1. A system, comprising: a cost function evaluator configured to: obtain a cost function; evaluate, for each of a plurality of groups of nodes, the cost function, including by: obtaining, for a given group of nodes, one or more reliability values associated with the given group of nodes, wherein the one or more reliability values include sign and magnitude; and selecting, for the given group of nodes, a reliability value with a smallest magnitude, wherein the evaluated cost function for the given group of nodes is set to the smallest magnitude; select one of the plurality of groups of nodes based at least in part on the evaluated cost functions; and a message updater configured to perform error correction decoding related processing on the selected group of nodes.