Alibaba Cloud Linux:Enable CPU Burst on the cgroup v1 interface

Enable CPU Burst

1. Check whether the CPU Burst global switch is enabled.

   cat /proc/sys/kernel/sched_cfs_bw_burst_enabled

   Output:

   • 1: The global switch is enabled.

     Note

     The global switch is enabled by default.

   • Other value: The global switch is disabled.

     To enable it, run:

     sudo sh -c 'echo 1 > /proc/sys/kernel/sched_cfs_bw_burst_enabled'

2. Enable CPU Burst in a specific child cgroup.

   Note

   CPU Burst is disabled in all child cgroups by default.

   1. Go to the child cgroup directory and check whether Completely Fair Scheduler (CFS) Bandwidth Controller throttling is active.

      Replace <cgroup> with your child cgroup name.

      cd /sys/fs/cgroup/cpu/<cgroup>/
      cat cpu.cfs_period_us
      cat cpu.cfs_quota_us

      A positive return value means CFS Bandwidth Controller throttling is active. With CPU Burst enabled, the container can exceed its CPU limit.

   2. Check the current default CPU Burst setting.

      cat cpu.cfs_burst_us

      The default value 0 means CPU Burst is disabled.

   3. Set a value for cpu.cfs_burst_us to enable CPU Burst.

      Set this parameter to a positive integer that specifies the maximum extra CPU resources the child cgroup can use in bursts. Example:

      1. Set cpu.cfs_quota_us and cpu.cfs_period_us for the CFS Bandwidth Controller.

         This sets cpu.cfs_period_us to 100 ms and cpu.cfs_quota_us to 400 ms, giving the child cgroup a steady 4-CPU allocation (cpu.cfs_quota_us / cpu.cfs_period_us).

         sudo sh -c 'echo 400000 > cpu.cfs_quota_us'
         sudo sh -c 'echo 100000 > cpu.cfs_period_us'

      2. Set cpu.cfs_burst_us to enable CPU Burst.

         This sets cpu.cfs_burst_us to 600 ms, allowing the child cgroup to burst up to 6 additional CPUs (cpu.cfs_burst_us / cpu.cfs_period_us).

         sudo sh -c 'echo 600000 > cpu.cfs_burst_us'

Query CPU Burst statistics

Go to the target child cgroup directory and view its statistics.

Replace <cgroup> with your child cgroup name.

cd /sys/fs/cgroup/cpu/<cgroup>/
cat cpu.stat

Key output fields:

• nr_burst: Number of CPU Burst triggers.

• burst_time: Total time the child cgroup used extra CPU resources in bursts.