wip - write amp accounting

pkg/kv/kvserver/kvadmission/kvadmission.go

@@ -106,6 +106,15 @@ var ProvisionedBandwidth = settings.RegisterByteSizeSetting(
 	0,
 	settings.WithPublic)
 
+// ElasticBandwidthMaxUtil sets the max utilization for disk bandwidth for elastic traffic.
+var ElasticBandwidthMaxUtil = settings.RegisterFloatSetting(
+	settings.SystemOnly, "kvadmission.store.elastic_disk_bandwidth_max_util",
+	"sets the max utilization for disk bandwidth for elastic traffic",
+	0.9,
+	settings.NonNegativeFloatWithMaximum(1.0),
+	settings.FloatWithMinimum(0.05),
+)
+
 // FlowTokenDropInterval determines the frequency at which we check for pending
 // flow token dispatches to nodes we're no longer connected to, in order to drop
 // them.

pkg/util/admission/admission.go

@@ -276,11 +276,14 @@ type granterWithIOTokens interface {
 	setAvailableTokens(
 		ioTokens int64, elasticIOTokens int64, elasticDiskBandwidthTokens int64,
 		ioTokensCapacity int64, elasticIOTokenCapacity int64, elasticDiskBandwidthTokensCapacity int64,
-		lastTick bool,
+		estimatedWriteAmp float64, lastTick bool,
 	) (tokensUsed int64, tokensUsedByElasticWork int64)
-	// getDiskTokensUsedAndReset returns the disk bandwidth tokens used
-	// since the last such call.
-	getDiskTokensUsedAndReset() [admissionpb.NumWorkClasses]int64
+	// getDiskTokensUsedAndReset returns the disk bandwidth tokens actually used
+	// and the tokens requested since the last such call.
+	getDiskTokensUsedAndReset() (
+		requestedTokens [admissionpb.NumWorkClasses]diskTokens,
+		usedTokens [admissionpb.NumWorkClasses]diskTokens,
+	)
 	// setLinearModels supplies the models to use when storeWriteDone or
 	// storeReplicatedWorkAdmittedLocked is called, to adjust token consumption.
 	// Note that these models are not used for token adjustment at admission