Sun Microsystems 280R manual System Memory Interleaving

System Memory Interleaving

CPU processing rate is slowed by memory module response time, and limited by the word size (64 bytes) of its read or write requests—referred to as the processing stride. System memory interleaving is a technique to increase CPU throughput by splitting the memory system into independent banks that answer CPU read or write requests independently and in parallel.

Main memory on the Sun Fire 280R server supports interleaving across all eight slots on 64-byte boundaries, and the memory system can support from one to four logical banks. The processing stride at 64 bytes produces no interleaving, at 128 bytes it produces two-way interleaving, and at 256 bytes it produces four-way interleaving. The Sun Fire 280R system is limited to four-way interleaving. The group addresses are listed in the following table.

Group	Physical Address	Bank1
1	J0407	1
0	J0406	0
1	J0305	1
0	J0304	0
1	J0203	3
0	J0202	2
1	J0101	3
0	J0100	2

1 Logical banks are created on the DIMM.

For interleaving purposes, all banks are treated identically regardless of their physical location. Two successive accesses to distinct logical banks located in the same group of DIMMs are processed the same as accesses to logical banks that are in separate groups of DIMMs.

Chapter 4 Hardware and Software Configuration 81