It is a challenging problem to provide QoS (quality of service) in the virtualization-based cloud computing environment. Existing efforts have addressed this challenge based on either Cost-Oblivious approaches, or Cost-Aware approaches. However, both approaches may suffer frequent QoS violations under typical flash crowd workload. For instance, both approaches ignore the benefit gained after configuration changes. In this paper, a benefit-aware approach according to the profit rate maximization principle is introduced to address this problem. Here, the benefit means the satisfaction percept of the duration that application continuously guarantees the QoS in the new configuration. Experimental results based on TPC-W benchmark show that this benefit-aware approach can save the costs of VM resources as much as 25% and can effectively reduce the QoS violations compared through a cost-aware approach.