VM65858: RELATIVE SHARE FOR GUESTS IN CPUPOOL NOT RESPECTED

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Guests relative share setting in a CPUPOOL was not being
  distributed in a fair manner.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users exploiting CPU Pools (Resource Pools)  *
  *                 and using relative SHARE settings to         *
  *                 apportion resources to guests in a pool.     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  Users in a CPU Pool (Resource Pool) do not necessarily receive
  CPU resources in proportion to their SHARE settings. While this
  behavior can occur if there are excess CPU resources available,
  in the situation where there is contention between guests in the
  pool for CPU, the actual allocation of resources to them is not
  completely controlled by their SHARE settings. This occurred
  because the logic to limit a guest has a consumption threshold
  that must be exceeded before limiting is imposed. However, if a
  guest is being scheduled and the pool is already limited, this
  threshold was still applied. This allowed the guest to run,
  causing the pool to exceed its limit even more. This resulted in
  not allocating CPU resources in accordance with SHARE settings.
  

Problem conclusion

• Code has been changed to limit a guest immediately if it belongs
  to a pool that is limited. This allows placement of guests in
  the Dispatch List according to their SHARE settings while not
  permitting excess CPU resources to be consumed when the pool is
  already limited.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UM35402 UM35422

Modules/Macros

• HCPSCI
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R640 PSY UM35402

     UP19/07/12 P 2001

• R710 PSY UM35422

     UP19/07/12 P 1902

Fix is available

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