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414642efdb
Move the options for the podman build doc to a common md that can be used by both podman build and podman farm build. Signed-off-by: Urvashi Mohnani <umohnani@redhat.com>
46 lines
2.2 KiB
Markdown
46 lines
2.2 KiB
Markdown
####> This option file is used in:
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####> podman build, container clone, create, farm build, pod clone, pod create, run, update
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####> If file is edited, make sure the changes
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####> are applicable to all of those.
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#### **--cpu-shares**, **-c**=*shares*
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CPU shares (relative weight).
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By default, all containers get the same proportion of CPU cycles. This
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proportion can be modified by changing the container's CPU share weighting
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relative to the combined weight of all the running containers.
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Default weight is **1024**.
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The proportion only applies when CPU-intensive processes are running.
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When tasks in one container are idle, other containers can use the
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left-over CPU time. The actual amount of CPU time varies depending on
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the number of containers running on the system.
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For example, consider three containers, one has a cpu-share of 1024 and
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two others have a cpu-share setting of 512. When processes in all three
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containers attempt to use 100% of CPU, the first container receives
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50% of the total CPU time. If a fourth container is added with a cpu-share
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of 1024, the first container only gets 33% of the CPU. The remaining containers
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receive 16.5%, 16.5% and 33% of the CPU.
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On a multi-core system, the shares of CPU time are distributed over all CPU
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cores. Even if a container is limited to less than 100% of CPU time, it can
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use 100% of each individual CPU core.
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For example, consider a system with more than three cores.
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If the container _C0_ is started with **--cpu-shares=512** running one process,
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and another container _C1_ with **--cpu-shares=1024** running two processes,
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this can result in the following division of CPU shares:
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| PID | container | CPU | CPU share |
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| ---- | ----------- | ------- | ------------ |
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| 100 | C0 | 0 | 100% of CPU0 |
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| 101 | C1 | 1 | 100% of CPU1 |
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| 102 | C1 | 2 | 100% of CPU2 |
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On some systems, changing the resource limits may not be allowed for non-root
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users. For more details, see
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https://github.com/containers/podman/blob/main/troubleshooting.md#26-running-containers-with-resource-limits-fails-with-a-permissions-error
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This option is not supported on cgroups V1 rootless systems.
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