The Unabridged Pentium 4 IA32 Processor Genealogy

The Problem

Example Problem 1

In Figure 52-1 on page 1278, when any of the local processors on one FSB attempts to perform a read or write that targets memory residing on the remote FSB, it can result in very long latency during the Data Phase of the transaction.

When a memory read transaction is initiated, all of the agents on the local FSB latch the transaction and each of the local Response Agents examines the address and transaction type to determine which of them is the target. Assuming that the local processor is targeting memory on the remote FSB, the Cluster Bridge must act as the local Response Agent for the transaction. Essentially, it acts as the surrogate for the remote target which resides on the remote FSB. If the transaction is ...