Systems and methods are described for smoothing-out latency of IO operations processed by a distributed storage system. In some examples, latency is distributed among IO operations to more evenly spread processing of the IO operations over an IO processing interval. A target latency for IO operations for a volume of a distributed storage system is periodically calculated each sample period based on the number of IO operations to be processed during the next IO processing interval for the volume. As IO operations are received for the volume, a latency may be associated with the IO operation based on the target latency and the IO operation may be queued or synchronously processed as appropriate. Responsive to expiration of a time period that is based on at time at which a given IO operation at the head of the queue was received and the assigned latency, the given IO operation is dequeued and processed.