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

tx.go

@@ -0,0 +1,73 @@
+package main
+
+import (
+	"sync/atomic"
+
+	"golang.org/x/sys/unix"
+)
+
+type txStats struct {
+	frames atomic.Uint64
+	bytes  atomic.Uint64
+	errs   atomic.Uint64
+	short  atomic.Uint64
+	_      [32]byte
+}
+
+type txWorker struct {
+	fd      int
+	stream  uint16
+	spec    *frameSpec
+	batch   int
+	cpu     int
+	stats   *txStats
+	startTx <-chan struct{}
+}
+
+func (w *txWorker) run(done *atomic.Bool) {
+	pinTo(w.cpu)
+
+	bufs := make([][]byte, w.batch)
+	for i := range bufs {
+		bufs[i] = make([]byte, w.spec.maxSize)
+		w.spec.prefill(bufs[i])
+	}
+	hdrs, iovs := newMmsghdrs(bufs)
+	sizes := make([]int, w.batch)
+
+	<-w.startTx
+
+	var seq uint64
+	si := 0
+	for !done.Load() {
+		for i := 0; i < w.batch; i++ {
+			size := w.spec.sizes[si]
+			si++
+			if si == len(w.spec.sizes) {
+				si = 0
+			}
+			sizes[i] = size
+			putHeader(bufs[i], w.spec.patIdx, w.stream, seq+uint64(i), size-minFrame, w.spec.crcFor[size])
+			iovs[i].Len = uint64(size)
+		}
+
+		n, err := sendmmsg(w.fd, hdrs)
+		if n > 0 {
+			var b uint64
+			for i := 0; i < n; i++ {
+				b += uint64(sizes[i])
+			}
+			w.stats.frames.Add(uint64(n))
+			w.stats.bytes.Add(b)
+			seq += uint64(n)
+		}
+		if n < w.batch {
+			switch {
+			case n < 0 && err != unix.EINTR && err != unix.EAGAIN && err != unix.ENOBUFS:
+				w.stats.errs.Add(1)
+			default:
+				w.stats.short.Add(1)
+			}
+		}
+	}
+}