RAN virtualization will become a key technology for the last mileof next-generation mobile networks driven by initiatives such asthe O-RAN alliance. However, due to the computing fluctuationsinherent to wireless dynamics and resource contention in sharedcomputing infrastructure, the price to migrate fromdedicatedtosharedplatforms may be too high. Indeed, we show in this paperthat the baseline architecture of a base station’s distributed unit(DU) collapses upon moments of deficit in computing capacity.Recent solutions to accelerate some signal processing tasks certainlyhelp but do not tackle the core problem: a DU pipeline that requirespredictable computing to provide carrier-grade reliability.We present Nuberu, a novel pipeline architecture for 4G/5G DUsspecifically engineered for non-deterministic computing platforms.Our design has one key objective to attain reliability: to guaranteea minimum set of signals that preserve synchronization betweenthe DU and its users during computing capacity shortages and,provided this, maximize network throughput. To this end, we usetechniques such as tight deadline control, jitter-absorbing buffers,predictive HARQ, and congestion control. Using an experimentalprototype, we show that Nuberu attains>95%of the theoreticalspectrum efficiency in hostile environments, where state-of-artapproaches lose connectivity, and at least 80% resource savings.