daemon: don't adjust oom-score if score is 0

thaJeztah · thaJeztah · commit cf7a5be0f2ee · 2020-10-05T19:52:02.000+02:00
This patch makes two changes if --oom-score-adj is set to 0

- do not adjust the oom-score-adjust cgroup for dockerd
- do not set the hard-coded -999 score for containerd if
  containerd is running as child process

Before this change:

oom-score-adj | dockerd       | containerd as child-process
--------------|---------------|----------------------------
-             | -500          | -500 (same as dockerd)
-100          | -100          | -100 (same as dockerd)
 0            |  0            | -999 (hard-coded default)

With this change:

oom-score-adj | dockerd       | containerd as child-process
--------------|---------------|----------------------------
-             | -500          | -500 (same as dockerd)
-100          | -100          | -100 (same as dockerd)
0             | not adjusted  | not adjusted

Signed-off-by: Sebastiaan van Stijn &lt;github@gone.nl&gt;
diff --git a/daemon/daemon_unix.go b/daemon/daemon_unix.go
@@ -1636,6 +1636,9 @@ func setMayDetachMounts() error {
 }
 
 func setupOOMScoreAdj(score int) error {
+	if score == 0 {
+		return nil
+	}
 	f, err := os.OpenFile("/proc/self/oom_score_adj", os.O_WRONLY, 0)
 	if err != nil {
 		return err
diff --git a/libcontainerd/supervisor/remote_daemon_linux.go b/libcontainerd/supervisor/remote_daemon_linux.go
@@ -28,9 +28,6 @@ func (r *remote) setDefaults() {
 	if r.Debug.Address == "" {
 		r.Debug.Address = filepath.Join(r.stateDir, debugSockFile)
 	}
-	if r.OOMScore == 0 {
-		r.OOMScore = -999
-	}
 
 	for key, conf := range r.pluginConfs.Plugins {
 		if conf == nil {

Original file line number	Diff line number	Diff line change
`@@ -1636,6 +1636,9 @@ func setMayDetachMounts() error {`
`1636`	`1636`	`}`
`1637`	`1637`
`1638`	`1638`	`func setupOOMScoreAdj(score int) error {`
	`1639`	`+ if score == 0 {`
	`1640`	`+ return nil`
	`1641`	`+ }`
`1639`	`1642`	`f, err := os.OpenFile("/proc/self/oom_score_adj", os.O_WRONLY, 0)`
`1640`	`1643`	`if err != nil {`
`1641`	`1644`	`return err`
Original file line number	Diff line number	Diff line change
`@@ -28,9 +28,6 @@ func (r *remote) setDefaults() {`
`28`	`28`	`if r.Debug.Address == "" {`
`29`	`29`	`r.Debug.Address = filepath.Join(r.stateDir, debugSockFile)`
`30`	`30`	`}`
`31`		`- if r.OOMScore == 0 {`
`32`		`- r.OOMScore = -999`
`33`		`- }`
`34`	`31`
`35`	`32`	`for key, conf := range r.pluginConfs.Plugins {`
`36`	`33`	`if conf == nil {`