Fold the leftover formatters into the SI ones and stop reallocating the draw scratch

.gitignore

@@ -1,2 +1 @@
-/cabletest
 /shots/

fb.go

@@ -34,6 +34,7 @@ type scanout struct {
 type framebuffer struct {
 	fd      int
 	back    []byte
+	scratch []byte
 	w       int
 	h       int
 	pw      int
@@ -252,6 +253,7 @@ func openFramebuffer() (*framebuffer, error) {
 		}
 	}
 	fb.back = make([]byte, fb.stride*fb.ph)
+	fb.scratch = make([]byte, fb.stride)
 
 	set := drm.ModeCrtc{
 		SetConnectorsPtr: uint64(uintptr(unsafe.Pointer(&fb.connID))),
@@ -316,15 +318,22 @@ type rgb struct {
 
 func pixel(c rgb) uint32 { return drm.Pack(c.r, c.g, c.b) }
 
-func (fb *framebuffer) fill(c rgb) {
+// A run of one repeated pixel, reused between calls: a whole panel row is the
+// longest anything here needs, and every draw is on the one render goroutine.
+func (fb *framebuffer) pixelRun(n int, c rgb) []byte {
 	v := pixel(c)
-	row := make([]byte, fb.stride)
-	for x := 0; x+4 <= fb.stride; x += 4 {
-		row[x+0] = byte(v)
-		row[x+1] = byte(v >> 8)
-		row[x+2] = byte(v >> 16)
-		row[x+3] = byte(v >> 24)
+	s := fb.scratch[:n]
+	for i := 0; i+4 <= n; i += 4 {
+		s[i+0] = byte(v)
+		s[i+1] = byte(v >> 8)
+		s[i+2] = byte(v >> 16)
+		s[i+3] = byte(v >> 24)
 	}
+	return s
+}
+
+func (fb *framebuffer) fill(c rgb) {
+	row := fb.pixelRun(fb.stride, c)
 	for y := 0; y < fb.ph; y++ {
 		copy(fb.back[y*fb.stride:], row)
 	}
@@ -337,14 +346,7 @@ func (fb *framebuffer) rect(x0, y0, w, h int, c rgb) {
 	if x0 >= x1 || y0 >= y1 {
 		return
 	}
-	v := pixel(c)
-	span := make([]byte, (y1-y0)*4)
-	for i := 0; i+4 <= len(span); i += 4 {
-		span[i+0] = byte(v)
-		span[i+1] = byte(v >> 8)
-		span[i+2] = byte(v >> 16)
-		span[i+3] = byte(v >> 24)
-	}
+	span := fb.pixelRun((y1-y0)*4, c)
 	for x := x0; x < x1; x++ {
 		copy(fb.back[fb.offset(x, y1-1):], span)
 	}

main.go

@@ -57,7 +57,7 @@ type direction struct {
 	base        counterSet
 
 	heldFrames heldValue
-	heldSent   heldValue
+	heldBytes  heldValue
 	nic        atomic.Uint64
 	poller     *nicPoller
 }
@@ -253,7 +253,7 @@ func (d *direction) reset() {
 	d.mu.Unlock()
 
 	d.heldFrames = heldValue{}
-	d.heldSent = heldValue{}
+	d.heldBytes = heldValue{}
 	d.cable.reset()
 }
 
@@ -299,7 +299,7 @@ var intervalCols = []colSpec{
 type view struct {
 	txPPS, rxPPS      float64
 	txGbps, rxGbps    float64
-	rxFrames, rxGot uint64
+	rxFrames, rxBytes uint64
 	since             errs
 	window            errs
 	cable             cableView
@@ -326,7 +326,7 @@ func errsBetween(b, n counterSet) errs {
 func (d *direction) counters(now counterSet) view {
 	return view{
 		rxFrames: now.s.rxFrames - d.base.s.rxFrames,
-		rxGot:    now.s.rxBytes - d.base.s.rxBytes,
+		rxBytes:  now.s.rxBytes - d.base.s.rxBytes,
 		cable:    d.cable.view(),
 		since:    errsBetween(d.base, now),
 	}
@@ -340,7 +340,7 @@ func totalView(views []view) view {
 		t.txGbps += v.txGbps
 		t.rxGbps += v.rxGbps
 		t.rxFrames += v.rxFrames
-		t.rxGot += v.rxGot
+		t.rxBytes += v.rxBytes
 		t.since = t.since.add(v.since)
 		t.window = t.window.add(v.window)
 	}
@@ -393,7 +393,7 @@ func (d *direction) displayView(t time.Time) view {
 	d.mu.Unlock()
 
