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https://issues.apache.org/jira/browse/MESOS-1718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15733469#comment-15733469
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Alexander Rukletsov commented on MESOS-1718:
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If {{--cgroups_enable_cfs}} is enabled, the overcommit because of unaccounted
executor CPU resources may effectively defeat the CFS limits, depeniding on the
ratio of task's CPU to executor's.
Consider the following scenario. A framework attempts to run numerous small
command-based computationally intensive tasks with {{0.1}} CPU requirement
each. Since the allocator does not account extra resources, it is possible to
schedule {{10}} such tasks per physical CPU on one agent. However those extra
resource do increase the CFS quota, which is effectively {{0.2 × CFS period}}
per task. I would argue this can be surprising and undesirable in some cases.
> Command executor can overcommit the slave.
> ------------------------------------------
>
> Key: MESOS-1718
> URL: https://issues.apache.org/jira/browse/MESOS-1718
> Project: Mesos
> Issue Type: Bug
> Components: agent
> Reporter: Benjamin Mahler
>
> Currently we give a small amount of resources to the command executor, in
> addition to resources used by the command task:
> https://github.com/apache/mesos/blob/0.20.0-rc1/src/slave/slave.cpp#L2448
> {code: title=}
> ExecutorInfo Slave::getExecutorInfo(
> const FrameworkID& frameworkId,
> const TaskInfo& task)
> {
> ...
> // Add an allowance for the command executor. This does lead to a
> // small overcommit of resources.
> executor.mutable_resources()->MergeFrom(
> Resources::parse(
> "cpus:" + stringify(DEFAULT_EXECUTOR_CPUS) + ";" +
> "mem:" + stringify(DEFAULT_EXECUTOR_MEM.megabytes())).get());
> ...
> }
> {code}
> This leads to an overcommit of the slave. Ideally, for command tasks we can
> "transfer" all of the task resources to the executor at the slave / isolation
> level.
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