admission: Disable AC for user requests

informs: cockroachdb#85641

Only leave admission control in place for elastic / bulk requests.

Release note: None

docs/generated/settings/settings.html

@@ -6,6 +6,7 @@
 <tr><td><code>admission.epoch_lifo.epoch_closing_delta_duration</code></td><td>duration</td><td><code>5ms</code></td><td>the delta duration before closing an epoch, for epoch-LIFO admission control ordering</td></tr>
 <tr><td><code>admission.epoch_lifo.epoch_duration</code></td><td>duration</td><td><code>100ms</code></td><td>the duration of an epoch, for epoch-LIFO admission control ordering</td></tr>
 <tr><td><code>admission.epoch_lifo.queue_delay_threshold_to_switch_to_lifo</code></td><td>duration</td><td><code>105ms</code></td><td>the queue delay encountered by a (tenant,priority) for switching to epoch-LIFO ordering</td></tr>
+<tr><td><code>admission.kv.bulk_only.enabled</code></td><td>boolean</td><td><code>false</code></td><td>when both admission.kv.enabled and this is true, only throttle bulk work</td></tr>
 <tr><td><code>admission.kv.enabled</code></td><td>boolean</td><td><code>true</code></td><td>when true, work performed by the KV layer is subject to admission control</td></tr>
 <tr><td><code>admission.kv.stores.tenant_weights.enabled</code></td><td>boolean</td><td><code>false</code></td><td>when true, tenant weights are enabled for KV-stores admission control</td></tr>
 <tr><td><code>admission.kv.tenant_weights.enabled</code></td><td>boolean</td><td><code>false</code></td><td>when true, tenant weights are enabled for KV admission control</td></tr>

pkg/kv/kvserver/store.go

@@ -3910,6 +3910,13 @@ func (n *KVAdmissionControllerImpl) AdmitKVWork(
 	if source == roachpb.AdmissionHeader_OTHER {
 		bypassAdmission = true
 	}
+	// TODO(abaptist): Revisit and deprecate this setting in v23.1.
+	if admission.KVBulkOnlyAdmissionControlEnabled.Get(&n.settings.SV) {
+		if admissionpb.WorkPriority(ba.AdmissionHeader.Priority) >= admissionpb.NormalPri {
+			bypassAdmission = true
+		}
+	}
+
 	createTime := ba.AdmissionHeader.CreateTime
 	if !bypassAdmission && createTime == 0 {
 		// TODO(sumeer): revisit this for multi-tenant. Specifically, the SQL use

pkg/util/admission/work_queue.go

@@ -51,6 +51,16 @@ var KVAdmissionControlEnabled = settings.RegisterBoolSetting(
 	"when true, work performed by the KV layer is subject to admission control",
 	true).WithPublic()
 
+// KVBulkOnlyAdmissionControlEnabled controls whether user (normal and above
+// priority) work is subject to admission control. If it is set to true, then
+// user work will not be throttled by admission control but bulk work still will
+// be.
+var KVBulkOnlyAdmissionControlEnabled = settings.RegisterBoolSetting(
+	settings.SystemOnly,
+	"admission.kv.bulk_only.enabled",
+	"when both admission.kv.enabled and this is true, only throttle bulk work",
+	false).WithPublic()
+
 // SQLKVResponseAdmissionControlEnabled controls whether response processing
 // in SQL, for KV requests, is enabled.
 var SQLKVResponseAdmissionControlEnabled = settings.RegisterBoolSetting(