Menu
Docker v1.12 service comes with four flags for setting the resource limits on a service.
--limit-cpu value Limit CPUs (default 0.000)
--limit-memory value Limit Memory (default 0 B)
--reserve-cpu value Reserve CPUs (default 0.000)
--reserve-memory value Reserve Memory (default 0 B)
What is the difference between limit and reserve in this context?
What does the cpu value mean in here? Does this mean number of cores? cpu share? What is the unit?
418
Limit Docker Container CPU Usage Just like RAM usage, Docker containers don't have any default limitations for the host's CPU. Giving containers unlimited CPU usage can lead to issues. There are several ways to define how much CPU resources from the host machine you want to assign to containers.
--memory-reservation. Allows you to specify a soft limit smaller than --memory which is activated when Docker detects contention or low memory on the host machine. If you use --memory-reservation , it must be set lower than --memory for it to take precedence.
Answer : A resource limit is hard limit for your service, while a reservation is used to find a host with adequate resources for scheduling.
As others have said, you cannot reserve memory for processes, and therefore containers. However, you could have the node app called from a script that will check the available memory and exit if it is below a certain threshold.
Reserve holds those resources on the host so they are always available for the container. Think dedicated resources.
Limit prevents the binary inside the container from using more than that. Think of controlling runaway processes in container.
Based on my limited testing with stress, --limit-cpu is percent of a core, though if there are multiple threads, it'll spread those out across core's and seems to attempt to keep the total near what you'd expect.
In the below pic, from left to right, was --limit-cpu 4, then 2.5, then 2, then 1. All of those tests had stress set to CPU of 4 (worker threads).
136
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
