Many functions of operating systems are keen to be realised as feedback controllers. Doing so has a non negligible design impact, but also a significant payoff in terms of simplicity and generality. This paper presents a complete operating system scheduler, at present implemented in a microcontroller kernel, entirely composed of a PI-based control structure. The proposed scheduler is experimented with in several load conditions. In all of them, it performs in a comparable manner with respect to the classical (i.e., not control-based) policy optimised for that condition, as long as design assumptions such as schedulability are met. In addition, if some off-design situation is encountered, the proposed control-based scheduler definitely outperforms those not conceived as controllers.