A multiprocessor data processing system includes a plurality of processors
coupled to an interconnect and to a global promotion facility containing
at least one promotion bit field. A first processor executes a high speed
instruction sequence including a load-type instruction to acquire a
promotion bit field within the global promotion facility exclusive of at
least a second processor. The request may be made visible to all
processors coupled to the interconnect. In response to execution of the
load-type instruction, a register of the first processor receives a
register bit field indicating whether or not the promotion bit field was
acquired by execution of the load-type instruction. While the first
processor holds the promotion bit field exclusive of the second
processor, the second processor is permitted to initiate a request on the
interconnect. Advantageously, promotion bit fields are handled separately
from data, and the communication of promotion bit fields does not entail
the movement of data cache lines.