OK, so you installed AIX 7.2 TL2 SP2 on an LPAR running on your shiny, new POWER9 system.

# oslevel -s

7200-02-02-1810

# lsconf

System Model: IBM,9009-22A

Machine Serial Number: 9999999

Processor Type: PowerPC_POWER9

Processor Implementation Mode: No Data Available

Processor Version: No Data Available

Number Of Processors: 2

Processor Clock Speed: 2500 MHz

CPU Type: 64-bit

Kernel Type: 64-bit

LPAR Info: 48 l0790p046

Memory Size: 4096 MB

Good Memory Size: 4096 MB

Platform Firmware level: VL910_059

Firmware Version: IBM,FW910.00 (VL910_059)

Console Login: enable

Auto Restart: true

Full Core: false

NX Crypto Acceleration: Capable and Enabled

…

# lparstat -i

Node Name : orion

Partition Name : orion

Partition Number : 48

Type : Shared-SMT-4

Mode : Uncapped

Entitled Capacity : 0.40

Partition Group-ID : 32816

Shared Pool ID : 0

Online Virtual CPUs : 2

Maximum Virtual CPUs : 2

Minimum Virtual CPUs : 1

Online Memory : 4096 MB

Maximum Memory : 4096 MB

Minimum Memory : 1024 MB

Variable Capacity Weight : 128

Minimum Capacity : 0.10

Maximum Capacity : 0.40

Capacity Increment : 0.01

Maximum Physical CPUs in system : 20

Active Physical CPUs in system : 20

Active CPUs in Pool : 20

Shared Physical CPUs in system : 20

Maximum Capacity of Pool : 2000

Entitled Capacity of Pool : 2000

Unallocated Capacity : 0.00

Physical CPU Percentage : 20.00%

Unallocated Weight : 0

Memory Mode : Dedicated

Total I/O Memory Entitlement : -

Variable Memory Capacity Weight : -

Memory Pool ID : -

Physical Memory in the Pool : -

Hypervisor Page Size : -

Unallocated Variable Memory Capacity Weight: -

Unallocated I/O Memory entitlement : -

Memory Group ID of LPAR : -

Desired Virtual CPUs : 2

Desired Memory : 4096 MB

Desired Variable Capacity Weight : 128

Desired Capacity : 0.40

Target Memory Expansion Factor : -

Target Memory Expansion Size : -

Power Saving Mode : Dynamic Power Savings (Favor Performance)

Sub Processor Mode : -

Then, IBM released AIX 7.2 TL3 (last week). Before applying the new TL, you did a little research and reading about TL3. You find the following information:

“For POWER9 technology-based servers, the default SMT setting for AIX 7.2 TL 3 has been changed to SMT8 to provide the best out-of-the-box performance experience. For POWER8 technology-based servers, the default SMT setting remains SMT4.”

https://www-01.ibm.com/common/ssi/cgi-bin/ssialias?infotype=AN&subtype=CA&htmlfid=897/ENUS218-381&appname=USN

You check your current, TL2 system, and find that you have the default SMT setting in the LPAR i.e. SMT4.

# smtctl

This system is SMT capable.

This system supports up to 8 SMT threads per processor.

SMT is currently enabled.

SMT boot mode is not set.

SMT threads are bound to the same virtual processor.

proc0 has 4 SMT threads.

Bind processor 0 is bound with proc0

Bind processor 1 is bound with proc0

Bind processor 2 is bound with proc0

Bind processor 3 is bound with proc0

proc8 has 4 SMT threads.

Bind processor 4 is bound with proc8

Bind processor 5 is bound with proc8

Bind processor 6 is bound with proc8

Bind processor 7 is bound with proc8

OK, fine. So will my SMT setting really change, from 4 to 8, after I install TL3? Well, let’s find out.

You apply TL3 and reboot the LPAR. ‘Lo and behold’, the LPAR has automatically changed from SMT4 to SMT8. Wow!

# oslevel -s

7200-03-01-1838

# uptime

11:01PM up 1 min, 1 user, load average: 2.12, 0.75, 0.28

# smtctl

This system is SMT capable.

This system supports up to 8 SMT threads per processor.

SMT is currently enabled.

SMT boot mode is not set.

SMT threads are bound to the same virtual processor.

proc0 has 8 SMT threads.

Bind processor 0 is bound with proc0

Bind processor 1 is bound with proc0

Bind processor 2 is bound with proc0

Bind processor 3 is bound with proc0

Bind processor 4 is bound with proc0

Bind processor 5 is bound with proc0

Bind processor 6 is bound with proc0

Bind processor 7 is bound with proc0

proc8 has 8 SMT threads.

Bind processor 8 is bound with proc8

Bind processor 9 is bound with proc8

Bind processor 10 is bound with proc8

Bind processor 11 is bound with proc8

Bind processor 12 is bound with proc8

Bind processor 13 is bound with proc8

Bind processor 14 is bound with proc8

Bind processor 15 is bound with proc8

Also, you notice that the processor implementation type and version, are now reporting correctly! Before TL3, they both reported ‘No Data Available’ with lsconf.