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Implement systemd support for freezer

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These PR does a few things.  It ensures that the freezer cgroup is
joined in the systemd driver.  It also provides a public api for setting
the freezer state via the cgroups package.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
This commit is contained in:
Michael Crosby 2014-05-30 15:09:07 -07:00
parent cfde39c592
commit 2616e87cad
5 changed files with 118 additions and 68 deletions
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11
libcontainer/cgroups/cgroups.go
View file

@ -10,6 +10,14 @@ var (
ErrNotFound = errors.New("mountpoint not found")
)
type FreezerState string
const (
Undefined FreezerState = ""
Frozen FreezerState = "FROZEN"
Thawed FreezerState = "THAWED"
)
type Cgroup struct {
Name string `json:"name,omitempty"`
Parent string `json:"parent,omitempty"` // name of parent cgroup or slice
@ -23,8 +31,7 @@ type Cgroup struct {
CpuQuota int64 `json:"cpu_quota,omitempty"` // CPU hardcap limit (in usecs). Allowed cpu time in a given period.
CpuPeriod int64 `json:"cpu_period,omitempty"` // CPU period to be used for hardcapping (in usecs). 0 to use system default.
CpusetCpus string `json:"cpuset_cpus,omitempty"` // CPU to use
Freezer string `json:"freezer,omitempty"` // set the freeze value for the process
Freezer FreezerState `json:"freezer,omitempty"` // set the freeze value for the process
Slice string `json:"slice,omitempty"` // Parent slice to use for systemd
}

103
libcontainer/cgroups/fs/apply_raw.go
View file

@ -37,65 +37,28 @@ type data struct {
}
func Apply(c *cgroups.Cgroup, pid int) (cgroups.ActiveCgroup, error) {
// We have two implementation of cgroups support, one is based on
// systemd and the dbus api, and one is based on raw cgroup fs operations
// following the pre-single-writer model docs at:
// http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups/
//
// we can pick any subsystem to find the root
cgroupRoot, err := cgroups.FindCgroupMountpoint("cpu")
d, err := getCgroupData(c, pid)
if err != nil {
return nil, err
}
cgroupRoot = filepath.Dir(cgroupRoot)
if _, err := os.Stat(cgroupRoot); err != nil {
return nil, fmt.Errorf("cgroups fs not found")
}
cgroup := c.Name
if c.Parent != "" {
cgroup = filepath.Join(c.Parent, cgroup)
}
d := &data{
root: cgroupRoot,
cgroup: cgroup,
c: c,
pid: pid,
}
for _, sys := range subsystems {
if err := sys.Set(d); err != nil {
d.Cleanup()
return nil, err
}
}
return d, nil
}
func GetStats(c *cgroups.Cgroup) (*cgroups.Stats, error) {
stats := cgroups.NewStats()
cgroupRoot, err := cgroups.FindCgroupMountpoint("cpu")
d, err := getCgroupData(c, 0)
if err != nil {
return nil, err
}
cgroupRoot = filepath.Dir(cgroupRoot)
if _, err := os.Stat(cgroupRoot); err != nil {
return nil, fmt.Errorf("cgroups fs not found")
}
cgroup := c.Name
if c.Parent != "" {
cgroup = filepath.Join(c.Parent, cgroup)
}
d := &data{
root: cgroupRoot,
cgroup: cgroup,
c: c,
}
for _, sys := range subsystems {
if err := sys.GetStats(d, stats); err != nil {
@ -106,27 +69,26 @@ func GetStats(c *cgroups.Cgroup) (*cgroups.Stats, error) {
return stats, nil
}
// Freeze toggles the container's freezer cgroup depending on the state
// provided
func Freeze(c *cgroups.Cgroup, state cgroups.FreezerState) error {
d, err := getCgroupData(c, 0)
if err != nil {
return err
}
c.Freezer = state
freezer := subsystems["freezer"]
return freezer.Set(d)
}
func GetPids(c *cgroups.Cgroup) ([]int, error) {
cgroupRoot, err := cgroups.FindCgroupMountpoint("cpu")
d, err := getCgroupData(c, 0)
if err != nil {
return nil, err
}
cgroupRoot = filepath.Dir(cgroupRoot)
if _, err := os.Stat(cgroupRoot); err != nil {
return nil, fmt.Errorf("cgroup root %s not found", cgroupRoot)
}
cgroup := c.Name
if c.Parent != "" {
cgroup = filepath.Join(c.Parent, cgroup)
}
d := &data{
root: cgroupRoot,
cgroup: cgroup,
c: c,
}
dir, err := d.path("devices")
if err != nil {
@ -136,6 +98,31 @@ func GetPids(c *cgroups.Cgroup) ([]int, error) {
return cgroups.ReadProcsFile(dir)
}
func getCgroupData(c *cgroups.Cgroup, pid int) (*data, error) {
// we can pick any subsystem to find the root
cgroupRoot, err := cgroups.FindCgroupMountpoint("cpu")
if err != nil {
return nil, err
}
cgroupRoot = filepath.Dir(cgroupRoot)
if _, err := os.Stat(cgroupRoot); err != nil {
return nil, fmt.Errorf("cgroups fs not found")
}
cgroup := c.Name
if c.Parent != "" {
cgroup = filepath.Join(c.Parent, cgroup)
}
return &data{
root: cgroupRoot,
cgroup: cgroup,
c: c,
pid: pid,
}, nil
}
func (raw *data) parent(subsystem string) (string, error) {
initPath, err := cgroups.GetInitCgroupDir(subsystem)
if err != nil {

