Network Topology Aware Plugin

[lowang-bh]

/kind feature
fixes #2984
fixes #447
fixes #3317
There are several issues request this feature, such as #447 #2984 #3317

Motivation

We target to make scheduler net-topology aware so as to achieve the following:

• best effort to schedule same job to same topology devices, such as same idc.

Goals

• Support single key topology configuration, try to schedule job's all tasks to nodes which have same value with that key
• Support multiple-key topology policies, the key at front get higher score

Non-Goals

• Not to find the global solutions among nodes with all kind values of that key

[lowang-bh]

/assign @Monokaix @hwdef @william-wang

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[hwdef]

we should talk this in weekly meeting.

[Thor-wl]

Sounds interesting！But it's maybe more complex than the given desgin. For example, network delay varies between different nodes. Also, it varies in different period to the same node. Maybe considering with network performance metrics for this feature will be a good choice. I think we should take a discussion in the community and complete the design first.

[Monokaix]

What's the difference between this and https://github.com/kubernetes-sigs/scheduler-plugins/tree/master/pkg/networkaware？

[lowang-bh]

Maybe considering with network performance metrics for this feature will be a good choice.

I would like to recommend to treat the network performace metrics as a kind of load, so it's more like a loadaware scheduling.

network delay varies between different nodes

Now it is not considered. This plugin just conserder the physical difference in topology.

[lowang-bh]

https://github.com/kubernetes-sigs/scheduler-plugins/tree/master/pkg/networkaware？

I think it is a lite one of that plugin, just consider several physical topology, such as idc, rock, switch, and depend on those labels on nodes.

advantage: more simply to use, just rely on node labels
shortcoming：no bandwidth, no latency, etc.

[Monokaix]

https://github.com/kubernetes-sigs/scheduler-plugins/tree/master/pkg/networkaware？

I think it is a lite one of that plugin, just consider several physical topology, such as idc, rock, switch, and depend on those labels on nodes.

advantage: more simply to use, just rely on node labels shortcoming：no bandwidth, no latency, etc.

We should collect more user cases: )

[Monokaix]

From the original user demand, job should occupy nodes exclusively, so only nodeorder func seems cannot satisfy the original use case.

[lowang-bh]

You mean a predicateFn is need?