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Memory Ballast

Status
Stability beta
Distributions core, contrib

Memory Ballast extension enables applications to configure memory ballast for the process. For more details see:

The following settings can be configured:

  • size_mib (default = 0, disabled): Is the memory ballast size, in MiB. Takes higher priority than size_in_percentage if both are specified at the same time.
  • size_in_percentage (default = 0, disabled): Set the memory ballast based on the total memory in percentage, value range is 1-100. It is supported in both containerized(eg, docker, k8s) and physical host environments.

How ballast size is calculated with percentage configuration When size_in_percentage is enabled with the value(1-100), the absolute ballast_size will be calculated by size_in_percentage * totalMemory / 100. The totalMemory can be retrieved for hosts and containers(in docker, k8s, etc) by the following steps,

  1. Look up Memory Cgroup subsystem on the target host or container, find out if there is any total memory limitation has been set for the running collector process. Check the value in memory.limit_in_bytes file under cgroup memory files (eg, /sys/fs/cgroup/memory/memory.limit_in_bytes).

  2. If memory.limit_in_bytes is positive value other than 9223372036854771712(0x7FFFFFFFFFFFF000). The ballast_size will be calculated by memory.limit_in_bytes * size_in_percentage / 100. If memory.limit_in_bytes value is 9223372036854771712(0x7FFFFFFFFFFFF000), it indicates there is no memory limit has been set for the collector process or the running container in cgroup. Then the totalMemory will be determined in next step.

  3. if there is no memory limit set in cgroup for the collector process or container where the collector is running. The total memory will be calculated by github.com/shirou/gopsutil/v3/mem[link] on mem.VirtualMemory().total which is supported in multiple OS systems.

Example: Config that uses 64 Mib of memory for the ballast:

extensions:
  memory_ballast:
    size_mib: 64

Config that uses 20% of the total memory for the ballast:

extensions:
  memory_ballast:
    size_in_percentage: 20