Collapse errors into lost, corrupt, link and internal

main.go

@@ -94,24 +94,25 @@ func (d *direction) capture(t time.Time) counterSet {
 	return counterSet{t: t, s: d.snapshot(), drops: d.drops, nic: d.nic.Load()}
 }
 
-// Late is counted but left out of the total, since a reordered frame arrived.
+// What someone testing a cable is asking, rather than how each failure happened
+// to be noticed. Corruption arrives as three different symptoms and the kernel
+// drops frames for reasons that are ours rather than the cable's, but none of
+// that is a distinction worth reading off a panel.
 type errs struct {
-	lost, late    uint64
+	lost     uint64
-	crc, badMagic uint64
+	corrupt  uint64
-	badLen        uint64
+	link     uint64
-	kdrop, link   uint64
+	internal uint64
 }
 
 func (e errs) total() uint64 {
-	return e.lost + e.crc + e.badMagic + e.badLen + e.kdrop + e.link
+	return e.lost + e.corrupt + e.link + e.internal
 }
 
 func (e errs) add(o errs) errs {
 	return errs{
-		lost: e.lost + o.lost, late: e.late + o.late,
+		lost: e.lost + o.lost, corrupt: e.corrupt + o.corrupt,
-		crc: e.crc + o.crc, badMagic: e.badMagic + o.badMagic,
+		link: e.link + o.link, internal: e.internal + o.internal,
-		badLen: e.badLen + o.badLen,
-		kdrop:  e.kdrop + o.kdrop, link: e.link + o.link,
 	}
 }
 
@@ -309,11 +310,9 @@ var intervalCols = []colSpec{
 	{title: "RX pps", width: 9, right: true},
 	{title: "RX Gb/s", width: 7, right: true},
 	{title: "LOST", width: 11, right: true},
-	{title: "LATE", width: 9, right: true},
+	{title: "CORRUPT", width: 11, right: true},
-	{title: "CRC", width: 7, right: true},
+	{title: "LINK", width: 11, right: true},
-	{title: "BADMAG", width: 7, right: true},
+	{title: "INTERNAL", width: 11, right: true},
-	{title: "KDROP", 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},
@@ -332,16 +331,21 @@ type view struct {
 
 func errsBetween(b, n counterSet) errs {
 	return errs{
-		lost:     n.s.lost - b.s.lost,
+		lost: n.s.lost - b.s.lost,
-		late:     n.s.late - b.s.late,
+		// Three ways of noticing one thing: a payload that does not match its
-		crc:      n.s.crcErr - b.s.crcErr,
+		// checksum, a header that is not ours, and a length that cannot be.
-		badMagic: n.s.badMagic - b.s.badMagic,
+		corrupt: (n.s.crcErr - b.s.crcErr) + (n.s.badMagic - b.s.badMagic) +
-		badLen:   n.s.badLen - b.s.badLen,
+			(n.s.badLen - b.s.badLen),
-		kdrop:    n.drops - b.drops,
 		// 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.
 		link: (n.nic - b.nic) + (n.s.txErrs - b.s.txErrs) + (n.s.rxErrs - b.s.rxErrs),
+		// Ours rather than the cable's: frames the kernel threw away because we
+		// did not drain the ring fast enough, and frames so far out of order
+		// that our own bookkeeping had already written them off. The second is
+		// unreachable while each stream has a flow rule to its own queue, which
+		// is exactly why it is worth counting: it fires if that stops holding.
+		internal: (n.drops - b.drops) + (n.s.late - b.s.late),
 	}
 }
 
@@ -433,11 +437,9 @@ func (d *direction) row(elapsed time.Duration, v view, target float64, length st
 		commas(uint64(v.rxPPS)),
 		rateCell(v.rxGbps, target),
 		statusCell(v.since.lost),
-		statusCell(v.since.late),
+		statusCell(v.since.corrupt),
-		statusCell(v.since.crc),
-		statusCell(v.since.badMagic),
-		statusCell(v.since.kdrop),
 		statusCell(v.since.link),
+		statusCell(v.since.internal),
 		statusCell(v.since.total()),
 		paint(v.cable.minText(), cCyan),
 		paint(length, cCyan),

ui.go

@@ -195,12 +195,9 @@ var errRows = []struct {
 	get   func(errs) uint64
 }{
 	{"lost", func(e errs) uint64 { return e.lost }},
-	{"late", func(e errs) uint64 { return e.late }},
+	{"corrupt", func(e errs) uint64 { return e.corrupt }},
-	{"crc", func(e errs) uint64 { return e.crc }},
-	{"bad magic", func(e errs) uint64 { return e.badMagic }},
-	{"bad length", func(e errs) uint64 { return e.badLen }},
-	{"kernel drops", func(e errs) uint64 { return e.kdrop }},
 	{"link", func(e errs) uint64 { return e.link }},
+	{"internal", func(e errs) uint64 { return e.internal }},
 }
 
 func (d *display) errBlock(x, w, y int, e errs) int {