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Add more comment and clip negative value to prevent Sqrt error

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This commit is contained in:
Chih-Chieh Yang 2022-08-03 15:16:26 +00:00
parent c70ec593ec
commit 3c31efe32f
1 changed files with 16 additions and 2 deletions
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18
test/integration/apiserver/flowcontrol/concurrency_util_test.go
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@ -124,7 +124,10 @@ func (clm *clientLatencyMeasurement) getStats() clientLatencyStats {
defer clm.Mu.Unlock()
mean := clm.Sum / float64(clm.Count)
ss := clm.SumSq - mean*clm.Sum // reduced from ss := sumsq - 2*mean*sum + float64(count)*mean*mean
// Set ss to 0 if negative value is resulted from floating point calculations
if ss < 0 {
ss = 0
}
stdDev := math.Sqrt(ss / float64(clm.Count))
cv := stdDev / mean
return clientLatencyStats{mean: mean, stdDev: stdDev, cv: cv}
@ -141,7 +144,7 @@ type plMetricAvg struct {
seatUtil float64 // average seat utilization
}
func intervalMetricAvg(snapshot0 metricSnapshot, snapshot1 metricSnapshot, plLabel string) plMetricAvg {
func intervalMetricAvg(snapshot0, snapshot1 metricSnapshot, plLabel string) plMetricAvg {
plmT0 := snapshot0[plLabel]
plmT1 := snapshot1[plLabel]
return plMetricAvg{
@ -156,6 +159,17 @@ func intervalMetricAvg(snapshot0 metricSnapshot, snapshot1 metricSnapshot, plLab
// allows to execute at once, while sending fewer than allowed to the other priority level.
// The primary check is that the low flow gets all the seats it wants, but is modulated by
// recognizing that there are uncontrolled overheads in the system.
//
// This test differs from TestPriorityLevelIsolation since TestPriorityLevelIsolation checks throughput instead
// of concurrency. In order to mitigate the effects of system noise, authorization webhook is used to artificially
// increase request execution time to make the system noise relatively insignificant.
//
// Secondarily, this test also checks the observed seat utilizations against values derived from expecting that
// the throughput observed by the client equals the execution throughput observed by the server.
//
// This test recognizes that there is noise in the measurements coming from uncontrolled overheads
// and unsynchronized reading of related quantities. This test takes as a relative error margin 2 times
// the smaller (of the two traffic classes) coefficient of variation of the client-observed latency.
func TestConcurrencyIsolation(t *testing.T) {
defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, genericfeatures.APIPriorityAndFairness, true)()
// NOTE: disabling the feature should fail the test