A fix is available
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 number
VM65858
Reported component name
VM CP
Reported component ID
568411202
Reported release
640
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-06-14
Closed date
2019-07-02
Last modified date
2020-12-16
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
Fix is available
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Document Information
Modified date:
12 January 2021