====== AIX CPU tuning ======

===== AIX CPU affinity =====

Affinity:
<cli prompt='#'>
[root@labo]/root#  lssrad -va
REF1   SRAD        MEM      CPU
0
          0   109259.62      0-47
[root@labo]/root# mpstat -d 5 2
System configuration: lcpu=48 ent=3.0 mode=Uncapped

cpu     cs    ics  bound     rq   push S3pull  S3grd  S0rd  S1rd  S2rd  S3rd  S4rd  S5rd   ilcs   v
  0   2049    478      1      4      0      0      0  79.1   0.4   0.0  20.5   0.0   0.0    100

[root@labo]/root# hvlpconfigdata -affinity -domain
</cli>

===== AIX mutlithreading usage =====

On Power servers, all threads on a core haven't the same power. The first are more powerful than latest. Then when you use the firsts it will be more efficient.\\
On AIX 7.1 the default is auto (0). To use less cores (development LPARs, recommended value 4), 4 threads used on 1 core before using the next core. DO NOT change to 1 !

To change this value and list the result:
<cli prompt='#'>
[root@labo]/root# schedo -o vpm_throughput_mode=4
Setting vpm_throughput_mode to 4
[root@labo]/root# schedo -o vpm_throughput_mode
vpm_throughput_mode = 4
</cli>

===== Difference between pcpu / scpu =====

scpu take care to CPU frequency changes.