Merge pull request opencontainers#1191 from utam0k/io-prio

Add I/O Priority Configuration for process group in Linux Containers

Author: AkihiroSuda

config.md

@@ -320,6 +320,12 @@ For Linux-based systems, the `process` object supports the following process-spe
     * **`period`** (uint64, OPTIONAL) represents the length of the period in nanoseconds used for determining the process runtime, used by the deadline scheduler. If not set, the runtime must use the value 0.
 * **`selinuxLabel`** (string, OPTIONAL) specifies the SELinux label for the process.
     For more information about SELinux, see  [SELinux documentation][selinux].
+* **`ioPriority`** (object, OPTIONAL) configures the I/O priority settings for the container's processes within the process group.
+    The I/O priority settings will be automatically applied to the entire process group, affecting all processes within the container.
+    The following properties are available:
+
+    * **`class`** (string, REQUIRED) specifies the I/O scheduling class. Possible values are `IOPRIO_CLASS_RT`, `IOPRIO_CLASS_BE`, and `IOPRIO_CLASS_IDLE`.
+    * **`priority`** (int, REQUIRED) specifies the priority level within the class. The value should be an integer ranging from 0 (highest) to 7 (lowest).
 
 ### <a name="configUser" />User
 
@@ -361,6 +367,10 @@ _Note: symbolic name for uid and gid, such as uname and gname respectively, are
     ],
     "apparmorProfile": "acme_secure_profile",
     "selinuxLabel": "system_u:system_r:svirt_lxc_net_t:s0:c124,c675",
+    "ioPriority": {
+        "class": "IOPRIO_CLASS_IDLE",
+        "priority": 4
+    },
     "noNewPrivileges": true,
     "capabilities": {
         "bounding": [
@@ -761,6 +771,10 @@ Here is a full example `config.json` for reference.
         "apparmorProfile": "acme_secure_profile",
         "oomScoreAdj": 100,
         "selinuxLabel": "system_u:system_r:svirt_lxc_net_t:s0:c124,c675",
+        "ioPriority": {
+            "class": "IOPRIO_CLASS_IDLE",
+            "priority": 4
+        },
         "noNewPrivileges": true
     },
     "root": {

schema/config-schema.json

@@ -144,6 +144,15 @@
                 "selinuxLabel": {
                     "type": "string"
                 },
+                "ioPriority": {
+                    "class": "string",
+                    "enum": [
+                        "IOPRIO_CLASS_RT",
+                        "IOPRIO_CLASS_BE",
+                        "IOPRIO_CLASS_IDLE"
+                    ],
+                    "priority": "integer"
+                },
                 "noNewPrivileges": {
                     "type": "boolean"
                 },

specs-go/config.go

@@ -92,6 +92,8 @@ type Process struct {
 	Scheduler *Scheduler `json:"scheduler,omitempty" platform:"linux"`
 	// SelinuxLabel specifies the selinux context that the container process is run as.
 	SelinuxLabel string `json:"selinuxLabel,omitempty" platform:"linux"`
+	// IOPriority contains the I/O priority settings for the cgroup.
+	IOPriority *LinuxIOPriority `json:"ioPriority,omitempty" platform:"linux"`
 }
 
 // LinuxCapabilities specifies the list of allowed capabilities that are kept for a process.
@@ -109,6 +111,22 @@ type LinuxCapabilities struct {
 	Ambient []string `json:"ambient,omitempty" platform:"linux"`
 }
 
+// IOPriority represents I/O priority settings for the container's processes within the process group.
+type LinuxIOPriority struct {
+	Class    IOPriorityClass `json:"class"`
+	Priority int             `json:"priority"`
+}
+
+// IOPriorityClass represents an I/O scheduling class.
+type IOPriorityClass string
+
+// Possible values for IOPriorityClass.
+const (
+	IOPRIO_CLASS_RT   IOPriorityClass = "IOPRIO_CLASS_RT"
+	IOPRIO_CLASS_BE   IOPriorityClass = "IOPRIO_CLASS_BE"
+	IOPRIO_CLASS_IDLE IOPriorityClass = "IOPRIO_CLASS_IDLE"
+)
+
 // Box specifies dimensions of a rectangle. Used for specifying the size of a console.
 type Box struct {
 	// Height is the vertical dimension of a box.