1. A method of managing contexts that execute on a computer system, said method comprising: measuring a skew metric for each coscheduled context in a plurality of coscheduled contexts; determining that the skew metric for at least one of said plurality of coscheduled contexts exceeds a first threshold; in response to said determining, descheduling each of said plurality of coscheduled contexts not already descheduled; and after said descheduling, scheduling a subset of said plurality of coscheduled contexts, wherein said subset comprises less than all of said plurality of coscheduled contexts, and said subset comprises coscheduled contexts having a skew metric that exceeds a second threshold that is not greater than said first threshold.