Service memory accounting (cgroup v2)

Live RSS vs hard limit for a systemd service; current near max = imminent OOM

cat /sys/fs/cgroup/system.slice/<name>.service/memory.current /sys/fs/cgroup/system.slice/<name>.service/memory.max
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cgroups8 commands
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cgroupsmemoryperformancetroubleshooting

More cgroups commands

  • Memory PSI pressure stall
    cat /sys/fs/cgroup/system.slice/<name>.service/memory.pressure

    PSI: time tasks stalled on memory reclaim; rising avg10 = thrashing before OOM

  • CPU throttling stats (cgroup v2)
    grep -E 'nr_throttled|throttled_usec' /sys/fs/cgroup/system.slice/<name>.service/cpu.stat

    Count and total usec a cgroup was CPU-throttled by cpu.max quota

  • Read and set CPU quota (cgroup v2)
    cat /sys/fs/cgroup/system.slice/<name>.service/cpu.max # "max 100000" = unlimited; "50000 100000" = 0.5 core

    cpu.max is 'quota period' in usec; 'max' = no limit. note: prefer systemctl set-property

  • Per-device IO pressure and stats
    cat /sys/fs/cgroup/system.slice/<name>.service/io.pressure /sys/fs/cgroup/system.slice/<name>.service/io.stat

    PSI io stall plus per-major:minor rbytes/wbytes/rios; pin noisy disk neighbors

  • List PIDs in a service cgroup
    cat /sys/fs/cgroup/system.slice/<name>.service/cgroup.procs; systemctl status <name>.service | grep CGroup

    Every PID currently in the service slice; cross-check with systemctl status tree

all 8 cgroups commands