Methods, systems and computer program products for monitoring delivered packages are provided. Aspects include receiving, by a co-processor, a data stream and performing processing on the data stream. Aspects also include writing, by the co-processor, a data record into the output buffer. Based on a determination that the data record should replace a most recently stored data record in a cache, aspects include providing, by the co-processor to the cache controller, an instruction for the cache controller to write the data record to a location in the cache obtained from a most recently used address register. Based on a determination that the data record should not replace the most recently stored data record in the cache, aspects include writing, by the cache controller, the data record to an available location in the cache.