Use guest meminfo available for VM memory usage

internal/monitoring/diagnostic_snapshots.go

@@ -49,6 +49,10 @@ type VMMemoryRaw struct {
 	MemInfoUsed      uint64 `json:"meminfoUsed,omitempty"`
 	MemInfoFree      uint64 `json:"meminfoFree,omitempty"`
 	MemInfoTotal     uint64 `json:"meminfoTotal,omitempty"`
+	MemInfoAvailable uint64 `json:"meminfoAvailable,omitempty"`
+	MemInfoBuffers   uint64 `json:"meminfoBuffers,omitempty"`
+	MemInfoCached    uint64 `json:"meminfoCached,omitempty"`
+	MemInfoShared    uint64 `json:"meminfoShared,omitempty"`
 	Agent            int    `json:"agent,omitempty"`
 	DerivedFromBall  bool   `json:"derivedFromBalloon,omitempty"`
 }

internal/monitoring/monitor.go

@@ -2527,10 +2527,28 @@ func (m *Monitor) pollVMsAndContainersEfficient(ctx context.Context, instanceNam
 					guestRaw.Balloon = detailedStatus.Balloon
 					guestRaw.BalloonMin = detailedStatus.BalloonMin
 					guestRaw.Agent = detailedStatus.Agent
+					memAvailable := uint64(0)
 					if detailedStatus.MemInfo != nil {
 						guestRaw.MemInfoUsed = detailedStatus.MemInfo.Used
 						guestRaw.MemInfoFree = detailedStatus.MemInfo.Free
 						guestRaw.MemInfoTotal = detailedStatus.MemInfo.Total
+						guestRaw.MemInfoAvailable = detailedStatus.MemInfo.Available
+						guestRaw.MemInfoBuffers = detailedStatus.MemInfo.Buffers
+						guestRaw.MemInfoCached = detailedStatus.MemInfo.Cached
+						guestRaw.MemInfoShared = detailedStatus.MemInfo.Shared
+
+						switch {
+						case detailedStatus.MemInfo.Available > 0:
+							memAvailable = detailedStatus.MemInfo.Available
+							memorySource = "meminfo-available"
+						case detailedStatus.MemInfo.Free > 0 ||
+							detailedStatus.MemInfo.Buffers > 0 ||
+							detailedStatus.MemInfo.Cached > 0:
+							memAvailable = detailedStatus.MemInfo.Free +
+								detailedStatus.MemInfo.Buffers +
+								detailedStatus.MemInfo.Cached
+							memorySource = "meminfo-derived"
+						}
 					}
 
 					// Use actual disk I/O values from detailed status
@@ -2547,10 +2565,16 @@ func (m *Monitor) pollVMsAndContainersEfficient(ctx context.Context, instanceNam
 						guestRaw.DerivedFromBall = false
 					}
 
-					if detailedStatus.FreeMem > 0 && memTotal >= detailedStatus.FreeMem {
+					switch {
+					case memAvailable > 0:
+						if memAvailable > memTotal {
+							memAvailable = memTotal
+						}
+						memUsed = memTotal - memAvailable
+					case detailedStatus.FreeMem > 0 && memTotal >= detailedStatus.FreeMem:
 						memUsed = memTotal - detailedStatus.FreeMem
 						memorySource = "status-freemem"
-					} else if detailedStatus.Mem > 0 {
+					case detailedStatus.Mem > 0:
 						memUsed = detailedStatus.Mem
 						memorySource = "status-mem"
 					}
@@ -3180,10 +3204,28 @@ func (m *Monitor) pollVMsWithNodes(ctx context.Context, instanceName string, cli
 					guestRaw.Balloon = status.Balloon
 					guestRaw.BalloonMin = status.BalloonMin
 					guestRaw.Agent = status.Agent
+					memAvailable := uint64(0)
 					if status.MemInfo != nil {
 						guestRaw.MemInfoUsed = status.MemInfo.Used
 						guestRaw.MemInfoFree = status.MemInfo.Free
 						guestRaw.MemInfoTotal = status.MemInfo.Total
+						guestRaw.MemInfoAvailable = status.MemInfo.Available
+						guestRaw.MemInfoBuffers = status.MemInfo.Buffers
+						guestRaw.MemInfoCached = status.MemInfo.Cached
+						guestRaw.MemInfoShared = status.MemInfo.Shared
+
+						switch {
+						case status.MemInfo.Available > 0:
+							memAvailable = status.MemInfo.Available
+							memorySource = "meminfo-available"
+						case status.MemInfo.Free > 0 ||
+							status.MemInfo.Buffers > 0 ||
+							status.MemInfo.Cached > 0:
+							memAvailable = status.MemInfo.Free +
+								status.MemInfo.Buffers +
+								status.MemInfo.Cached
+							memorySource = "meminfo-derived"
+						}
 					}
 
