Avi Kivity wrote:
Bharata B Rao wrote:
2. Need for hard limiting CPU resource
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- Pay-per-use: In enterprise systems that cater to multiple clients/customers
where a customer demands a certain share of CPU resources and pays only
that, CPU hard limits will be useful to hard limit the customer's job
to consume only the specified amount of CPU resource.
- In container based virtualization environments running multiple containers,
hard limits will be useful to ensure a container doesn't exceed its
CPU entitlement.
- Hard limits can be used to provide guarantees.
How can hard limits provide guarantees?
Hard limits are useful and desirable in situations where we would like
to maintain deterministic behavior.
Placing a hard cap on the cpu usage of a given task group (and
configuring such that this cpu time is not overcommited) on a system
allows us to create a hard guarantee that throughput for that task group
will not fluctuate as other workloads are added and removed on the system.
Cache use and bus bandwidth in a multi-workload environment can still
cause a performance deviation, but these are second order compared to
the cpu scheduling guarantees themselves.
Mike Waychison
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