I refereed to rent controls in the sense that the american OP said are causing price increases in SF (afaik this is simply limiting rent increases for existing contracts, which is the default in Germany).

All of Germany is under rent control in that context, and IMO it works compared to exploding rents in the US and other countries (UK, Israel, most places really aside from some of continental Europe).

    That's because most contracts specify that 
    increasing the rent follows the standard 
    procedure: Over three years, rent can rise 
    by up to 20% (15% in Berlin), if the comparable 
    rents in the area have risen as well (which is
    influenced by market rate). Ultimately, this 
    limits the pace at which rents rise, but not 
    the extent.

This is a form of rent control almost nobody in the rest of the world outside of continental europe enjoys - prices generally rise as quick for current tenants as they do for everyone there: your landlord can tell you tomorrow than the next time your contract is up to renewal (usually yearly), the price will be 2x the current one and if you don't like that you have to leave.