Topic
IC4NOTICE: developerWorks Community will be offline May 29-30, 2015 while we upgrade to the latest version of IBM Connections. For more information, read our upgrade FAQ.
4 replies Latest Post - ‏2013-03-06T00:01:19Z by SystemAdmin
SystemAdmin
SystemAdmin
2402 Posts
ACCEPTED ANSWER

Pinned topic Nmon - PCPU_ALL,SCPU_ALL and CPU_ALL tags

‏2013-02-22T00:41:21Z |
Hello all,

I've been reading the nmon analyzer documentation and browsing the IBM forum, however I am unable to find any resources that can explain to me the difference between the following tags below.
PCPU_ALL SCPU_ALL and CPU_ALL.

Can anyone share their insight/knowledge in this area?
preferrably with a couple of examples.

Thanks,
Peter H
Updated on 2013-03-06T00:01:19Z at 2013-03-06T00:01:19Z by SystemAdmin
  • puvichakravarthy
    puvichakravarthy
    55 Posts
    ACCEPTED ANSWER

    Re: Nmon - PCPU_ALL,SCPU_ALL and CPU_ALL tags

    ‏2013-02-26T18:57:01Z  in response to SystemAdmin
    PCPU_ALL is the actual physical resource consumption . It would be in units of cores.
    SCPU_ALL is the scaled physical resource consumption. Differs from PCPU_ALL if running at non-nominal frequency.Again in units of cores.

    Kindly refer to the lparstat article in this wiki.

    https://www.ibm.com/developerworks/mydeveloperworks/wikis/home?lang=en#/wiki/Power%20Systems/page/Performance%20Tools
    • SystemAdmin
      SystemAdmin
      2402 Posts
      ACCEPTED ANSWER

      Re: Nmon - PCPU_ALL,SCPU_ALL and CPU_ALL tags

      ‏2013-03-01T02:02:09Z  in response to puvichakravarthy
      I don't believe that PCPU_ALL is in CPU cores, Unless it has something to do with the fractions of a CPU allocated during a timeslice.

      I have the following tags and samples below.

      CPU_ALL,CPU Total mylpar,User%,Sys%,Wait%,Idle%,Busy,PhysicalCPUs
      PCPU_ALL,PCPU Total mylpar,User ,Sys ,Wait ,Idle , Entitled Capacity
      SCPU_ALL,SCPU Total mylpar,User ,Sys ,Wait ,Idle
      LPAR,Logical Partition LPAR,Logical Partition mylpar,PhysicalCPU,virtualCPUs,logicalCPUs,poolCPUs,entitled,weight,PoolIdle,usedAllCPU%,usedPoolCPU%,SharedCPU,Capped,EC_User%,EC_Sys%,EC_Wait%,EC_Idle%,VP_User%,VP_Sys%,VP_Wait%,VP_Idle%,Folded,Pool_id

      CPU_ALL,T0422,7.3,51.4,0.7,40.6,,8
      PCPU_ALL,T0422,0.03,0.19,0.0,0.15,0.20
      SCPU_ALL,T0422,0.03,0.19,0.0,0.15
      LPAR,T0422,0.376,2,8,24,0.20,128,0.00,1.57,1.57,1,0,13.76,96.51,1.27,76.30,1.38,9.65,0.13,7.63,0,0

      I know that the LPAR tag value of 0.376 represents the true Physical CPU cores consumed our of the 24 CPUs in the box.... The value is vastly different from SCPU_ALL value 0f 0.03. The link you provided does not appear to distinguish between the various CPU,PCPU and SCPU tags at all.

      Here is a little more detail on the server.

      BBBL,03,CPU in sys,24
      BBBL,04,Virtual CPU,2
      BBBL,05,Logical CPU,8
      BBBL,06,Pool CPU,24
      BBBL,07,smt threads,4
      BBBL,08,capped,0
      BBBL,09,min Virtual,1
      BBBL,10,max Virtual,2
      BBBL,11,min Logical,1
      BBBL,12,max Logical,8
      BBBL,13,min Capacity,0.1
      BBBL,14,max Capacity,0.2
      • puvichakravarthy
        puvichakravarthy
        55 Posts
        ACCEPTED ANSWER

        Re: Nmon - PCPU_ALL,SCPU_ALL and CPU_ALL tags

        ‏2013-03-01T05:56:14Z  in response to SystemAdmin
        Thanks for the data. Like I mentioned, SCPU, PCPU do not differ when the system runs in the nominal frequency.

        Also, the PhysicalCPU tag (0.376) denotes the fraction of core used by this partition. The distribution of the 0.376 across various modes ( user, sys, wait, idle ) is proportional to the CPU_ALL% in all modes. Applying this % would give the PCPU_ALL.

        Also, the Physical CPU usage of 0.376 is what is consumed by the partition. It should equate to PCPU_ALL across all modes (0.03user + 0.19sys + 0.0 wait + 0.15idle)

        I believe this is the only partition with any load on the system. (PoolCPUs of 24 indicate that all CPUs in the system has been allocated to a global pool. usedPoolCPU% of 1.57%
        (1.57/100) * 24 ~= 0.37 which is the CPUs used by this partition.)
        • SystemAdmin
          SystemAdmin
          2402 Posts
          ACCEPTED ANSWER

          Re: Nmon - PCPU_ALL,SCPU_ALL and CPU_ALL tags

          ‏2013-03-06T00:01:19Z  in response to puvichakravarthy
          Ahh.. Excellent.
          0.01+0.19+0+0.15 = 0.37 Close enough to the 0.376 cores actually consumed by the LPAR (I didn't realise this was the cumulative sum until you pointed it out Thanks!!)

          It is clear now.

          Extra notes for clarity:
          There are multiple lpars/micropartitions on the box.. not just one.
          The 1.57% as you have correctly mentioned is just a percentage of how much CPU the micropartition is consuming from the whole box, because this LPAR is in the default pool.

          Cheers,
          Peter