Add full-duplex raw-Ethernet 10G cable stress tester

rx.go

@@ -0,0 +1,106 @@
+package main
+
+import (
+	"fmt"
+	"hash/crc32"
+	"sync"
+	"sync/atomic"
+
+	"golang.org/x/sys/unix"
+)
+
+type rxStats struct {
+	frames   atomic.Uint64
+	bytes    atomic.Uint64
+	badMagic atomic.Uint64
+	badLen   atomic.Uint64
+	crcErr   atomic.Uint64
+	_        [24]byte
+}
+
+type streamState struct {
+	maxSeq atomic.Uint64
+	count  atomic.Uint64
+	_      [48]byte
+}
+
+type rxWorker struct {
+	fd      int
+	batch   int
+	cpu     int
+	verify  bool
+	spec    *frameSpec
+	stats   *rxStats
+	streams []streamState
+	reports chan string
+	ready   *sync.WaitGroup
+}
+
+func (w *rxWorker) run(done *atomic.Bool) {
+	pinTo(w.cpu)
+
+	bufs := make([][]byte, w.batch)
+	for i := range bufs {
+		bufs[i] = make([]byte, maxFrame)
+		for j := 0; j < maxFrame; j += 4096 {
+			bufs[i][j] = 0
+		}
+	}
+	hdrs, _ := newMmsghdrs(bufs)
+
+	w.ready.Done()
+
+	for !done.Load() {
+		n, err := recvmmsg(w.fd, hdrs, unix.MSG_WAITFORONE)
+		if n <= 0 {
+			if err != nil && err != unix.EAGAIN && err != unix.EINTR {
+				w.report(fmt.Sprintf("recvmmsg: %v", err))
+			}
+			continue
+		}
+		for i := 0; i < n; i++ {
+			buf := bufs[i][:int(hdrs[i].len)]
+			p, ok := parseHeader(buf)
+			if !ok {
+				w.stats.badMagic.Add(1)
+				continue
+			}
+			w.stats.frames.Add(1)
+			w.stats.bytes.Add(uint64(len(buf)))
+
+			if int(p.stream) < len(w.streams) {
+				st := &w.streams[p.stream]
+				st.count.Add(1)
+				for {
+					old := st.maxSeq.Load()
+					if p.seq <= old || st.maxSeq.CompareAndSwap(old, p.seq) {
+						break
+					}
+				}
+			}
+
+			if !w.verify {
+				continue
+			}
+			if p.payLen > len(w.spec.ref) {
+				w.stats.badLen.Add(1)
+				continue
+			}
+			pay := buf[minFrame : minFrame+p.payLen]
+			if crc32.Checksum(pay, crcTable) == p.crc {
+				continue
+			}
+			w.stats.crcErr.Add(1)
+			off, bits := firstDiff(pay, w.spec.ref[:p.payLen])
+			w.report(fmt.Sprintf("payload mismatch stream=%d seq=%d len=%d first-diff-offset=%d bits=%d",
+				p.stream, p.seq, p.payLen, off, bits))
+		}
+	}
+}
+
+func (w *rxWorker) report(msg string) {
+	select {
+	case w.reports <- msg:
+	default:
+	}
+}