08c7075c40
Kernel memory is not allowed to be updated if container is running, it's not actually a precise kernel limitation. Before kernel version 4.6, kernel memory will not be accounted until kernel memory limit is set, if a container created with kernel memory initialized, kernel memory is accounted as soon as process created in container, so kernel memory limit update is allowed afterward. If kernel memory is not initialized, kernel memory consumed by processes in container will not be accounted, so we can't update the limit because the account will be wrong. So update kernel memory of a running container with kernel memory initialized is allowed, we should soften the limitation by docker. Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
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update
Usage: docker update [OPTIONS] CONTAINER [CONTAINER...]
Update configuration of one or more containers
Options:
--blkio-weight value Block IO (relative weight), between 10 and 1000
--cpu-period int Limit CPU CFS (Completely Fair Scheduler) period
--cpu-quota int Limit CPU CFS (Completely Fair Scheduler) quota
-c, --cpu-shares int CPU shares (relative weight)
--cpuset-cpus string CPUs in which to allow execution (0-3, 0,1)
--cpuset-mems string MEMs in which to allow execution (0-3, 0,1)
--help Print usage
--kernel-memory string Kernel memory limit
-m, --memory string Memory limit
--memory-reservation string Memory soft limit
--memory-swap string Swap limit equal to memory plus swap: '-1' to enable unlimited swap
--restart string Restart policy to apply when a container exits
The docker update command dynamically updates container configuration.
You can use this command to prevent containers from consuming too many resources
from their Docker host. With a single command, you can place limits on
a single container or on many. To specify more than one container, provide
space-separated list of container names or IDs.
With the exception of the --kernel-memory value, you can specify these
options on a running or a stopped container. You can only update
--kernel-memory on a stopped container or on a running container with
kernel memory initialized. For example, if you started a container with
command:
# docker run -ti --name test --kernel-memory 50M ubuntu bash
You can update kernel memory of this running container:
# docker update --kernel-memory 80M test
If you started a container without kernel memory initialized:
# docker run -ti --name test2 --memory 300M ubuntu bash
Update kernel memory of running container test2 will fail, you can only
stop the container and update kernel memory then. The next time you
restart it, the container uses the new value.
Another configuration you can change with this command is restart policy,
new restart policy will take effect instantly after you run docker update
on a container.
EXAMPLES
The following sections illustrate ways to use this command.
Update a container with cpu-shares=512
To limit a container's cpu-shares to 512, first identify the container name or ID. You can use docker ps to find these values. You can also use the ID returned from the docker run command. Then, do the following:
$ docker update --cpu-shares 512 abebf7571666
Update a container with cpu-shares and memory
To update multiple resource configurations for multiple containers:
$ docker update --cpu-shares 512 -m 300M abebf7571666 hopeful_morse
Update a container's restart policy
To update restart policy for one or more containers:
$ docker update --restart=on-failure:3 abebf7571666 hopeful_morse