Chapter 3. Virtualization
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Table 3-2 lists the differences between these modes.
Table 3-2 Differences between POWER6, , and POWER7 compatibility mode
3.3 Active Memory Expansion
Active Memory Expansion enablement is an optional feature of POWER7 and
processor-based servers that must be specified using FC 4792 when creating the
configuration in the e-Config tool.
This feature enables memory expansion on the system. Using compression and
decompression of memory content can effectively expand the maximum memory capacity,
providing additional server workload capacity and performance.
Active Memory Expansion is a POWER technology that allows the effective maximum
memory capacity to be much larger than the true physical memory maximum. Compression
and decompression of memory content can allow memory expansion up to 125% for AIX
partitions, which in turn enables a partition to perform significantly more work or support more
users with the same physical amount of memory. Similarly, it can allow a server to run more
partitions and do more work for the same physical amount of memory.
Active Memory Expansion is available for partitions running AIX 6.1, Technology Level 4 with
SP2, or later.
Active Memory Expansion uses the CPU resource of a partition to compress and decompress
the memory contents of this same partition. The trade-off of memory capacity for processor
cycles can be an excellent choice, but the degree of expansion varies based on how
POWER6 and
mode
POWER7
mode
Customer value
2-thread SMT
4-thread SMT
Throughput performance,
processor core utilization
Vector Multimedia Extension/
AltiVec (VMX)
Vector scalar extension (VSX)
High-performance computing
Affinity OFF by default
3-tier memory, Micropartition
Affinity, Dynamic Platform
Optimizer
Improved system performance
for system images spanning
sockets and nodes
Barrier Synchronization
Fixed 128-byte array,
Kernel Extension Access
Enhanced Barrier
Synchronization
Variable Sized Array, User
Shared Memory Access
High-performance computing
parallel programming
synchronization facility
64-core and 128-thread scaling
32-core and 128-thread
scaling
64-core and 256-thread
scaling
128-core and 512-thread
scaling
256-core and 1024-thread
scaling
Performance and scalability for
large scale-up single system
image workloads (such as
OLTP, ERP scale-up, and
WPAR consolidation)
EnergyScale CPU Idle
EnergyScale CPU Idle and
Folding with NAP and SLEEP
Improved energy efficiency
