User`s guide

30 SGI
®
Altix
®
XE210 User’s Guide
Performance Optimization
The primary rule for installing DIMMs to obtain maximum performance is the following:
Balance the DIMM memory capacity across both memory branches.
As illustrated in Figure 21, the MCH has memory Branch 0 and Branch 1. DIMMs A1,
A2, B1, and B2 are on Branch 0 and DIMMs C1, C2, D1, and D2 are on Branch 1. If the
total memory capacity of the DIMMs on each branch is not balanced, the memory
performance will be degraded by approximately 25% and , in some cases, 40%.
Table 3 lists the recommended DIMM configurations to achieve maximum performance.
Table 3. Recommended DIMM Configurations
Note: DIMM configurations that are not described in Table 3 will run with degraded
performance.
The following are examples of DIMM configurations that will yield degraded
performance:
• Single DIMM pair
• Three DIMM pairs all having the same memory capacity
DIMM Pair 1
Capacity
DIMM Pair 2
Capacity
DIMM Pair 3
Capacity
DIMM Pair 4
Capacity
Total Node
Memory Size
2GB
2GB
4GB
4GB
4GB
8GB
2GB
2GB
2GB 2GB 8GB
4GB
2GB
2GB 8GB (mixed)
4GB
4GB
2GB 2GB 12GB (mixed)
8GB
8GB
16GB
4GB
4GB
4GB 4GB 16GB
8GB
4GB
4GB 16GB (mixed)
8GB
8GB
2GB 2GB 20GB (mixed)
8GB
8GB
4GB 4GB 24GB (mixed)
8GB
8GB
8GB 8GB 32GB