Count link and syscall failures instead of printing them

main.go

@@ -44,7 +44,6 @@ type direction struct {
 	streams []lossWindow
 	txFDs   []int
 	rxFDs   []int
-	reports chan string
 
 	probeSpec *frameSpec
 	probeTxFD int
@@ -59,8 +58,8 @@ type direction struct {
 	drops       uint64
 	errBase     sample
 	dropBase    uint64
-	nicTX       nicCounters
-	nicRX       nicCounters
+	nicNow      uint64
+	nicBase     uint64
 }
 
 // Smoothing has to be steady against high-frequency noise yet still chase a
@@ -192,6 +191,7 @@ type sample struct {
 	crcErr, badMagic  uint64
 	badLen            uint64
 	txErrs, txShort   uint64
+	rxErrs            uint64
 }
 
 func lookupEndpoint(name string) (endpoint, error) {
@@ -247,6 +247,7 @@ func (d *direction) snapshot() sample {
 		s.crcErr += r.crcErr.Load()
 		s.badMagic += r.badMagic.Load()
 		s.badLen += r.badLen.Load()
+		s.rxErrs += r.rxErrs.Load()
 	}
 	for i := range d.streams {
 		s.lost += d.streams[i].lost.Load()
@@ -264,6 +265,7 @@ func (d *direction) reset() {
 	d.dropBase = d.drops
 	d.heldFrames = heldValue{}
 	d.heldSent = heldValue{}
+	d.nicBase = d.nicNow
 	d.cable.reset()
 }
 
@@ -300,7 +302,8 @@ var intervalCols = []colSpec{
 	{title: "CRC", width: 7, right: true},
 	{title: "BADMAG", width: 7, right: true},
 	{title: "KDROP", width: 11, right: true},
-	{title: "ERRORS", width: 11, right: true},
+	{title: "LINK", width: 13, right: true},
+	{title: "ERRORS", width: 13, right: true},
 	{title: "MIN ns", width: 9, right: true},
 	{title: "LEN m", width: 6, right: true},
 }
@@ -314,7 +317,8 @@ type view struct {
 	rxFrames, rxGot  uint64
 	lost, late       uint64
 	crc, badMagic    uint64
-	kdrop, errors    uint64
+	kdrop, link      uint64
+	errors           uint64
 	cable            cableView
 }
 
@@ -334,7 +338,12 @@ func (d *direction) counters(now sample) view {
 		kdrop:    d.drops - d.dropBase,
 		cable:    d.cable.view(),
 	}
-	v.errors = v.lost + v.crc + v.badMagic + (now.badLen - b.badLen) + v.kdrop
+	// A frame the stack refused and a frame the driver dropped are the same
+	// failure seen from either side of the ring, and never the same frame twice:
+	// a send that fails never reaches the driver to be dropped.
+	v.link = d.nicNow - d.nicBase +
+		(now.txErrs - b.txErrs) + (now.rxErrs - b.rxErrs)
+	v.errors = v.lost + v.crc + v.badMagic + (now.badLen - b.badLen) + v.kdrop + v.link
 	return v
 }
 
@@ -398,25 +407,19 @@ func (d *direction) row(elapsed time.Duration, v view, target float64, length st
 		statusCell(v.crc),
 		statusCell(v.badMagic),
 		statusCell(v.kdrop),
+		statusCell(v.link),
 		statusCell(v.errors),
 		paint(v.cable.minText(), cCyan),
 		paint(length, cCyan),
 	}
 }
 
-func (d *direction) reportNIC() []string {
+// Read once a second rather than per frame, since these are sysfs files; the
+// display uses whatever the last sample left behind.
+func (d *direction) sampleNIC() {
 	tx := readNIC(d.tx.name)
 	rx := readNIC(d.rx.name)
-	var parts []string
-	if s := tx.diff(d.nicTX); s != "" {
-		parts = append(parts, paint("  ▲ "+d.tx.name+" tx-side: "+s, cYellow))
-	}
-	if s := rx.diff(d.nicRX); s != "" {
-		parts = append(parts, paint("  ▲ "+d.rx.name+" rx-side: "+s, cYellow))
-	}
-	d.nicTX = tx
-	d.nicRX = rx
-	return parts
+	d.nicNow = tx.tx + rx.rx + tx.carrierDown
 }
 
 func buildDirection(label string, tx, rx endpoint, patIdx int, sizes []int, cfg config) (*direction, error) {
@@ -426,10 +429,8 @@ func buildDirection(label string, tx, rx endpoint, patIdx int, sizes []int, cfg
 		tx:      tx,
 		rx:      rx,
 		streams: newLossWindows(cfg.streams),
-		reports: make(chan string, 64),
+		cable:   newCableStats(),
 	}
-	d.nicTX = readNIC(tx.name)
-	d.nicRX = readNIC(rx.name)
 
 	for i := 0; i < cfg.streams; i++ {
 		et := uint16(etherBase + i)
@@ -453,7 +454,6 @@ func buildDirection(label string, tx, rx endpoint, patIdx int, sizes []int, cfg
 	// The probe carries its own ethertype so it lands on a socket of its own, but
 	// it is left unsteered: it is a few frames a second and does not need a queue
 	// to itself, and the stamps are taken at the wire either way.
-	d.cable = newCableStats()
 	d.probeSpec = newFrameSpec(patIdx, rx.mac, tx.mac, cfg.probeEther, []int{probeSize})
 	fd, err := openTxSocket(tx.idx)
 	if err != nil {
@@ -471,6 +471,10 @@ func buildDirection(label string, tx, rx endpoint, patIdx int, sizes []int, cfg
 		return nil, fmt.Errorf("%s probe rx timestamps: %w", label, err)
 	}
 	d.probeRxFD = fd
+
+	// Whatever the interfaces have counted before now is not ours.
+	d.sampleNIC()
+	d.nicBase = d.nicNow
 	return d, nil
 }
 
@@ -497,7 +501,6 @@ func (d *direction) start(wg *sync.WaitGroup, doneTx, doneRx *atomic.Bool, cfg c
 			spec:    d.specs[i],
 			stats:   d.rxStats[i],
 			streams: d.streams,
-			reports: d.reports,
 			ready:   rxReady,
 		}
 		wg.Add(1)
@@ -762,6 +765,7 @@ func run(aName, bName, sizesArg, patArg string,
 			// Length needs both directions, so every row is sampled before any of
 			// them is printed.
 			for i, d := range dirs {
+				d.sampleNIC()
 				rows[i] = d.view(&d.prevConsole, secs)
 			}
 			length := "-"
@@ -772,18 +776,6 @@ func run(aName, bName, sizesArg, patArg string,
 				for _, line := range stats.emit(d.row(elapsed, rows[i], target, length)) {
 					fmt.Println(line)
 				}
-				for _, line := range d.reportNIC() {
-					fmt.Println(line)
-				}
-				for {
-					select {
-					case msg := <-d.reports:
-						fmt.Println(paint("  ✗ "+d.short+": "+msg, cRed))
-						continue
-					default:
-					}
-					break
-				}
 			}
 		}
 	}