Time stamping transactions to validate atomic operations in multiprocessor systems

A multi-core microprocessor has a plurality of processor cores which are coupled to a bridge element. The bridge element sends transactions to and/or receives transactions from the processor cores, where each transaction has one or more packets. The transactions include atomic transactions. The bridge element comprises a buffer unit storing a time stamp for each packet sent or received. Furthermore, a multi-core multi-node processor system is provided that has debug hardware to capture and time stamp intra-node and/or inter-node transaction packets. Atomic operations are, for example, atomic read-modify-write instructions.