The "subject" of the gerund

The doer of the action expressed by the gerund can be:

• the subject of the sentence:
  

  I like getting up early in summer.
  He apologised for not writing for so long.
  I am looking forward to hearing from you.
  My mom insisted on tidying my room.
  Would you mind opening the window?
  

• the noun/pronoun or possessive preceding the gerund:
  

  Irina doesn't like people telling her what to do.
  Sally's constant arguing is getting on my nerves.
  I objected to him/his calling me a liar.
  My mom insisted on me/my tidying my room.
  Would you mind me/my opening the window?

  (The possessive is more formal, and it is less common in everyday conversation.)

• an indefinite or generalised subject (you, one, we, people etc.):
  

  In those days, being a student meant spending long hours in the library.

• unexpressed and understood only from the context:
  

  Going home seemed to be the best idea.