Who has a longer song Led Zeppelin or Iron Butterfly?

Led Zeppelin's song "In My Time of Dying" from their 1975 album Physical Graffiti has a running time of 11:04 minutes.

Iron Butterfly's song "In-A-Gadda-Da-Vida" from their 1968 album of the same name has a running time of 17:05 minutes.

Therefore, Iron Butterfly has the song with the longer running time.