[RFC] qemu: set maxmem to host memory size

hypervisor.go

@@ -17,7 +17,10 @@
 package virtcontainers
 
 import (
+	"bufio"
 	"fmt"
+	"os"
+	"strconv"
 	"strings"
 )
 
@@ -32,6 +35,8 @@ const (
 	MockHypervisor HypervisorType = "mock"
 )
 
+const procMemInfo = "/proc/meminfo"
+
 const (
 	defaultVCPUs = 1
 	// 2 GiB
@@ -234,3 +239,36 @@ type hypervisor interface {
 	addDevice(devInfo interface{}, devType deviceType) error
 	getPodConsole(podID string) string
 }
+
+func getHostMemorySizeKb(memInfoPath string) (uint64, error) {
+	f, err := os.Open(memInfoPath)
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		// Expected format: ["MemTotal:", "1234", "kB"]
+		parts := strings.Fields(scanner.Text())
+
+		// Sanity checks: Skip malformed entries.
+		if len(parts) < 3 || parts[0] != "MemTotal:" || parts[2] != "kB" {
+			continue
+		}
+
+		sizeKb, err := strconv.ParseUint(parts[1], 0, 64)
+		if err != nil {
+			continue
+		}
+
+		return sizeKb, nil
+	}
+
+	// Handle errors that may have occurred during the reading of the file.
+	if err := scanner.Err(); err != nil {
+		return 0, err
+	}
+
+	return 0, fmt.Errorf("unable get MemTotal from %s", memInfoPath)
+}

hypervisor_test.go

@@ -18,6 +18,9 @@ package virtcontainers
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"reflect"
 	"testing"
 )
@@ -353,3 +356,62 @@ func TestAddKernelParamInvalid(t *testing.T) {
 		t.Fatal()
 	}
 }
+
+func TestGetHostMemorySizeKb(t *testing.T) {
+
+	type testData struct {
+		contents       string
+		expectedResult int
+		expectError    bool
+	}
+
+	data := []testData{
+		{
+			`
+			MemTotal:      1 kB
+			MemFree:       2 kB
+			SwapTotal:     3 kB
+			SwapFree:      4 kB
+			`,
+			1024,
+			false,
+		},
+		{
+			`
+			MemFree:       2 kB
+			SwapTotal:     3 kB
+			SwapFree:      4 kB
+			`,
+			0,
+			true,
+		},
+	}
+
+	dir, err := ioutil.TempDir("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	file := filepath.Join(dir, "meminfo")
+	if _, err := getHostMemorySizeKb(file); err == nil {
+		t.Fatalf("expected failure as file %q does not exist", file)
+	}
+
+	for _, d := range data {
+		if err := ioutil.WriteFile(file, []byte(d.contents), os.FileMode(0640)); err != nil {
+			t.Fatal(err)
+		}
+		defer os.Remove(file)
+
+		hostMemKb, err := getHostMemorySizeKb(file)
+
+		if (d.expectError && err == nil) || (!d.expectError && err != nil) {
+			t.Fatalf("got %d, input %v", hostMemKb, d)
+		}
+
+		if reflect.DeepEqual(hostMemKb, d.expectedResult) {
+			t.Fatalf("got %d, input %v", hostMemKb, d)
+		}
+	}
+}

qemu.go

@@ -106,6 +106,12 @@ const (
 	maxDevIDSize = 31
 )
 
+const (
+	// NVDIMM device needs memory space 1024MB
+	// See https://github.com/clearcontainers/runtime/issues/380
+	maxMemoryOffset = 1024
+)
+
 type qmpLogger struct{}
 
 func (l qmpLogger) V(level int32) bool {
@@ -468,13 +474,20 @@ func (q *qemu) setCPUResources(podConfig PodConfig) ciaoQemu.SMP {
 	return smp
 }
 
-func (q *qemu) setMemoryResources(podConfig PodConfig) ciaoQemu.Memory {
+func (q *qemu) setMemoryResources(podConfig PodConfig) (ciaoQemu.Memory, error) {
+	hostMemKb, err := getHostMemorySizeKb(procMemInfo)
+	if err != nil {
+		return ciaoQemu.Memory{}, fmt.Errorf("Unable to read memory info: %s", err)
+	}
+	if hostMemKb == 0 {
+		return ciaoQemu.Memory{}, fmt.Errorf("Error host memory size 0")
+	}
+
+	// add 1G memory space for nvdimm device (vm guest image)
+	memMax := fmt.Sprintf("%dM", int(float64(hostMemKb)/1024)+maxMemoryOffset)
 	mem := fmt.Sprintf("%dM", q.config.DefaultMemSz)
-	memMax := fmt.Sprintf("%dM", int(float64(q.config.DefaultMemSz)*1.5))
 	if podConfig.VMConfig.Memory > 0 {
 		mem = fmt.Sprintf("%dM", podConfig.VMConfig.Memory)
-		intMemMax := int(float64(podConfig.VMConfig.Memory) * 1.5)
-		memMax = fmt.Sprintf("%dM", intMemMax)
 	}
 
 	memory := ciaoQemu.Memory{
@@ -483,7 +496,7 @@ func (q *qemu) setMemoryResources(podConfig PodConfig) ciaoQemu.Memory {
 		MaxMem: memMax,
 	}
 
-	return memory
+	return memory, nil
 }
 
 // createPod is the Hypervisor pod creation implementation for ciaoQemu.
@@ -502,7 +515,10 @@ func (q *qemu) createPod(podConfig PodConfig) error {
 
 	smp := q.setCPUResources(podConfig)
 
-	memory := q.setMemoryResources(podConfig)
+	memory, err := q.setMemoryResources(podConfig)
+	if err != nil {
+		return err
+	}
 
 	knobs := ciaoQemu.Knobs{
 		NoUserConfig: true,

qemu_test.go

@@ -395,10 +395,16 @@ func TestQemuSetMemoryResources(t *testing.T) {
 
 	q := &qemu{}
 
+	hostMemKb, err := getHostMemorySizeKb(procMemInfo)
+	if err != nil {
+		t.Fatal(err)
+	}
+	memMax := fmt.Sprintf("%dM", int(float64(hostMemKb)/1024)+maxMemoryOffset)
+
 	expectedOut := ciaoQemu.Memory{
 		Size:   "1000M",
 		Slots:  uint8(2),
-		MaxMem: "1500M",
+		MaxMem: memMax,
 	}
 
 	vmConfig := Resources{
@@ -409,7 +415,10 @@ func TestQemuSetMemoryResources(t *testing.T) {
 		VMConfig: vmConfig,
 	}
 
-	memory := q.setMemoryResources(podConfig)
+	memory, err := q.setMemoryResources(podConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	if reflect.DeepEqual(memory, expectedOut) == false {
 		t.Fatalf("Got %v\nExpecting %v", memory, expectedOut)