Nearly a month after Samsung started rolling out the Marshmallow update to the Galaxy S5, the most widely available model (SM-G900F) of the South Korean company's 2014 flagship has begun receiving the update. Currently, the update - which brings Marshmallow version 6.0.1 - is hitting units in SriLanka, with European and other SM-G900Fs likely to get it soon. Given that the roll-out has just begun, it may take some time for the update to hit your Galaxy S5. However, if you're feeling impatient, you can manually check for it by heading to the Settings menu on your device. Via
Source: http://www.gsmarena.com/marshmallow_for_samsung_galaxy_s5_to_be_more_widely_available_as_model_smg900f_starts_getting_it-news-17835.php