Increasing server utilization in modern datacenters also increases the likelihood of contention on physical resources and unexpected behavior due to side-effects from interfering applications. Existing resource accounting mechanisms are too coarse-grained for allowing services to track the causes of such variations in their execution. We make the case for measuring resource consumption at system-call level and outline the design of Resourceful, a system that offers applications the ability of querying this data at runtime with low overhead, accounting for costs incurred both synchronously and asynchronously after a given call.