roachtest: add KV configurations with no manual splits

Before this PR we always ran our KV benchmarks with 1000 manual splits.
This is almost certainly too many. We preserve this value for the historical
continuity of the tests but add new configurations which do no manual
splitting.

Release note: None

pkg/cmd/roachtest/kv.go

@@ -34,11 +34,25 @@ func registerKV(r *testRegistry) {
 		readPercent int
 		batchSize   int
 		blockSize   int
+		splits      int // 0 implies default, negative implies 0
 		encryption  bool
 		sequential  bool
 		duration    time.Duration
 		tags        []string
 	}
+	computeNumSplits := func(opts kvOptions) int {
+		// TODO(ajwerner): set this default to a more sane value or remove it and
+		// rely on load-based splitting.
+		const defaultNumSplits = 1000
+		switch {
+		case opts.splits == 0:
+			return defaultNumSplits
+		case opts.splits < 0:
+			return 0
+		default:
+			return opts.splits
+		}
+	}
 	runKV := func(ctx context.Context, t *test, c *cluster, opts kvOptions) {
 		nodes := c.spec.NodeCount - 1
 		c.Put(ctx, cockroach, "./cockroach", c.Range(1, nodes))
@@ -49,7 +63,8 @@ func registerKV(r *testRegistry) {
 		m := newMonitor(ctx, c, c.Range(1, nodes))
 		m.Go(func(ctx context.Context) error {
 			concurrency := ifLocal("", " --concurrency="+fmt.Sprint(nodes*64))
-			splits := " --splits=1000"
+
+			splits := " --splits=" + strconv.Itoa(computeNumSplits(opts))
 			if opts.duration == 0 {
 				opts.duration = 10 * time.Minute
 			}
@@ -89,8 +104,12 @@ func registerKV(r *testRegistry) {
 		{nodes: 1, cpus: 32, readPercent: 95},
 		{nodes: 3, cpus: 8, readPercent: 0},
 		{nodes: 3, cpus: 8, readPercent: 95},
+		{nodes: 3, cpus: 8, readPercent: 0, splits: -1 /* no splits */},
+		{nodes: 3, cpus: 8, readPercent: 95, splits: -1 /* no splits */},
 		{nodes: 3, cpus: 32, readPercent: 0},
 		{nodes: 3, cpus: 32, readPercent: 95},
+		{nodes: 3, cpus: 32, readPercent: 0, splits: -1 /* no splits */},
+		{nodes: 3, cpus: 32, readPercent: 95, splits: -1 /* no splits */},
 
 		// Configs with large block sizes.
 		{nodes: 3, cpus: 8, readPercent: 0, blockSize: 1 << 12 /* 4 KB */},
@@ -143,6 +162,9 @@ func registerKV(r *testRegistry) {
 		if opts.blockSize != 0 { // support legacy test name which didn't include block size
 			nameParts = append(nameParts, fmt.Sprintf("size=%dkb", opts.blockSize>>10))
 		}
+		if opts.splits != 0 { // support legacy test name which didn't include splits
+			nameParts = append(nameParts, fmt.Sprintf("splt=%d", computeNumSplits(opts)))
+		}
 		if opts.sequential {
 			nameParts = append(nameParts, fmt.Sprintf("seq"))
 		}