emacs windows, distribute the width through the frame

I used once a very nice emacs function that set all my windows (emacs windows, not frames) width evenly.

If you open emacs and do C-x 3 twice in a row, you get three vertical windows. Then running the function I am looking for makes the width of these windows the same.

I can't for the life of me find this function again. Wouldn't someone help me 开发者_开发问答to:

• find the name of the function
• give me the keyboard shortcut if any
• tell me what I should have done to find the answer by myself

Thanks!

You're looking for M-x balance-windows.