Use GlobalMemoryStatusEx to get total physical memory on Windows node

pkg/kubelet/winstats/perfcounter_nodestats.go

@@ -23,18 +23,32 @@ import (
 	"os"
 	"runtime"
 	"sync"
-	"syscall"
 	"time"
 	"unsafe"
 
 	"github.com/golang/glog"
 	cadvisorapi "github.com/google/cadvisor/info/v1"
+	"golang.org/x/sys/windows"
 	"k8s.io/apimachinery/pkg/util/wait"
 )
 
+// MemoryStatusEx is the same as Windows structure MEMORYSTATUSEX
+// https://msdn.microsoft.com/en-us/library/windows/desktop/aa366770(v=vs.85).aspx
+type MemoryStatusEx struct {
+	Length               uint32
+	MemoryLoad           uint32
+	TotalPhys            uint64
+	AvailPhys            uint64
+	TotalPageFile        uint64
+	AvailPageFile        uint64
+	TotalVirtual         uint64
+	AvailVirtual         uint64
+	AvailExtendedVirtual uint64
+}
+
 var (
-	modkernel32                            = syscall.NewLazyDLL("kernel32.dll")
+	modkernel32              = windows.NewLazySystemDLL("kernel32.dll")
-	procGetPhysicallyInstalledSystemMemory = modkernel32.NewProc("GetPhysicallyInstalledSystemMemory")
+	procGlobalMemoryStatusEx = modkernel32.NewProc("GlobalMemoryStatusEx")
 )
 
 // NewPerfCounterClient creates a client using perf counters
@@ -163,20 +177,24 @@ func (p *perfCounterNodeStatsClient) convertCPUValue(cpuValue uint64) uint64 {
 }
 
 func getPhysicallyInstalledSystemMemoryBytes() (uint64, error) {
-	var physicalMemoryKiloBytes uint64
+	// We use GlobalMemoryStatusEx instead of GetPhysicallyInstalledSystemMemory
+	// on Windows node for the following reasons:
+	// 1. GetPhysicallyInstalledSystemMemory retrieves the amount of physically
+	// installed RAM from the computer's SMBIOS firmware tables.
+	// https://msdn.microsoft.com/en-us/library/windows/desktop/cc300158(v=vs.85).aspx
+	// On some VM, it is unable to read data from SMBIOS and fails with ERROR_INVALID_DATA.
+	// 2. On Linux node, total physical memory is read from MemTotal in /proc/meminfo.
+	// GlobalMemoryStatusEx returns the amount of physical memory that is available
+	// for the operating system to use. The amount returned by GlobalMemoryStatusEx
+	// is closer in parity with Linux
+	// https://www.kernel.org/doc/Documentation/filesystems/proc.txt
+	var statex MemoryStatusEx
+	statex.Length = uint32(unsafe.Sizeof(statex))
+	ret, _, _ := procGlobalMemoryStatusEx.Call(uintptr(unsafe.Pointer(&statex)))
 
-	if ok := getPhysicallyInstalledSystemMemory(&physicalMemoryKiloBytes); !ok {
+	if ret == 0 {
 		return 0, errors.New("unable to read physical memory")
 	}
 
-	return physicalMemoryKiloBytes * 1024, nil // convert kilobytes to bytes
+	return statex.TotalPhys, nil
-}
-
-func getPhysicallyInstalledSystemMemory(totalMemoryInKilobytes *uint64) bool {
-	ret, _, _ := syscall.Syscall(procGetPhysicallyInstalledSystemMemory.Addr(), 1,
-		uintptr(unsafe.Pointer(totalMemoryInKilobytes)),
-		0,
-		0)
-
-	return ret != 0
 }