Power7 Virtualization; Virtual Processors - IBM Power7 Optimization And Tuning Manual

– Shared LPAR: Weight selection to assign a level of priority to get uncapped capacity
(excess cycles to address the peak usage).
– Shared LPAR: Multiple shared pools to address software licensing costs, which
prevents a set of partitions from exceeding its capacity consumption.
– Active Memory Sharing: The size of a shared pool is based on active workload
memory consumption:
• Inactive workload memory is used for active workloads, which reduces the memory
• The Active Memory De-duplication option can reduce memory capacity further.
• AIX file system cache memory is loaned to address memory demands that lead to
• Workload load variation changes active memory consumption, which leads to
– Active Memory Sharing: A shared pool size determines the levels of memory
overcommit. Starts without overcommit and is based on workload consumption that
reduces the pool.
– Active Memory Expansion: AIX working set memory is compressed.
– Active Memory Sharing and Active Memory Expansion can be deployed on the
same workload.
– Active Memory Sharing: VIO server sizing is critical for CPU and memory.
– Virtual Ethernet: An inter-partition communication VLANs option that is used for higher
network performance.
– Shared Ethernet versus host Ethernet.
– Virtual disk I/O: Virtual small computer system interface (vSCSI), N_Port ID
Virtualization (NPIV), file-backed storage, and storage pool.
– Dynamic resource movement (DLPAR) to adopt to growth.

3.2 POWER7 virtualization

PowerVM hypervisor and the AIX operating system (AIX V6.1 TL 5 and later versions) on
POWER7 implement enhanced affinity in a number of areas to achieve optimized
performance for workloads that are running in a virtualized shared processor logical partition
(SPLPAR) environment. By using the preferred practices that are described in this guide,
customers can attain optimum application performance in a shared resource environment.
This guide covers preferred practices in the context of POWER7 Systems, so this section can
be used as an addendum to other PowerVM preferred practice documents.

3.2.1 Virtual processors

A virtual processor is a unit of a virtual processor resource that is allocated to a partition or
virtual machine. PowerVM hypervisor can map a whole physical processor core, or it can
create a time slice of a physical processor core.
PowerVM hypervisor create time slices of Micro-Partitioning on physical CPUs by dispatching
and undispatching the various virtual processors for the partitions that are running in the
shared pool.
capacity of the pool.
memory savings.
opportunity for sharing.
Chapter 3. The POWER Hypervisor
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