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https://issues.apache.org/jira/browse/MESOS-9691?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benjamin Mahler reassigned MESOS-9691:
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Assignee: Benjamin Mahler
> Quota headroom calculation is off when subroles are involved.
> -------------------------------------------------------------
>
> Key: MESOS-9691
> URL: https://issues.apache.org/jira/browse/MESOS-9691
> Project: Mesos
> Issue Type: Bug
> Components: allocation
> Reporter: Meng Zhu
> Assignee: Benjamin Mahler
> Priority: Critical
> Labels: resource-management
>
> Quota "availableHeadroom" calculation:
> https://github.com/apache/mesos/blob/6276f7e73b0dbe7df49a7315cd1b83340d66f4ea/src/master/allocator/mesos/hierarchical.cpp#L1751-L1754
> is off when subroles are involved.
> Specifically, in the formula
> {noformat}
> available headroom = total resources - allocated resources - (total
> reservations - allocated reservations) - unallocated revocable resources
> {noformat}
> The "allocated resources" part is hierarchical-aware and aggregate that
> across all roles, thus allocations to subroles will be counted multiple times
> (in the case of "a/b", once for "a" and once for "a/b").
> The "total reservations" is correct, since today it is "flat" (reservations
> made to "a/b" are not counted to "a"). Thus all reservations are only counted
> once -- which is the correct semantic here. However, once we fix MESOS-9688
> (which likely requires reservation tracking to be hierarchical-aware), we
> need to ensure that the accounting is still correct.
> The "allocated reservations" is hierarchical-aware, thus overlap accounting
> would occur.
> Basically, when calculating the available headroom, we need to ensure
> "single-counting". Ideally, we only need to look at the root's consumptions.
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