Resource Governor - Can a workload go beyond Calculated effective MAX % ?

  • Hi,

    I am having (another) argument with Microsoft support team. I want to check if I am crazy. 

    Here is the configuration of the pool:
    The MIN_CPU_PERCENT% setting is set to 20%
    The MAX_CPU_PERCENT % setting is set to 100%.
    The Calculated effective MAX % is 50%.

    Would you agree the the maximum CPU utilization allowed for this pool is 50%.
    Would you agree that CAP_CPU_PERCENT would have no influence for this pool?

    Thank you

  • Gamleur84 - Wednesday, March 20, 2019 11:03 PM

    Hi,

    I am having (another) argument with Microsoft support team. I want to check if I am crazy. 

    Here is the configuration of the pool:
    The MIN_CPU_PERCENT% setting is set to 20%
    The MAX_CPU_PERCENT % setting is set to 100%.
    The Calculated effective MAX % is 50%.

    Would you agree the the maximum CPU utilization allowed for this pool is 50%.
    Would you agree that CAP_CPU_PERCENT would have no influence for this pool?

    Thank you

    The maximum CPU utilisation for this pool is 100% of the CPU, because you have said MAX_CPU_PERCENT = 100 and have not defined any other pools, at least not in the information provided.

    From Docs:

    Note that the maximum CPU percentage is an opportunistic maximum. If there is available CPU capacity, the workload uses it up to 100 percent. The maximum value only applies when there is contention for CPU resources.

    With your settings, the pool would use at least 20% and up to 100% of the available CPU resources. If you set CAP_CPU_PERCENT to 50%, this is a hard limit that will prevent the pool using more than 50% of the CPU resources, even when there is no contention for CPU.

    Again, from Docs:

    This setting is a hard cap limit on the CPU bandwidth for all requests in the resource pool. Workloads associated with the pool can use CPU capacity above the value of MAX_CPU_PERCENT if it is available, but not above the value of CAP_CPU_PERCENT.

    If, however, you had another pool, and that pool had a MIN_CPU_PERCENT of 50%, then yes the maximum CPU for your original pool would be 50%. Again, from Docs:

    If a pool has a nonzero MIN defined, the effective MAX value of other pools is readjusted. The minimum of the configured MAX value of a pool and the sum of the MIN values of other pools is subtracted from 100 percent.

  • Thanks !

Viewing 3 posts - 1 through 2 (of 2 total)

You must be logged in to reply to this topic. Login to reply