[ruby-core:67515] MRI without GIL status

In this video Matz talks about a compile option to disable GIL in MRI 
about 10 minutes:

https://www.youtube.com/watch?v=_zoG2i7pMxg

I'm wondering what is the status for this. I'd like to give it a try and 
measure an specific part of the web application I maintain which I feel 
could benefit from the GIL removal. I feel it could improve a lot the 
total request time for an specific request...

I'd love to get more details about the current status. Is it already 
implemented? Which branch? What is the option name?

Thanks in advance,
Rodrigo.