#include "/Werk/devel/lumi/tests/vault/gear/stress-test-rig.hpp"

Description

template<class CONF>
class vault::gear::test::bench::BreakingPoint< CONF >

Specific stress test scheme to determine the »breaking point« where the Scheduler starts to slip.

Definition at line 268 of file stress-test-rig.hpp.

Classes
struct	Res

Public Member Functions
auto	perform ()
	Launch a measurement sequence to determine the »breaking point« for the configured test load and parametrisation of the Scheduler.

Private Types
using	TestLoad = CONF::TestLoad

using	TestSetup = TestLoad::ScheduleCtx

Private Member Functions
void	configureTest (TestSetup &testSetup, double stressFac)
	prepare the ScheduleCtx for a specifically parametrised test series

Res	runProbes (TestSetup &testSetup, double stressFac)
	perform a repetition of test runs and compute statistics

bool	decideBreakPoint (Res &res)
	criterion to decide if this test series constitutes a slipped schedule

template<class FUN >
Res	conductBinarySearch (FUN &&runTestCase, vector< Res > const &results)
	invoke a binary search to produce a sequence of test series with the goal to narrow down the stressFact where the Schedule slips away.

void	maybeAdaptScaleEmpirically (TestSetup &testSetup, double stressFac)
	Attempt to factor out some observable properties, which are considered circumstantial and not a direct result of scheduling overheads.

void	showRun (uint i, double delta, double t, bool over, bool fail)

void	showStep (Res &res)

void	showRes (Res &res)

void	showRef (TestSetup &testSetup)

Private Attributes
double	adjustmentFac {1.0}
	adaptive scale correction based on observed behaviour

size_t	gaugeProbes = 3 * CONF::REPETITIONS

_Fmt	fmtRun_ {"....·%-2d: Δ=%4.1f t=%4.1f %s %s"}

_Fmt	fmtStep_ { "%4.2f\| : ∅Δ=%4.1f±%-4.2f ∅t=%4.1f %s %%%-3.0f -- expect:%4.1fms"}

_Fmt	fmtResSDv_ {"%9s= %5.2f ±%4.2f%s"}

_Fmt	fmtResVal_ {"%9s: %5.2f%s"}

Class Documentation

◆ vault::gear::test::bench::BreakingPoint::Res

struct vault::gear::test::bench::BreakingPoint::Res

Class Members
double	stressFac {0}
double	percentOff {0}
double	stdDev {0}
double	avgDelta {0}
double	avgTime {0}
double	expTime {0}

Collaboration diagram for BreakingPoint< CONF >::Res:

Member Typedef Documentation

◆ TestLoad

template<class CONF >

using TestLoad = CONF::TestLoad

private

Definition at line 271 of file stress-test-rig.hpp.

◆ TestSetup

template<class CONF >

using TestSetup = TestLoad::ScheduleCtx

private

Definition at line 272 of file stress-test-rig.hpp.

Member Function Documentation

◆ configureTest()

template<class CONF >

void configureTest	(	TestSetup &	testSetup,
		double	stressFac
	)

inlineprivate

prepare the ScheduleCtx for a specifically parametrised test series

Definition at line 286 of file stress-test-rig.hpp.

References BreakingPoint< CONF >::adjustmentFac.

Referenced by BreakingPoint< CONF >::perform().

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◆ runProbes()

template<class CONF >

Res runProbes	(	TestSetup &	testSetup,
		double	stressFac
	)

inlineprivate

perform a repetition of test runs and compute statistics

Definition at line 294 of file stress-test-rig.hpp.

References BreakingPoint< CONF >::maybeAdaptScaleEmpirically(), BreakingPoint< CONF >::showRun(), and BreakingPoint< CONF >::showStep().

Referenced by BreakingPoint< CONF >::perform().

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◆ decideBreakPoint()

template<class CONF >

bool decideBreakPoint ( Res & res )

inlineprivate

criterion to decide if this test series constitutes a slipped schedule

Definition at line 327 of file stress-test-rig.hpp.

References BreakingPoint< CONF >::Res::avgDelta, BreakingPoint< CONF >::Res::percentOff, and BreakingPoint< CONF >::Res::stdDev.

Referenced by BreakingPoint< CONF >::perform(), and BreakingPoint< CONF >::showStep().

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◆ conductBinarySearch()

template<class CONF >

template<class FUN >

Res conductBinarySearch	(	FUN &&	runTestCase,
		vector< Res > const &	results
	)

inlineprivate

invoke a binary search to produce a sequence of test series with the goal to narrow down the stressFact where the Schedule slips away.

Definition at line 341 of file stress-test-rig.hpp.

References BreakingPoint< CONF >::Res::avgDelta, BreakingPoint< CONF >::Res::avgTime, lib::binarySearch_upper(), BreakingPoint< CONF >::Res::expTime, BreakingPoint< CONF >::Res::percentOff, and BreakingPoint< CONF >::Res::stdDev.

Referenced by BreakingPoint< CONF >::perform().

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◆ maybeAdaptScaleEmpirically()

template<class CONF >

void maybeAdaptScaleEmpirically	(	TestSetup &	testSetup,
		double	stressFac
	)

inlineprivate

Attempt to factor out some observable properties, which are considered circumstantial and not a direct result of scheduling overheads.

The artificial computational load is known to drift towards larger values than calibrated; moreover the actual concurrency achieved can deviate from the heuristic assumptions built into the testing schedule. The latter is problematic to some degree however, since the Scheduler is bound to scale down capacity when idle. To strike a reasonable balance, this adjustment of the measurement scale is done only initially, and when the stress factor is high and some degree of pressure on the scheduler can thus be assumed.

Definition at line 385 of file stress-test-rig.hpp.

References BreakingPoint< CONF >::adjustmentFac, BreakingPoint< CONF >::gaugeProbes, and util::limited().

Referenced by BreakingPoint< CONF >::runProbes().

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