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update doc for kubelet option --reserved-cpus (#17648)

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This commit is contained in:
Jianzhu Zhang
2019-11-27 11:57:21 -05:00
committed by Bob Killen
parent 6fde238d15
commit fe6087b601
2 changed files with 32 additions and 3 deletions
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content/en/docs/tasks/administer-cluster/reserve-compute-resources.md
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@@ -146,6 +146,28 @@ control group (`system.slice` on systemd machines for example).
Note that Kubelet **does not** create `--system-reserved-cgroup` if it doesn't
exist. Kubelet will fail if an invalid cgroup is specified.
### Explictly Reserved CPU List
{{< feature-state for_k8s_version="v1.17" state="stable" >}}
- **Kubelet Flag**: `--reserved-cpus=0-3`
`reserved-cpus` is meant to define an explict CPU set for OS system daemons and
kubernetes system daemons. This option is added in 1.17 release. `reserved-cpus`
is for systems that do not intent to define seperate top level cgroups for
OS system daemons and kubernetes system daemons with regard to cpuset resource.
If the Kubelet **does not** have `--system-reserved-cgroup` and `--kube-reserved-cgroup`,
the explicit cpuset provided by `reserved-cpus` will take precedence over the CPUs
defined by `--kube-reserved` and `--system-reserved` options.
This option is specifically designed for Telco/NFV use cases where uncontrolled
interrupts/timers may impact the workload performance. you can use this option
to define the explict cpuset for the system/kubernetes daemons as well as the
interrupts/timers, so the rest CPUs on the system can be used exclusively for
workloads, with less impact from uncontrolled interrupts/timers. To move the
system daemon, kubernetes daemons and interrupts/timers to the explict cpuset
defined by this option, other mechanism outside Kubernetes should be used.
For example: in Centos, you can do this using the tuned toolset.
### Eviction Thresholds
- **Kubelet Flag**: `--eviction-hard=[memory.available<500Mi]`
@@ -259,4 +281,8 @@ for `kube-reserved` and `system-reserved`.
As of Kubernetes version 1.8, the `storage` key name was changed to `ephemeral-storage`
for the alpha release.
As of Kubernetes version 1.17, you can optionally specify
explicit cpuset by `reserved-cpus` as CPUs reserved for OS system
daemons/interrupts/timers and Kubernetes daemons.
{{% /capture %}}