A method, computer program product, and system identify a low-cost time to re-boot a system. The method includes a processor obtaining a request for a re-boot of a system. The processor obtains identifiers of uncompleted tasks executing in the system. Based on obtaining the identifiers, the processor obtains a task cost of each task of the uncompleted tasks, where a value of the task cost of each task relates to a portion of each task completed by the processor at a given time. The processor determines, based on the task costs associated with the uncompleted tasks, a re-boot cost for re-booting the system at the given time. The processor determined a system cost for not re-booting the system at the given time. The processor compares the re-boot cost to the system cost to determine whether to re-boot the system at the given time in response to the request.