backup: disable AC in datadriven tests

These tests, via 'new-cluster', run a large number of nodes in a single process,
overloading that process and causing bulk work to starve if it is restricted to
using strictly spare capacity (of which there is none).

Release note: none.
Epic: none.

Author: dt

pkg/backup/datadriven_test.go

@@ -27,6 +27,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/jobs/jobspb"
 	"github.com/cockroachdb/cockroach/pkg/keys"
 	"github.com/cockroachdb/cockroach/pkg/kv"
+	"github.com/cockroachdb/cockroach/pkg/kv/bulk"
 	"github.com/cockroachdb/cockroach/pkg/kv/kvclient/kvcoord"
 	"github.com/cockroachdb/cockroach/pkg/kv/kvpb"
 	"github.com/cockroachdb/cockroach/pkg/kv/kvserver"
@@ -45,6 +46,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/testutils/serverutils"
 	"github.com/cockroachdb/cockroach/pkg/testutils/skip"
 	"github.com/cockroachdb/cockroach/pkg/testutils/sqlutils"
+	"github.com/cockroachdb/cockroach/pkg/util/admission"
 	"github.com/cockroachdb/cockroach/pkg/util/ctxgroup"
 	"github.com/cockroachdb/datadriven"
 	"github.com/cockroachdb/errors"
@@ -194,6 +196,12 @@ func (d *datadrivenTestState) addCluster(t *testing.T, cfg clusterCfg) error {
 	closedts.SideTransportCloseInterval.Override(context.Background(), &settings.SV, 10*time.Millisecond)
 	kvserver.RangeFeedRefreshInterval.Override(context.Background(), &settings.SV, 10*time.Millisecond)
 	sql.TempObjectWaitInterval.Override(context.Background(), &settings.SV, time.Millisecond)
+	// Disable AC yielding as these tests can run many in-process clusters at once
+	// and overload the host. Generally overload would mean bulk work, which only
+	// uses strictly spare capacitym gets starved, but these tests expect it to
+	// still run (just slowly, along with everything else).
+	bulk.YieldIfNoPacer.Override(context.Background(), &settings.SV, false)
+	admission.YieldInPacer.Override(context.Background(), &settings.SV, false)
 	params.ServerArgs.Settings = settings
 
 	clusterSize := cfg.nodes

pkg/kv/bulk/cpu_pacer.go

@@ -25,7 +25,8 @@ var cpuPacerRequestDuration = settings.RegisterDurationSetting(
 	50*time.Millisecond,
 )
 
-var yieldIfNoPacer = settings.RegisterBoolSetting(
+// YieldIfNoPacer is exported so it can be overridden in tests.
+var YieldIfNoPacer = settings.RegisterBoolSetting(
 	settings.ApplicationLevel,
 	"bulkio.elastic_cpu_control.always_yield.enabled",
 	"if true, yield the CPU as needed even when time-based elastic pacing is not enabled",
@@ -38,7 +39,7 @@ func NewCPUPacer(ctx context.Context, db *kv.DB, setting *settings.BoolSetting)
 	if db == nil || db.AdmissionPacerFactory == nil || !setting.Get(db.SettingsValues()) {
 		log.Dev.Infof(ctx, "admission control is not configured to pace bulk ingestion")
 
-		if db != nil && yieldIfNoPacer.Get(db.SettingsValues()) {
+		if db != nil && YieldIfNoPacer.Get(db.SettingsValues()) {
 			// Return a Pacer that just yields.
 			return &admission.Pacer{Yield: true}
 		}

pkg/util/admission/elastic_cpu_grant_coordinator.go

@@ -84,7 +84,8 @@ func (e *ElasticCPUGrantCoordinator) tryGrant() {
 	e.elasticCPUGranter.tryGrant()
 }
 
-var yieldInPacer = settings.RegisterBoolSetting(
+// YieldInPacer is exported so it can be overridden in tests.
+var YieldInPacer = settings.RegisterBoolSetting(
 	settings.ApplicationLevel,
 	"admission.elastic_cpu.yield_in_pacer.enabled",
 	"when true, time-based elastic CPU pacing additionally yields CPU as-needed according to the scheduler",
@@ -100,6 +101,6 @@ func (e *ElasticCPUGrantCoordinator) NewPacer(unit time.Duration, wi WorkInfo) *
 		unit:  unit,
 		wi:    wi,
 		wq:    e.ElasticCPUWorkQueue,
-		Yield: yieldInPacer.Get(&e.ElasticCPUWorkQueue.settings.SV),
+		Yield: YieldInPacer.Get(&e.ElasticCPUWorkQueue.settings.SV),
 	}
 }