 					// Use actual disk I/O values from detailed status
@@ -3201,18 +3243,28 @@ func (m *Monitor) pollVMsWithNodes(ctx context.Context, instanceName string, cli
 					}
 
 					// If we have free memory from guest agent, calculate actual usage
-					if status.FreeMem > 0 {
+					switch {
+					case memAvailable > 0:
+						if memAvailable > memTotal {
+							memAvailable = memTotal
+						}
+						memUsed = memTotal - memAvailable
+					case status.FreeMem > 0:
 						// Guest agent reports free memory, so calculate used
 						memUsed = memTotal - status.FreeMem
 						memorySource = "status-freemem"
-					} else if status.Mem > 0 {
+					case status.Mem > 0:
 						// No guest agent free memory data, but we have actual memory usage
 						// Use the reported memory usage from Proxmox
 						memUsed = status.Mem
 						memorySource = "status-mem"
-					} else {
+					default:
 						// No memory data available at all - show 0% usage
 						memUsed = 0
+						memorySource = "status-unavailable"
+					}
+					if memUsed > memTotal {
+						memUsed = memTotal
 					}
 
 					guestIPs, guestIfaces, guestOSName, guestOSVersion := fetchGuestAgentMetadata(ctx, client, instanceName, node.Node, vm.Name, vm.VMID, status)
@@ -3456,6 +3508,25 @@ func (m *Monitor) pollVMsWithNodes(ctx context.Context, instanceName string, cli
 			}
 			diskReadRate, diskWriteRate, netInRate, netOutRate := m.rateTracker.CalculateRates(guestID, currentMetrics)
 
+			memTotalBytes := clampToInt64(memTotal)
+			memUsedBytes := clampToInt64(memUsed)
+			if memTotalBytes > 0 && memUsedBytes > memTotalBytes {
+				memUsedBytes = memTotalBytes
+			}
+			memFreeBytes := memTotalBytes - memUsedBytes
+			if memFreeBytes < 0 {
+				memFreeBytes = 0
+			}
+			memory := models.Memory{
+				Total: memTotalBytes,
+				Used:  memUsedBytes,
+				Free:  memFreeBytes,
+				Usage: safePercentage(float64(memUsed), float64(memTotal)),
+			}
+			if guestRaw.Balloon > 0 {
+				memory.Balloon = clampToInt64(guestRaw.Balloon)
+			}
+
 			modelVM := models.VM{
 				ID:       guestID,
 				VMID:     vm.VMID,
@@ -3466,12 +3537,7 @@ func (m *Monitor) pollVMsWithNodes(ctx context.Context, instanceName string, cli
 				Type:     "qemu",
 				CPU:      cpuUsage, // Already in percentage
 				CPUs:     vm.CPUs,
-				Memory: models.Memory{
+				Memory:   memory,
-					Total: int64(memTotal),
-					Used:  int64(memUsed),
-					Free:  int64(memTotal - memUsed),
-					Usage: safePercentage(float64(memUsed), float64(memTotal)),
-				},
 				Disk: models.Disk{
 					Total: int64(diskTotal),
 					Used:  int64(diskUsed),

