In this workshop the attendees will have the opportunity to delve into the topic of application auto-tuning, presented by developers and performance engineers from the AutoTune project. This workshop will present the theory behind auto-tuning, focusing on the conceptual basis and discussing the latest advancements in the field within the AutoTune project, whereas the related tutorial in the afternoon (Code Auto-Tuning with the Periscope Tuning Framework) will provide a practical perspective to auto-tuning, exemplifying with use cases how to best harness and tailor performance analysers to tune real applications.