ipython: How do I set scrollback history length?

[keflavich]

My readline/scrollback history is limited to a small number. I can't determine what that number is, but it's likely ~100-200ish. I frequently lose important commands that I then have to dig back up.

How can I set the scrollback history length? Also, how can I browse that history using something other than the up arrow?

I have tried adding this:

import readline
readline.set_history_length(999999999)

to one of my ipython startup files, but it has no effect.