Intel
®
Xeon™ Processor 5500 Series
Balanced vs. Unbalanced Memory Population Considerations
CPU
CPU
CPU
CPU
Recommended: Balanced Memory Population
●
Use a “balanced” platform configuration: populate the same number of DIMMs for each channel and each socket.
●
Use identical DIMM types throughout the platform: same size, speed, and number of ranks.
Alternatives: Unbalanced Memory Population “2-1-1” (not recommended)
Balanced 1-1-1 Memory Population
CPU
CPU
Option 1
Option 2
Population Scenario
●
Interleave the first 3 DIMMs equally across the 3 channels
and add the 4
th
DIMM to the first channel.
Performance Consideration: Unpredictable Performance
●
If your application uses only the first three DIMMs, your
results will be the same as in a balanced 1-1-1 memory
population scenario.
●
If the 4
th
DIMM is used, your performance will be reduced
to the equivalent of a single channel.
Population Scenario
●
Interleave across all four DIMMs equally.
Performance Consideration: Bandwidth Bottleneck
●
For every memory request the application makes to channels
2 and 3, channel 1 will need to handle two requests.
●
The doubled number of requests to channel 1 will result
in a bottleneck of your bandwidth.
