Projectile is one of my favourite Emacs packages and I recommend it for everyone coding in Emacs . It sets up many things for you that you'll appreciate whatever language you're programming in.
M-x projectile-regenerate-tags gave me this errors:
projectile-regenerate-tags: ctags: invalid option -- 'e' Try `ctags --help' for a complete list of options.
# apt-get install exuberant-ctags
projectile-regenerate-tags and consequently
pop-tag-mark) worked like a charm.