Implemented linux ionice funtionality

ionice_linux.go

@@ -0,0 +1,80 @@
+//go:build linux
+// +build linux
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"syscall"
+
+	proc "github.com/shirou/gopsutil/v3/process"
+)
+
+// GetIOPriority достаёт приоритет вводв-вывода для укаанного процесса.
+func GetIOPriority(which int, who int) (uint32, error) {
+	var (
+		err       error
+		r0, _, e1 = syscall.Syscall(syscall.SYS_IOPRIO_GET, uintptr(which), uintptr(who), 0)
+		prio      = uint32(r0)
+	)
+
+	if e1 != 0 {
+		err = fmt.Errorf(fmt.Sprintf("Received error number %v", e1))
+	}
+
+	return prio, err
+}
+
+// GetIOPriority ставит приоритет вводв-вывода для укаанного процесса.
+func SetIOPriority(which int, who int, prio uint32) error {
+	var (
+		err      error
+		_, _, e1 = syscall.Syscall(syscall.SYS_IOPRIO_SET, uintptr(which), uintptr(who), uintptr(prio))
+	)
+
+	if e1 != 0 {
+		err = fmt.Errorf(fmt.Sprintf("Received error number %v", e1))
+	}
+
+	return err
+}
+
+// IORenice выставляет процессу приоритет для операций ввода-вывода.
+func IORenice(cnf Config, p *proc.Process, processName string) {
+	if currentIOPrioLevel, err := GetIOPriority(IOPRIO_WHO_PROCESS, int(p.Pid)); err == nil {
+		currentClass, currentClassdata := PrioToClassAndClassdata(currentIOPrioLevel)
+		class := ioreniceClass[processName]
+		classdata := ioreniceClassdata[processName]
+
+		if class == currentClass && classdata == currentClassdata {
+			if cnf.Debug && currentIOPrioLevel != 0 { // 0 - это дефолтный уровень io niceness.
+				log.Printf(
+					"IONiceness for %s(%d) already set to %d %d",
+					processName,
+					p.Pid,
+					currentClass,
+					currentClassdata,
+				)
+			}
+		} else {
+			iopriority := ClassAndClassdataToPrio(class, classdata)
+
+			_ = SetIOPriority(IOPRIO_WHO_PROCESS, int(p.Pid), iopriority)
+
+			if cnf.Debug {
+				log.Printf(
+					"Set ioniceness for %s(%d) to %d %d (was %d %d)",
+					processName,
+					p.Pid,
+					class,
+					classdata,
+					currentClass,
+					currentClassdata,
+				)
+			}
+		}
+	} else {
+		log.Printf("Unable to get ioprio for %s(%d)", processName, p.Pid)
+	}
+}