tests: avoid use of loopback dialer in Benchmark{Parallel,}Sysbench

When follow-the-workload is disabled (#153865), leases no longer
reliably stay on n1. Since the workload clients are always
created on n1, they were able to use the loopback dialer (which
avoids going through the TCP layer by using inter-progress
communication instead) prior to that change.
We want these benchmarks to be independent of lease placement,
so we disable the loopback dialer. That this was not done
initially is likely an oversight.

This commit will cause a a benchmark regression, but it is
due to changing what is being benchmarked. The regression
does not result in any production change.

Author: tbg

pkg/sql/tests/BUILD.bazel

@@ -89,6 +89,7 @@ go_test(
         "//pkg/kv/kvserver/concurrency",
         "//pkg/multitenant/tenantcapabilitiespb",
         "//pkg/roachpb",
+        "//pkg/rpc",
         "//pkg/rpc/nodedialer",
         "//pkg/security/securityassets",
         "//pkg/security/securitytest",

pkg/sql/tests/sysbench_test.go

@@ -27,7 +27,9 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/kv"
 	"github.com/cockroachdb/cockroach/pkg/kv/kvpb"
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
+	"github.com/cockroachdb/cockroach/pkg/rpc"
 	"github.com/cockroachdb/cockroach/pkg/rpc/nodedialer"
+	"github.com/cockroachdb/cockroach/pkg/server"
 	"github.com/cockroachdb/cockroach/pkg/settings/cluster"
 	"github.com/cockroachdb/cockroach/pkg/sql"
 	"github.com/cockroachdb/cockroach/pkg/testutils/serverutils"
@@ -164,25 +166,27 @@ func newTestCluster(
 	// also moderately less realistic.
 	disableBackgroundWork(st)
 	const cacheSize = 2 * 1024 * 1024 * 1024 // 2GB
+	knobs := base.TestingKnobs{
+		DialerKnobs: nodedialer.DialerTestingKnobs{
+			TestingNoLocalClientOptimization: !localRPCFastPath,
+		},
+		Server: &server.TestingKnobs{
+			ContextTestingKnobs: rpc.ContextTestingKnobs{
+				NoLoopbackDialer: !localRPCFastPath,
+			},
+		},
+	}
 	return serverutils.StartCluster(b, nodes, base.TestClusterArgs{
 		ServerArgs: base.TestServerArgs{
 			Settings:  st,
 			CacheSize: cacheSize,
-			Knobs: base.TestingKnobs{
-				DialerKnobs: nodedialer.DialerTestingKnobs{
-					TestingNoLocalClientOptimization: !localRPCFastPath,
-				},
-			},
+			Knobs:     knobs,
 		}},
 	)
 }
 
 // sysbenchSQL is SQL-based implementation of sysbenchDriver. It runs SQL
 // statements against a single node cluster.
-//
-// TODO(nvanbenschoten): add a 3-node cluster variant of this driver.
-// TODO(nvanbenschoten): add a variant of this driver which bypasses the gRPC
-// local fast-path optimization.
 type sysbenchSQL struct {
 	ctx     context.Context
 	stopper *stop.Stopper
@@ -376,10 +380,6 @@ func (s *sysbenchSQLClient) prepConn() {
 // sysbenchKV is KV-based implementation of sysbenchDriver. It bypasses the SQL
 // layer and runs the workload directly against the KV layer, on a single node
 // cluster.
-//
-// TODO(nvanbenschoten): add a 3-node cluster variant of this driver.
-// TODO(nvanbenschoten): add a variant of this driver which bypasses the gRPC
-// local fast-path optimization.
 type sysbenchKV struct {
 	ctx         context.Context
 	db          *kv.DB