HP-UX Virtual Partitions Administrator Guide (includes A.05.08) (5900-1312, March 2011)

CPU: Dual-Core Processors
With the PA-8800s and other dual-core processors, there are two CPUs per socket. (On a cell
board with four sockets, this allows 8 CPUs per cell board.) The CPUs that share the socket are
called sibling CPUs.
Splitting sibling CPUs across virtual partitions refers to assigning one sibling CPU to one partition
and assigning the other sibling CPU to a different virtual partition. No noticeable performance
degradation has been seen when splitting sibling CPUs. Due to items such as the larger L2 cache
size, there actually can be a small performance boost if the siblings are split such that one of the
virtual partitions has no workload. If you require consistently predictable performance, configure
the virtual partitions consistently; in other words, decide whether to split siblings or keep them
together, and maintain that policy across all virtual partitions.
Determining If the System Has Dual-Core Processors
You can see the sibling and virtual partition assignment using vparstatus -d. If you do not
have a dual-core system, the output will show dashes (-) for the sibling and assignment information:
# vparstatus -d
CPU Cell Config Sibling Information
path CPU HPA ID Status Assigned to Path /vPar name
===== ================== ==== ====== ================== =======================
0.10 0xfffffffffc078000 0 E vpuma02 - -
0.11 0xfffffffffc07a000 0 E vpuma01 - -
0.12 0xfffffffffc07c000 0 E vpuma04 - -
0.13 0xfffffffffc07e000 0 E - - -
...
When you do have dual-core system, the vparstatus -d output will look similar to the following:
# vparstatus -d
CPU Cell Config Sibling Information
path CPU HPA ID Status Assigned to Path /vPar name
===== ================== ==== ====== ================== =======================
0.10 0xfffffffffc070000 0 E vpkeira1 0.11 vpkeira3
0.11 0xfffffffffc071000 0 E vpkeira3 0.10 vpkeira1
0.12 0xfffffffffc074000 0 E - 0.13 vpkeira4
0.13 0xfffffffffc075000 0 E vpkeira4 0.12 -
0.14 0xfffffffffc078000 0 E - 0.15 -
0.15 0xfffffffffc079000 0 E - 0.14 -
...
You can also use the parstatus command or parmgr to determine if you are running dual-core
processors. If the maximum number of CPUs per cell is 8, then you are running dual-core processors:
# parstatus -c 0
[Cell]
CPU Memory Use
OK/ ( GB) Core On
Hardware Actual Deconf/ OK/ Cell Next Par
Location Usage Max Deconf Connected To Capable Boot Num
========== ============ ======= ========= =================== ======= ==== ===
cab0,cell0 active core 8/0/8 2.0/ 0.0 cab0,bay0,chassis0 yes yes 0
Figure 24 Using Partition Manager to Determine Dual-Core Processors
CPU: Dual-Core Processors 227