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Community Blog Exploring Alibaba Group's PouchContainer Resource Management APIs – Part 1

Exploring Alibaba Group's PouchContainer Resource Management APIs – Part 1

In this article, we will introduce the common APIs of PouchContainer resource management and corresponding underlying kernel APIs.

PouchContainer is Alibaba Group's efficient, open source, enterprise-class container engine technology featuring strong isolation, high portability and low resource consumption. It can assist enterprise clients in containerizing inventory operations and improve the utilization of physical resources in ultra-large-scale data centers.

Resource management is an important part of the container runtime. This article will introduce you to the common APIs of PouchContainer resource management and corresponding underlying kernel APIs. This article provides test cases for some APIs for the sake of understandability.

Common APIs for PouchContainer Resource Management

API Description
--blkio-weight The relative weight of block device IO, which is an integer ranging from 0 to 100.
--blkio-weight-device IO relative weight of the specified block device.
--cpu-period Period value in the completely fair algorithm.
--cpu-quota Quota value in the completely fair algorithm.
--cpu-share CPU share (relative weight).
--cpuset-cpus Limits CPU cores used by the container.
--cpuset-mems Limits memory nodes used by the container, which only applies in NUMA systems.
--device-read-bps Limits read rate for the device, which is a positive integer measured in KB, MB, or GB.
--device-read-iops Limits read IO per second for the device, which is a positive integer.
--device-write-bps Limits write rate for the device, which is a positive integer measured in KB, MB, or GB.
--device-write-iops Limits write IO per second for the device, which is a positive integer.
-m, --memory Memory limit, which is a positive integer measured in B, KB, MB, or GB.
--memory-swap Total memory (physical memory + swap partition) limit, which is a positive integer measured in B, KB, MB, or GB.
--memory-swappiness The option to adjust the swap partition used by the container memory, which is an integer between 0 and 100 (inclusive).
--memory-wmark-ratio Used to calculate low_wmark, range of values: an integer between 0 and 100 (inclusive).
--oom-kill-disable Whether to kill the container when the memory is used up.
--oom-score-adj Sets the possibility that the container process will trigger OOM, the larger the value, the easier the OOM of the container process will be triggered.
--pids-limit Used to limit the number of PIDs inside the container.

Underlying Core Technology of PouchContainer Resource Management

Memory Resource Management

API Corresponding Kernel API Kernel API Description
-m, --memory cgroup/memory/memory.limit_in_bytes Sets the memory limit in bytes, and kb/KB, mb/MB or gb/GB can also be used.
--memory-swap cgroup/memory/memory.memsw.limit_in_bytes Sets the total memory and swap partition usage. By setting this value, you can prevent the process from using up the swap partition.
--memory-swappiness cgroup/memory/memory.swappiness Controls the tendency of the kernel to use the swap partition. Range of values: an integer between 0 and 100 (inclusive). The smaller the value, the more likely it is to use physical memory.
--memory-wmark-ratio cgroup/memory/memory.wmark_ratio Used to calculate low_wmark, low_wmark = memory.limit_in_bytes * MemoryWmarkRatio. When memory.usage_in_bytes is greater than low_wmark, the kernel thread is triggered to perform memory reclamation. When the memory.usage_in_bytes is less than high_wmark, the reclamation is stopped.
--oom-kill-disable cgroup/memory/memory.oom_control If it is set to 0, then when the memory usage exceeds the limit, the system will not kill the process, but block the process until memory is released for use. On the other hand, the system will send an event notification to the user mode, and the monitor of the user mode can respond according to the event, for example, increase the memory limit.
--oom-score-adj /proc/$pid/oom_score_adj Sets the possibility that the process will trigger OOM. The larger the value, the easier the OOM of the container process will be triggered.

CPU Resource Management

API Corresponding cgroup API Cgroup API Description
--cpu-period cgroup/cpu/cpu.cfs_period_us Used to limit CPU bandwidth, and needs to be used with cpu.cfs_quota_us. We can set the interval to 1 second and the quota to 0.5 seconds. The process in the cgroup can only run for a maximum of 0.5 seconds in 1 second, and then it will be forced to hibernate until the next 1 second.
--cpu-quota cgroup/cpu/cpu.cfs_quota_us Used to limit CPU bandwidth, and needs to be used with cpu.cfs_period_us.
--cpu-share cgroup/cpu/cpu.shares An API used to allocate the CPU proportion. Assuming that we create two cgroups (C1 and C2) in the root directory of cgroupfs, and configure cpu.shares to 512 and 1024 respectively. When there is a CPU contention between C1 and C2, C2 will get twice as much CPU usage as C1. It should be noted that CPU share will only work when they contend for CPU. If C2 is idle, then C1 can get the entire CPU resource.
--cpuset-cpus cgroup/cpuset/cpuset.cpus A list of CPUs that the process is allowed to use (for example: 0–4, 9).
--cpuset-mems cgroup/cpuset/cpuset.mems A list of memory nodes that the process is allowed to use (for example: 0–1).

IO Resource Management

API Corresponding cgroup API Cgroup API Description
--blkio-weight cgroup/blkio/blkio.weight Sets the weight value, which is an integer between 10 and 1,000 (inclusive). This is similar to cpu.shares, which allocates proportion instead of an absolute bandwidth limit, so it only works when different cgroups contend for the bandwidth of the same block device.
--blkio-weight-device cgroup/blkio/blkio.weight_device Sets the weight value for the specific device, which will override the above blkio.weight.
--device-read-bps cgroup/blkio/blkio.throttle.read_bps_device Sets the bandwidth limit for reading from the block device per second for a specific device.
--device-write-bps cgroup/blkio/blkio.throttle.write_bps_device Sets the bandwidth limit for writing to the block device per second. The device must be specified.
--device-read-iops cgroup/blkio/blkio.throttle.read_iops_device Sets the IO limit for reading from the block device. The device must be specified.
--device-write-iops cgroup/blkio/blkio.throttle.write_iops_device Sets the IO limit for writing to the block device. The device must be specified.

Other Resource Management APIs

API Corresponding cgroup API Cgroup API Description
--pids-limit cgroup/pids/pids.max Limits the number of processes.
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