initial design/api for #717

cli/fortio_main.go

@@ -100,6 +100,7 @@ var (
 	qpsFlag         = flag.Float64("qps", defaults.QPS, "Queries Per Seconds or 0 for no wait/max qps")
 	numThreadsFlag  = flag.Int("c", defaults.NumThreads, "Number of connections/goroutine/threads")
 	durationFlag    = flag.Duration("t", defaults.Duration, "How long to run the test or 0 to run until ^C")
+	rampFlag        = flag.Duration("ramp", 0, "Ramp/Warm up time from initial to target QPS")
 	percentilesFlag = flag.String("p", "50,75,90,99,99.9", "List of pXX to calculate")
 	resolutionFlag  = flag.Float64("r", defaults.Resolution, "Resolution of the histogram lowest buckets in seconds")
 	offsetFlag      = flag.Duration("offset", defaults.Offset, "Offset of the histogram data")
@@ -398,6 +399,7 @@ func fortioLoad(justCurl bool, percList []float64, hook bincommon.FortioHook) {
 	ro := periodic.RunnerOptions{
 		QPS:         qps,
 		Duration:    *durationFlag,
+		Ramp:        *rampFlag,
 		NumThreads:  *numThreadsFlag,
 		Percentiles: percList,
 		Resolution:  *resolutionFlag,

periodic/periodic.go

@@ -49,6 +49,8 @@ var DefaultRunnerOptions = RunnerOptions{
 	NumThreads:  4,
 	Percentiles: []float64{90.0},
 	Resolution:  0.001, // milliseconds
+	// Not used unless Ramp is non zero, but if it is:
+	InitialNumThreads: 1,
 }
 
 type ThreadID int
@@ -170,12 +172,21 @@ type RunnerOptions struct {
 	Runners []Runnable `json:"-"`
 	// At which (target) rate to run the Runners across NumThreads.
 	QPS float64
+	// Initial QPS. Used if Ramp duration is specified, will increase the target from InitialQPS to QPS over Ramp duration.
+	InitialQPS float64
+	// Ramp duration. If specified, will increase the target from InitialQPS to QPS over Ramp duration.
+	// default is no ramp up.
+	Ramp time.Duration
 	// How long to run the test for. Unless Exactly is specified.
 	Duration time.Duration
 	// Note that this actually maps to gorountines and not actual threads
 	// but threads seems like a more familiar name to use for non go users
-	// and in a benchmarking context
+	// and in a benchmarking context.
 	NumThreads int
+	// InitialNumThreads is the number of threads to start with when using Ramp.
+	// If Ramp is specified, will increase the number of threads from InitialNumThreads
+	// to NumThreads over Ramp duration.
+	InitialNumThreads int
 	// List of percentiles to calculate.
 	Percentiles []float64
 	// Divider to apply to duration data in seconds. Defaults to 0.001 or 1 millisecond.