diff --git a/internal/metrics/systeminfo/system_info.go b/internal/metrics/systeminfo/system_info.go
index 569967de..abe37b96 100644
--- a/internal/metrics/systeminfo/system_info.go
+++ b/internal/metrics/systeminfo/system_info.go
@@ -172,6 +172,45 @@ func (s *SystemInfo) collectMemoryInfo(ctx context.Context) error {
 	return nil
 }
 
+func shouldExcludeDisk(name string) bool {
+	// include only sd* and nvme* disk devices
+	// but not partitions like nvme0p1
+
+	if len(name) < 3 {
+		return true
+	}
+	switch {
+	case strings.HasPrefix(name, "nvme"),
+		strings.HasPrefix(name, "mmcblk"): // NVMe/SD/MMC
+		s := name[len(name)-2]
+		// skip namespaces/partitions
+		switch s {
+		case 'p', 'n':
+			return true
+		default:
+			return false
+		}
+	}
+	switch name[0] {
+	case 's', 'h', 'v': // SCSI/SATA/virtio disks
+		if name[1] != 'd' {
+			return true
+		}
+	case 'x': // Xen virtual disks
+		if name[1:3] != "vd" {
+			return true
+		}
+	default:
+		return true
+	}
+	last := name[len(name)-1]
+	if last >= '0' && last <= '9' {
+		// skip partitions
+		return true
+	}
+	return false
+}
+
 func (s *SystemInfo) collectDisksInfo(ctx context.Context, lastResult *SystemInfo) error {
 	ioCounters, err := disk.IOCountersWithContext(ctx)
 	if err != nil {
@@ -179,34 +218,9 @@ func (s *SystemInfo) collectDisksInfo(ctx context.Context, lastResult *SystemInf
 	}
 	s.DisksIO = make(map[string]*DiskIO, len(ioCounters))
 	for name, io := range ioCounters {
-		// include only /dev/sd* and /dev/nvme* disk devices
-		if len(name) < 3 {
+		if shouldExcludeDisk(name) {
 			continue
 		}
-		switch {
-		case strings.HasPrefix(name, "nvme"),
-			strings.HasPrefix(name, "mmcblk"): // NVMe/SD/MMC
-			if name[len(name)-2] == 'p' {
-				continue // skip partitions
-			}
-		default:
-			switch name[0] {
-			case 's', 'h', 'v': // SCSI/SATA/virtio disks
-				if name[1] != 'd' {
-					continue
-				}
-			case 'x': // Xen virtual disks
-				if name[1:3] != "vd" {
-					continue
-				}
-			default:
-				continue
-			}
-			last := name[len(name)-1]
-			if last >= '0' && last <= '9' {
-				continue // skip partitions
-			}
-		}
 		s.DisksIO[name] = &DiskIO{
 			ReadBytes:  io.ReadBytes,
 			WriteBytes: io.WriteBytes,
diff --git a/internal/metrics/systeminfo/system_info_test.go b/internal/metrics/systeminfo/system_info_test.go
index dc061fde..65790697 100644
--- a/internal/metrics/systeminfo/system_info_test.go
+++ b/internal/metrics/systeminfo/system_info_test.go
@@ -10,6 +10,73 @@ import (
 	. "github.com/yusing/go-proxy/internal/utils/testing"
 )
 
+func TestExcludeDisks(t *testing.T) {
+	tests := []struct {
+		name          string
+		shouldExclude bool
+	}{
+		{
+			name:          "nvme0",
+			shouldExclude: false,
+		},
+		{
+			name:          "nvme0n1",
+			shouldExclude: true,
+		},
+		{
+			name:          "nvme0n1p1",
+			shouldExclude: true,
+		},
+		{
+			name:          "sda",
+			shouldExclude: false,
+		},
+		{
+			name:          "sda1",
+			shouldExclude: true,
+		},
+		{
+			name:          "hda",
+			shouldExclude: false,
+		},
+		{
+			name:          "vda",
+			shouldExclude: false,
+		},
+		{
+			name:          "xvda",
+			shouldExclude: false,
+		},
+		{
+			name:          "xva",
+			shouldExclude: true,
+		},
+		{
+			name:          "loop0",
+			shouldExclude: true,
+		},
+		{
+			name:          "mmcblk0",
+			shouldExclude: false,
+		},
+		{
+			name:          "mmcblk0p1",
+			shouldExclude: true,
+		},
+		{
+			name:          "ab",
+			shouldExclude: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := shouldExcludeDisk(tt.name)
+			ExpectEqual(t, result, tt.shouldExclude)
+		})
+	}
+}
+
 // Create test data
 var cpuAvg = 45.67
 var testInfo = &SystemInfo{
@@ -118,7 +185,7 @@ func TestSystemInfo(t *testing.T) {
 
 func TestSerialize(t *testing.T) {
 	entries := make([]*SystemInfo, 5)
-	for i := 0; i < 5; i++ {
+	for i := range 5 {
 		entries[i] = testInfo
 	}
 	for _, query := range allQueries {
@@ -140,9 +207,9 @@ func TestSerialize(t *testing.T) {
 	}
 }
 
-func BenchmarkSerialize(b *testing.B) {
+func BenchmarkJSONMarshal(b *testing.B) {
 	entries := make([]*SystemInfo, b.N)
-	for i := 0; i < b.N; i++ {
+	for i := range b.N {
 		entries[i] = testInfo
 	}
 	queries := map[string]Aggregated{}
@@ -153,14 +220,14 @@ func BenchmarkSerialize(b *testing.B) {
 	b.ReportAllocs()
 	b.ResetTimer()
 	b.Run("optimized", func(b *testing.B) {
-		for i := 0; i < b.N; i++ {
+		for b.Loop() {
 			for _, query := range allQueries {
 				_, _ = queries[query].MarshalJSON()
 			}
 		}
 	})
 	b.Run("json", func(b *testing.B) {
-		for i := 0; i < b.N; i++ {
+		for b.Loop() {
 			for _, query := range allQueries {
 				_, _ = json.Marshal([]map[string]any(queries[query]))
 			}