internal/monitoring/monitor_optimized.go

@@ -163,21 +163,51 @@ func (m *Monitor) pollVMsWithNodesOptimized(ctx context.Context, instanceName st
 						guestRaw.Balloon = status.Balloon
 						guestRaw.BalloonMin = status.BalloonMin
 						guestRaw.Agent = status.Agent
+						memAvailable := uint64(0)
 						if status.MemInfo != nil {
 							guestRaw.MemInfoUsed = status.MemInfo.Used
 							guestRaw.MemInfoFree = status.MemInfo.Free
 							guestRaw.MemInfoTotal = status.MemInfo.Total
+							guestRaw.MemInfoAvailable = status.MemInfo.Available
+							guestRaw.MemInfoBuffers = status.MemInfo.Buffers
+							guestRaw.MemInfoCached = status.MemInfo.Cached
+							guestRaw.MemInfoShared = status.MemInfo.Shared
+
+							switch {
+							case status.MemInfo.Available > 0:
+								memAvailable = status.MemInfo.Available
+								memorySource = "meminfo-available"
+							case status.MemInfo.Free > 0 ||
+								status.MemInfo.Buffers > 0 ||
+								status.MemInfo.Cached > 0:
+								memAvailable = status.MemInfo.Free +
+									status.MemInfo.Buffers +
+									status.MemInfo.Cached
+								memorySource = "meminfo-derived"
+							}
 						}
 						if vmStatus.Balloon > 0 && vmStatus.Balloon < vmStatus.MaxMem {
 							memTotal = vmStatus.Balloon
 							guestRaw.DerivedFromBall = true
 						}
-						if vmStatus.FreeMem > 0 {
+						switch {
+						case memAvailable > 0:
+							if memAvailable > memTotal {
+								memAvailable = memTotal
+							}
+							memUsed = memTotal - memAvailable
+						case vmStatus.FreeMem > 0:
 							memUsed = memTotal - vmStatus.FreeMem
 							memorySource = "status-freemem"
-						} else if vmStatus.Mem > 0 {
+						case vmStatus.Mem > 0:
 							memUsed = vmStatus.Mem
 							memorySource = "status-mem"
+						default:
+							memUsed = 0
+							memorySource = "status-unavailable"
+						}
+						if memUsed > memTotal {
+							memUsed = memTotal
 						}
 						// Use actual disk I/O values from detailed status
 						diskReadBytes = int64(vmStatus.DiskRead)
@@ -461,14 +491,23 @@ func (m *Monitor) pollVMsWithNodesOptimized(ctx context.Context, instanceName st
 					diskStatusReason = "no-status"
 				}
 
+				memTotalBytes := clampToInt64(memTotal)
+				memUsedBytes := clampToInt64(memUsed)
+				if memTotalBytes > 0 && memUsedBytes > memTotalBytes {
+					memUsedBytes = memTotalBytes
+				}
+				memFreeBytes := memTotalBytes - memUsedBytes
+				if memFreeBytes < 0 {
+					memFreeBytes = 0
+				}
 				memory := models.Memory{
-					Total: int64(memTotal),
+					Total: memTotalBytes,
-					Used:  int64(memUsed),
+					Used:  memUsedBytes,
-					Free:  int64(memTotal - memUsed),
+					Free:  memFreeBytes,
 					Usage: safePercentage(float64(memUsed), float64(memTotal)),
 				}
-				if vmStatus != nil && vmStatus.Balloon > 0 {
+				if guestRaw.Balloon > 0 {
-					memory.Balloon = int64(vmStatus.Balloon)
+					memory.Balloon = clampToInt64(guestRaw.Balloon)
 				}
 
 				// Create VM model

pkg/proxmox/client.go

@@ -1243,6 +1243,21 @@ type ZFSPoolDevice struct {
 }
 
 // VMStatus represents detailed VM status
+// VMMemInfo describes memory statistics reported by the guest agent.
+// Proxmox surfaces guest /proc/meminfo values (in bytes). The available
+// field is only present on newer agent versions, so we keep the raw
+// components to reconstruct it when missing.
+type VMMemInfo struct {
+	Total     uint64 `json:"total,omitempty"`
+	Used      uint64 `json:"used,omitempty"`
+	Free      uint64 `json:"free,omitempty"`
+	Available uint64 `json:"available,omitempty"`
+	Buffers   uint64 `json:"buffers,omitempty"`
+	Cached    uint64 `json:"cached,omitempty"`
+	Shared    uint64 `json:"shared,omitempty"`
+}
+
+// VMStatus represents detailed VM status returned by Proxmox.
 type VMStatus struct {
 	Status     string     `json:"status"`
 	CPU        float64    `json:"cpu"`
@@ -1252,11 +1267,7 @@ type VMStatus struct {
 	Balloon    uint64     `json:"balloon"`
 	BalloonMin uint64     `json:"balloon_min"`
 	FreeMem    uint64     `json:"freemem"`
-	MemInfo    *struct {
+	MemInfo    *VMMemInfo `json:"meminfo,omitempty"`
-		Used  uint64 `json:"used"`
-		Free  uint64 `json:"free"`
-		Total uint64 `json:"total"`
-	} `json:"meminfo,omitempty"`
 	Disk       uint64     `json:"disk"`
 	MaxDisk    uint64     `json:"maxdisk"`
 	DiskRead   uint64     `json:"diskread"`