System memory interleaving – Sun Microsystems SUN FIRE 280R User Manual

Page 109

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Chapter 4

Hardware and Software Configuration

81

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.

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.

Group

Physical Address

Bank

1

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.

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