126 IBM Power 750 and 760 Technical Overview and Introduction
Shared mode
In shared mode, logical partitions use virtual processors to access fractions of physical
processors. Shared partitions can define any number of virtual processors (the maximum
number is 10 times the number of processing units that are assigned to the partition). From
the POWER Hypervisor perspective, virtual processors represent dispatching objects. The
POWER Hypervisor dispatches virtual processors to physical processors according to the
partition’s processing units entitlement. One processing unit represents one physical
processor’s processing capacity. At the end of the POWER Hypervisor’s dispatch cycle
(10 ms), all partitions receive total CPU time equal to their processing unit’s entitlement. The
logical processors are defined on top of virtual processors. So, even with a virtual processor,
the concept of a logical processor exists and the number of logical processors depends
whether the simultaneous multithreading is turned on or off.
3.4.3 Multiple shared processor pools
Multiple shared processor pools (MSPPs) is a capability that is supported on POWER6,
POWER6+, POWER7, and POWER7+ processor-based servers. This capability allows a
system administrator to create a set of micropartitions with the purpose of controlling the
processor capacity that can be consumed from the physical shared processor pool.
Implementing MSPPs depends on a set of underlying techniques and technologies.
Figure 3-8 shows an overview of the architecture of multiple shared processor pools.
Figure 3-8 Overview of the architecture of multiple shared processor pools
POWER Hypervisor
p1p0
Physical Shared-Processor Pool
p2 p3 p4 p5 p6 p7
Shared Processor Pool
0
Set of micro-partitions
AIX V5.3
EC 1.6
AIX V6.1
EC 0.8
Linux
EC 0.5
vp0
vp1
vp2 vp3
vp4
AIX V6.1
EC 1.6
AIX V6.1
EC 0.8
Linux
EC 0.5
vp5
vp6
vp7
vp8 vp9
vp10
Shared Processor Pool
1
Set of micro-partitions
Unused capacity in SPP
0
is
redistributed to uncapped
micro-partitions within SPP
0
Unused capacity in SPP
1
is
redistributed to uncapped
micro-partitions within SPP
1
KEY:
EC Entitled Capacity
p Physical processor
vp Virtual processor
SPPn Shared-Processor Pool
n
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