5
libcontainer/cgroups/fs/freezer.go
View file

@ -20,11 +20,12 @@ func (s *freezerGroup) Set(d *data) error {
return nil
}
if d.c.Freezer != "" {
if err := writeFile(dir, "freezer.state", d.c.Freezer); err != nil {
if d.c.Freezer != cgroups.Undefined {
if err := writeFile(dir, "freezer.state", string(d.c.Freezer)); err != nil {
return err
}
}
return nil
}

4
libcontainer/cgroups/systemd/apply_nosystemd.go
View file

@ -19,3 +19,7 @@ func Apply(c *cgroups.Cgroup, pid int) (cgroups.ActiveCgroup, error) {
func GetPids(c *cgroups.Cgroup) ([]int, error) {
return nil, fmt.Errorf("Systemd not supported")
}
func Freeze(c *cgroups.Cgroup, state cgroups.FreezerState) error {
return fmt.Errorf("Systemd not supported")
}

61
libcontainer/cgroups/systemd/apply_systemd.go
View file

@ -218,6 +218,14 @@ func Apply(c *cgroups.Cgroup, pid int) (cgroups.ActiveCgroup, error) {
}
}
// we need to manually join the freezer cgroup in systemd because it does not currently support it
// via the dbus api
freezerPath, err := joinFreezer(c, pid)
if err != nil {
return nil, err
}
res.cleanupDirs = append(res.cleanupDirs, freezerPath)
if len(cpusetArgs) != 0 {
// systemd does not atm set up the cpuset controller, so we must manually
// join it. Additionally that is a very finicky controller where each
@ -227,14 +235,19 @@ func Apply(c *cgroups.Cgroup, pid int) (cgroups.ActiveCgroup, error) {
if err != nil {
return nil, err
}
initPath, err := cgroups.GetInitCgroupDir("cpuset")
if err != nil {
return nil, err
}
rootPath := filepath.Join(mountpoint, initPath)
var (
foundCpus bool
foundMems bool
path := filepath.Join(mountpoint, initPath, c.Parent+"-"+c.Name)
rootPath = filepath.Join(mountpoint, initPath)
path = filepath.Join(mountpoint, initPath, c.Parent+"-"+c.Name)
)
res.cleanupDirs = append(res.cleanupDirs, path)
@ -242,9 +255,6 @@ func Apply(c *cgroups.Cgroup, pid int) (cgroups.ActiveCgroup, error) {
return nil, err
}
foundCpus := false
foundMems := false
for _, arg := range cpusetArgs {
if arg.File == "cpuset.cpus" {
foundCpus = true
@ -303,6 +313,47 @@ func (c *systemdCgroup) Cleanup() error {
return nil
}
func joinFreezer(c *cgroups.Cgroup, pid int) (string, error) {
path, err := getFreezerPath(c)
if err != nil {
return "", err
}
if err := os.MkdirAll(path, 0755); err != nil && !os.IsExist(err) {
return "", err
}
if err := ioutil.WriteFile(filepath.Join(path, "cgroup.procs"), []byte(strconv.Itoa(pid)), 0700); err != nil {
return "", err
}
return path, nil
}
func getFreezerPath(c *cgroups.Cgroup) (string, error) {
mountpoint, err := cgroups.FindCgroupMountpoint("freezer")
if err != nil {
return "", err
}
initPath, err := cgroups.GetInitCgroupDir("freezer")
if err != nil {
return "", err
}
return filepath.Join(mountpoint, initPath, fmt.Sprintf("%s-%s", c.Parent, c.Name)), nil
}
func Freeze(c *cgroups.Cgroup, state cgroups.FreezerState) error {
path, err := getFreezerPath(c)
if err != nil {
return err
}
return ioutil.WriteFile(filepath.Join(path, "freezer.state"), []byte(state), 0)
}
func GetPids(c *cgroups.Cgroup) ([]int, error) {
unitName := getUnitName(c)