Patrol for Unix and Linux (PUK) - Questions relating to CPUCpuUtil, CPUEntlUtil, and CPUPoolUtil in AIX micropartion (SPLPAR) environment.

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    PRODUCT:

    BMC Performance Manager for Servers


    COMPONENT:

    PATROL for Unix and Linux


    APPLIES TO:

    BMC Performance Manager for Servers



    QUESTION:

     
       PATROL Knowledge Module for Unix (All versions starting with 9.3.00)  
       
       DR: BMC Performance Manager Integration with PATROL for UNIX and Linux; Server: AIX 5.x; Client: Windows; HW: IBM RS6000; Language: English-USA;  


    ANSWER:

     

    Questions relating to CPUCpuUtil, CPUEntlUtil, and CPUPoolUtil in AIX micropartion (SPLPAR) environment:

      

    Is the CPUCpuUtil LPAR specific?
    Is the CPUPoolUtil giving metrics on the virtual machine? Or the LPAR?
    What about CPUEntlUtil? 

      

    Answer:

      

    CPUCpuUtil provides percentage of CPU utilization available to the host on
    which the PatrolAgent is running.  This is 0-100%.

      

    CPUEntlUtil displays the CPU utilization as a percentage of processing capacity "entitled" to the partition
    Note: This parameter appears only in the AIX micropartitioned environment.
    page 65

      

    This parameter displays AIX SPLPAR CPU Utilization as a percentage of processing capacity "entitled" to the partition. The range for CPUEntlUtil parameter for capped and uncapped AIX SPLPAR is as follows:

      

    CAPPED: 0 - 100 percent
    UNCAPPED: 0 - x * 100 percent (where x = number of Physical processors in the shared pool or Virtual processors, which ever is smaller / Entitlement)

      

    CPUPoolUtil displays the CPU utilization as a percentage of processing
    capacity in the shared processor pool

      

    This parameter displays AIX SPLPAR CPU Utilization as a percentage of processing capacity "entitled" to the partition. The range for CPUEntlUtil parameter for capped and uncapped AIX SPLPAR is as follows:

      

    CAPPED: 0 - 100 percent
    UNCAPPED: 0 - x * 100 percent (where x = number of Physical processors in the shared pool or Virtual processors, which ever is smaller / Entitlement)

      

    Related information:

      

    In an SPLPAR environment, each partition may have one or more virtual processors
    assigned to it - the number of virtual processors configured for a partition is
    less than or equal to the number of physical processors available in the shared
    processor pool. Though each partition has its own virtual processors, it needs
    to be understood that these virtual processors share the same underlying
    processing resource (i.e. physical processor) available in the shared processor
    pool.

      

    The processing power of a partition can be conceptualized as being spread equally
    across its virtual processors. Thus if a SPLPAR has entitlement of 0.5 cpus and
    there are 5 virtual processors, then 0.5 cpus is spread across equally among all
    the 5 virtual processors.

      

    Configuring the number of Virtual Processors for a partition has to do with how
    the workload for that partition needs to be managed and selecting the optimal
    number of virtual processors depends on the nature of the workload. If the
    workload on a partition is such that it will benefit from greater concurrency,
    assigning more number of virtual processors to the partition may lead to
    performance improvement. On the other hand, if the nature of workload is
    such that it is does not involve any parallelism, then increasing the number
    of virtual processors may not lead to any perfomance gains and rather end up
    degrading performance rather than improving it.

      

    So if the customer needs to monitor the condition wherein the
    CASE A] The Entire server [i.e. all SPLPAR partitions that use the same shared
    proecessor pool] reaches 80 %

      

    The Customer should use the "CPUSharedPoolIdleTimeNorm" parameter in the CPU.KM
    with appropriate alarm ranges. Please note that this parameter will be available
    only on those SPLPAR Partitions that have the Shared Pool Authority.

      

    CASE B] The SPLPAR Partiton reaches 80% of the 4 assigned virtual cpus.
    The Customer should use the CPUCpuUtil or CPUEntlUtil parameters to set up
    appropriate alarm ranges. Some calculation that may help clarify what I mean :

      

    CPUCpuUtil = CPUPhyUtil/VIREntitlement (max value is 100%)
    CPUEntlUtil = CPUPhyUtil/VIREntitlement (max value can be greater 100%)

      

    Now, each Virtual processor corresponds to one SMP instance.
    CPUPhyUtil = sum of (SMPUserPercent + SMPSystemPrcnt) for all SMP instances.

    values are taken from lparstat command, this returns %user and %sys that are stored on SMPUserPercent and SMPSystemPrcnt respectively. Value for VIREntitlement is picked from ent result.
    https://www.ibm.com/support/knowledgecenter/en/ssw_aix_72/l_commands/lparstat.html

     


    Article Number:

    000252290


    Article Type:

    FAQ/Procedural



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