALLOC_LIMIT=1000000000
    export RUBY_HEAP_FREE_MIN=500000
    export RUBY_FREE_MIN=$RUBY_HEAP_FREE_MIN
    ;;
  *)
    unset RUBY_HEAP_MIN_SLOTS RUBY_HEAP_SLOTS_INCREMENT RUBY_HEAP_SLOTS_GROWTH_FACTOR RUBY_GC_MALLOC_LIMIT RUBY_HEAP_FREE_MIN RUBY_FREE_MIN
    ;;
  esac

# To use this hook for REE, replace line 2 with the following:
# *ree*|*ruby-1.9.2*-patched)

install.sh

curl https://raw.github.com/gist/856296/patch-1.9.2-gc.patch > ~/192-gc.patch
curl https://raw.github.com/gist/1008945/load.patch > ~/192-load.patch
rvm get head
rvm reload

# create ruby called: ruby-1.9.2-p180-patched
rvm install ruby-1.9.2-p180 --patch ~/192-gc.patch --patch ~/192-load.patch -n patched

# create after_use hook to set desired ENV variables
curl https://raw.github.com/gist/1120753/after_use_192-patched.sh > $rvm_path/hooks/after_use_192-patched
chmod u+x $rvm_path/hooks/after_use_192-patched

rm ~/192-gc.patch ~/192-load.patch

curl https://raw.github.com/gist/1120753/install.sh | sh

The way this is written you will have a ruby version ending with "-patched", so you'll have to modify your .rvmrc files to use it. If you want to just patch the "standard" ruby version and not have a version called "xxx-patched": leave the -n patched option off of the rvm install command, and modify the after_use hook appropriately