 	v.rxFrames = d.heldFrames.get(t, v.rxFrames)
-	v.rxGot = d.heldSent.get(t, v.rxGot)
+	v.rxBytes = d.heldBytes.get(t, v.rxBytes)
 	return v
 }
 
@@ -678,9 +678,9 @@ func run(aName, bName string, nsPerM float64) error {
 			{"probe", fmt.Sprintf("ethertype 0x%04x every %s", probeEther, probeInterval)},
 			{"batch", fmt.Sprintf("%d frames per syscall", batchSize)},
 			{"calibration", fmt.Sprintf("%g ns/m, zero taken from the shortest delay seen so far", nsPerM)},
-			{"buffers", fmt.Sprintf("sndbuf %s, rcvbuf %s",
-				humanBytes(uint64(sockBufSize(dirs[0].txFDs[0], unix.SO_SNDBUF))),
-				humanBytes(uint64(sockBufSize(dirs[0].rxFDs[0], unix.SO_RCVBUF))))},
+			{"buffers", fmt.Sprintf("sndbuf %sB, rcvbuf %sB",
+				scaleCount(uint64(sockBufSize(dirs[0].txFDs[0], unix.SO_SNDBUF))),
+				scaleCount(uint64(sockBufSize(dirs[0].rxFDs[0], unix.SO_RCVBUF))))},
 		}))
 	fmt.Println()
 

main_test.go

@@ -26,8 +26,8 @@ func TestResetDoesNotUnderflowTotals(t *testing.T) {
 	if v.rxFrames != 0 {
 		t.Errorf("rxFrames = %d, want 0", v.rxFrames)
 	}
-	if v.rxGot != 0 {
-		t.Errorf("rxGot = %d, want 0", v.rxGot)
+	if v.rxBytes != 0 {
+		t.Errorf("rxBytes = %d, want 0", v.rxBytes)
 	}
 
 	// The rolling window and the rates are about now rather than since the

probe.go

@@ -49,7 +49,7 @@ func (v cableView) minText() string {
 	if !v.ok {
 		return "-"
 	}
-	return commasInt(v.min)
+	return commas(uint64(v.min))
 }
 
 // Averaging the two directions cancels the phy asymmetry between them, which is

render.go

@@ -71,25 +71,6 @@ func commas(v uint64) string {
 	return strings.Join(append([]string{s}, parts...), ",")
 }
 
-func commasInt(v int64) string {
-	if v < 0 {
-		return "-" + commas(uint64(-v))
-	}
-	return commas(uint64(v))
-}
-
-func humanBytes(b uint64) string {
-	const unit = 1000.0
-	v := float64(b)
-	for _, suffix := range []string{"B", "kB", "MB", "GB", "TB"} {
-		if v < unit {
-			return fmt.Sprintf("%.1f %s", v, suffix)
-		}
-		v /= unit
-	}
-	return fmt.Sprintf("%.1f PB", v)
-}
-
 // The magnitude letter goes with the figure so the unit can stay a fixed word
 // on the label. Below a thousand no letter is left dangling, since a trailing
 // space would push the figure off centre.

ui.go

@@ -344,7 +344,7 @@ func (d *display) render(v view, elapsed time.Duration, cable string) error {
 	d.stats(d.gridB, x, w, d.sinceYs[0], []statCell{
 		{scaleTime(elapsed), "elapsed", uiFg},
 		{scaleCount(v.rxFrames), "packets", uiFg},
-		{scaleCount(v.rxGot), "bytes", uiFg},
+		{scaleCount(v.rxBytes), "bytes", uiFg},
 		{cable, "m", uiFg},
 	})
 	d.errCounts(x, w, d.sinceYs[1], v.since)