Virtual I/O Server - IBM REDPAPER 520Q Technical Overview And Introduction

Dispatching example with:
LPAR1 entitlement = 0.5
LPAR2 entitlement = 0.5
LPAR3 entitlement = 1.0
Figure 2-14 Logical, virtual, and physical processor mapping
In Figure 2-14, a system with four physical processors and four partitions is presented; one
partition (LPAR4) is in dedicated mode and three partitions (LPAR1, LPAR2, and LPAR3) are
running in shared mode. Dedicated mode LPAR4 is using one physical processor and, thus,
three processors are available for shared processor pool. The LPAR1 defines five virtual
processors and the simultaneous multithreading feature is on (thus, it sees 10 logical
processors). LPAR2 defines one virtual processor and simultaneous multithreading is off (one
logical processor). LPAR3 defines two virtual processors and simultaneous multithreading is
on. Currently (sample time), virtual processors 2 and 3 of LPAR1 and virtual processor 0 of
LPAR2 are dispatched on physical processors in the shared pool. Other virtual processors
are idle waiting for dispatch by the Hypervisor. When more virtual processors are defined
within a partition, any virtual processors share equal parts of the partition processing
entitlement.

2.12.3 Virtual I/O Server

The Virtual I/O Server (VIOS) is a special purpose partition that provides virtual I/O resources
to other partitions. The Virtual I/O Server owns the physical resources (actually SCSI, Fibre
Channel and network adapters, and optical devices) and allows client partitions to share
access to them, thus, minimizing the number of physical adapters in the system. The Virtual
I/O Server eliminates the requirement that every partition own a dedicated network adapter,
disk adapter, and disk drive.
Figure 2-15 on page 55 shows an organization view of a micro-partitioned system including
the Virtual I/O Server. The figure also includes virtual SCSI and Ethernet connections and
mixed operating system partitions.
54
IBM System p5 520 and 520Q Technical Overview and Introduction
LPAR1 -
shared mode
5 virual CPU's
SMT ON
virtual virtual virtual
processor processor processor processor
(VP0) (VP1) (VP2)
dispatched dispatched
physical
CPU
(proc0)
shared pool
HW - physical resources driven by Hypervisor
0
msec
Physical CPU proc0
Physical CPU proc1
Physical CPU proc2
LPAR2 -
shared mode
1 virual CPU
SMT OFF
virtual virtual virtual
processor processor
(VP3) (VP4) (VP0)
dispatched
physical
CPU
(proc1)
sample
time
LPAR1
LPAR1 LPAR3
VP0
VP2 VP0
LP0+1 LP4+5 LP0+1
LPAR1 LPAR1 LPAR1
Spare
VP2 VP3 VP4
Processing units
LP2+3 LP6+7 LP8+9
LPAR2
VP0
LP0
LPAR3 -
LPAR4 -
shared mode
dedicated
2 virual CPU's
1 physical CPU
SMT ON
SMT ON
virtual virtual
.
processor processor
(VP0) (VP1)
physical physical
CPU CPU
(proc2) (proc3)
dedicated
LPAR3 LPAR3
VP1 VP1
LP2+3 LP2+3
LPAR3
Spare
VP0
Processing units
LP0+1
Spare
Processing units
10
msec