syncthing/lib/osutil/lowprio_unix.go

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// Copyright (C) 2018 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
//go:build (!windows && !linux) || android
// +build !windows,!linux android
package osutil
import (
"fmt"
"syscall"
)
// SetLowPriority lowers the process CPU scheduling priority, and possibly
// I/O priority depending on the platform and OS.
func SetLowPriority() error {
// Process zero is "self", niceness value 9 is something between 0
// (default) and 19 (worst priority).
const (
pidSelf = 0
wantNiceLevel = 9
)
if cur, err := syscall.Getpriority(syscall.PRIO_PROCESS, pidSelf); err == nil && cur >= wantNiceLevel {
// We're done here.
return nil
}
if err := syscall.Setpriority(syscall.PRIO_PROCESS, pidSelf, wantNiceLevel); err != nil {
return fmt.Errorf("set niceness: %w", err)
}
return nil
}