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HP-UX Virtual Partitions Administrator’s Guide > Chapter 6 CPU, Memory, and I/O Resources (A.05.xx)

CPU: Dual-Core Processors

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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 6-7 Using Partition Manager to Determine Dual-Core Processors

Using Partition Manager to Determine Dual-Core Processors

Determining Sibling CPUs

Once you have determined that you have a dual-core system, the siblings have adjacent hardware paths. The first core’s path ends in an even number, and its sibling’s path ends in the following (odd) number. For example, if the ioscan output shows:

0/10 processor Processor 0/11 processor Processor 0/12 processor Processor 0/13 processor Processor 0/14 processor Processor 0/15 processor Processor 0/16 processor Processor 0/17 processor Processor

The hardware paths for the sibling pairs are

0/10 and 0/11 0/12 and 0/13 0/14 and 0/15 0/16 and 0/17

After vPars is installed, you can also use the vPars Monitor’s scan command to show hardware paths.

MON> scan 0 CELL sv_model=172 HPA=0xfffffffffc000000 VPAR=ALL 0/0 BUSCONV sv_model= 12 HPA=0xffffff8020000000 VPAR=ALL 0/0/0 BUS_BRIDGE sv_model= 10 HPA=0xffffff8010000000 VPAR=vpar1 0/0/1 BUS_BRIDGE sv_model= 10 HPA=0xffffff8010002000 VPAR=vpar1 0/0/2 BUS_BRIDGE sv_model= 10 HPA=0xffffff8010004000 VPAR=NONE 0/0/4 BUS_BRIDGE sv_model= 10 HPA=0xffffff8010008000 VPAR=NONE 0/0/6 BUS_BRIDGE sv_model= 10 HPA=0xffffff801000c000 VPAR=NONE 0/0/8 BUS_BRIDGE sv_model= 10 HPA=0xffffff8010010000 VPAR=vpar4 0/0/10 BUS_BRIDGE sv_model= 10 HPA=0xffffff8010014000 VPAR=vpar2 0/0/12 BUS_BRIDGE sv_model= 10 HPA=0xffffff8010018000 VPAR=NONE 0/0/14 BUS_BRIDGE sv_model= 10 HPA=0xffffff801001c000 VPAR=vpar3 0/5 MEMORY sv_model= 9 HPA=0xfffffffffc016000 VPAR=ALL 0/10 NPROC sv_model= 4 HPA=0xfffffffffc070000 VPAR=vpar2 0/11 NPROC sv_model= 4 HPA=0xfffffffffc071000 VPAR=vpar3 0/14 NPROC sv_model= 4 HPA=0xfffffffffc078000 VPAR=vpar4 0/15 NPROC sv_model= 4 HPA=0xfffffffffc079000 VPAR=SHARED 1 CELL sv_model=172 HPA=0xfffffffffc080000 VPAR=ALL 1/0 BUSCONV sv_model= 12 HPA=0xffffff8120000000 VPAR=ALL 1/0/0 BUS_BRIDGE sv_model= 10 HPA=0xffffff8110000000 VPAR=vpar1 1/0/1 BUS_BRIDGE sv_model= 10 HPA=0xffffff8110002000 VPAR=vpar1 1/0/2 BUS_BRIDGE sv_model= 10 HPA=0xffffff8110004000 VPAR=vpar4 1/0/4 BUS_BRIDGE sv_model= 10 HPA=0xffffff8110008000 VPAR=NONE 1/0/6 BUS_BRIDGE sv_model= 10 HPA=0xffffff811000c000 VPAR=vpar2 1/0/8 BUS_BRIDGE sv_model= 10 HPA=0xffffff8110010000 VPAR=NONE 1/0/10 BUS_BRIDGE sv_model= 10 HPA=0xffffff8110014000 VPAR=vpar3 1/0/12 BUS_BRIDGE sv_model= 10 HPA=0xffffff8110018000 VPAR=vpar1 1/0/14 BUS_BRIDGE sv_model= 10 HPA=0xffffff811001c000 VPAR=NONE 1/5 MEMORY sv_model= 9 HPA=0xfffffffffc096000 VPAR=ALL 1/6 IPMI sv_model=192 HPA=0xfffffffc300c0000 VPAR=ALL 1/10 NPROC sv_model= 4 HPA=0xfffffffffc0f0000 VPAR=vpar1 1/11 NPROC sv_model= 4 HPA=0xfffffffffc0f1000 VPAR=SHARED 1/14 NPROC sv_model= 4 HPA=0xfffffffffc0f8000 VPAR=SHARED 1/15 NPROC sv_model= 4 HPA=0xfffffffffc0f9000 VPAR=SHARED

where the following CPU pairs are siblings:

  • CPU 1/10 (owned by vpar1) and CPU 1/11 (unassigned)

  • CPU 0/10 (owned by vpar2) and CPU 0/11 (owned by vpar3)

  • CPU 0/14 (owned by vpar4) and CPU 0/15 (unassigned)

  • CPU 1/14 (unassigned) and CPU 1/15 (unassigned)

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