1. A method of collective operation management in a parallel computer, the parallel computer including a first compute node operatively coupled for data communications over a tree data communications network with a plurality of child compute nodes, the method comprising: performing, by the child compute nodes, a first collective operation; for each of the child compute nodes: receiving from a child compute node, by the first compute node, a result of the first collective operation performed by the child compute node; for each result received from the child compute node, storing, by the first compute node, a timestamp indicating a time that the child compute node completed the first collective operation; and managing based on the stored timestamps, by the first compute node, execution of a second collective operation over the tree data communications network, including: identifying an order in which the child compute nodes completed the first collective operation including identifying a second set of child compute nodes that completed the first collective operation after a first set of child compute nodes; allocating additional resources to the second set of child compute nodes based at least in part on the identified order of completion of the first collective operation, wherein the first set of child compute nodes includes more than one compute node and the second set of child compute nodes includes more than one compute node; generating, based on the stored timestamps, an evaluation of the first collective operation; and based on the evaluation: splitting the tree data communications network into at least two different networks; and selecting from a plurality of collective operation algorithms at least two different algorithms for the at least two different networks.