CGroupStatus QML Type

Provides information on the status of a Linux cgroup. More...

• List of all members, including inherited members

Properties

• cpuLoad : real
• cpuPSI : PressureStallInformation
• ioPSI : PressureStallInformation
• max : int
• memoryHigh : int
• memoryMax : int
• memoryPSI : PressureStallInformation
• memoryUsed : int
• path : string
• roleNames : list<string>

Methods

• void update()

Detailed Description

CGroupStatus monitors a Linux cgroup v2 control group, providing both memory statistics and pressure stall information (PSI). It defaults to the cgroup of the current process, but you can point it at any other cgroup by setting the path property.

If you need system-wide instead of per-cgroup information, see SystemStatus.

Memory and CPU monitoring

The memoryHigh and memoryMax limits are read once when path is set. The current memory usage is available via memoryUsed, which is updated on every call to update().

Similarly, cpuLoad is also updated on every call to update(), and reflects the CPU utilization of the cgroup since the previous update() call.

You can use this type as a MonitorModel data source to record memory usage over time:

import QtQuick
import QtApplicationManager

MonitorModel {
    CGroupStatus {}
}

Alternatively, drive updates yourself with a Timer:

import QtQuick
import QtApplicationManager

CGroupStatus { id: cgroupStatus }

Timer {
    interval: 1000
    running: true
    repeat: true
    onTriggered: cgroupStatus.update()
}

Pressure stall monitoring

The cpuPSI, memoryPSI, and ioPSI properties each expose a PressureStallInformation object for event-driven pressure monitoring. Configure the desired mode, timeWindow, and stallTime, then connect to the triggered signal to react when the threshold is exceeded:

import QtQuick
import QtApplicationManager

CGroupStatus {
    id: cgroupStatus

    Component.onCompleted: {
        memoryPSI.timeWindow = 2000  // 2 second observation window
        memoryPSI.stallTime = 100    // fire if stalled for 100ms within that window
        memoryPSI.mode = PressureStallInformation.Some
    }
}

Connections {
    target: cgroupStatus.memoryPSI
    function onTriggered() { console.log("Memory pressure detected") }
}

See also MemoryStatus, MonitorModel, PressureStallInformation, and SystemStatus.

Property Documentation

cpuLoad : real [read-only]

The average CPU utilization of this cgroup over the interval between the two most recent calls to update() (or between path being set and the first update() call), as a value ranging from 0 (inclusive, completely idle) to 1 (inclusive, all CPU cores fully busy).

The value is computed from the cgroup's cpu.stat usage_usec counter, divided by elapsed wall-clock time and normalized by the number of CPU cores on the system.

Returns 0 if not running under cgroup v2 or if the CPU controller is not enabled for this cgroup.

See also update().

cpuPSI : PressureStallInformation [read-only]

Provides access to CPU pressure stall monitoring for this cgroup. Monitors situations where tasks are delayed waiting for CPU time.

Only functional when running under cgroup v2.

See also PressureStallInformation, memoryPSI, and ioPSI.

ioPSI : PressureStallInformation [read-only]

Provides access to I/O pressure stall monitoring for this cgroup. Monitors situations where tasks are delayed waiting for I/O operations to complete.

Only functional when running under cgroup v2.

See also PressureStallInformation, cpuPSI, and memoryPSI.

max : int [read-only]

This property always returns the largest unsigned 64-bit integer value, which is used to express the max value in cgroup v2 files.

memoryHigh : int [read-only]

The memory.high soft limit (in bytes) of this cgroup, or 0 if not running under cgroup v2. When the cgroup file contains the string "max", this returns max.

memoryMax : int [read-only]

The memory.max hard limit (in bytes) of this cgroup, or 0 if not running under cgroup v2. When the cgroup file contains the string "max", this returns max.

memoryPSI : PressureStallInformation [read-only]

Provides access to memory pressure stall monitoring for this cgroup. Monitors situations where tasks are delayed waiting for memory to become available.

Only functional when running under cgroup v2.

See also PressureStallInformation, cpuPSI, and ioPSI.

memoryUsed : int [read-only]

The current memory usage (in bytes) of this cgroup, as reported by memory.current. Updated on every call to update(). Returns 0 if not running under cgroup v2.

See also update().

path : string

The path of the cgroup this CGroupStatus instance is monitoring. This is only relevant on Linux systems when running cgroup v2, and will be an empty string otherwise.

This defaults to the cgroup of the current process, but you can set it to another cgroup valid cgroup identifier (eg: user.slice/user-1000.slice/session-2.scope).

roleNames : list<string> [read-only]

Names of the roles provided by CGroupStatus when used as a MonitorModel data source.

See also MonitorModel.

Method Documentation

void update()

Updates the memoryUsed and cpuLoad properties.

See also memoryUsed and cpuLoad.