cluster_linearize::SFLDefaultCostModel

Synopsis

Declared in <cluster_linearize.h>

class SFLDefaultCostModel;

Description

The numbers here were obtained in February 2026 by:

For a variety of machines:
Running a fixed collection of ~385000 clusters found through random generation and fuzzing, optimizing for difficulty of linearization.
Linearize each ~3000 times, with different random seeds. Sometimes without input linearization, sometimes with a bad one.
Gather cycle counts for each of the operations included in this cost model, broken down by their parameters.
Correct the data by subtracting the runtime of obtaining the cycle count.
Drop the 5% top and bottom samples from each cycle count dataset, and compute the average of the remaining samples.
For each operation, fit a least-squares linear function approximation through the samples.
Rescale all machine expressions to make their total time match, as we only care about relative cost of each operation.
Take the per-operation average of operation expressions across all machines, to construct expressions for an average machine.
Approximate the result with integer coefficients. Each cost unit corresponds to somewhere between 0.5 ns and 2.5 ns, depending on the hardware.

Member Functions

Name	Description
`ActivateBegin`	Marks the start of activating a dependency.
`ActivateEnd`	Accounts for the cost of activating a dependency.
`DeactivateBegin`	Marks the start of deactivating a dependency.
`DeactivateEnd`	Accounts for the cost of deactivating a dependency.
`GetCost`	Returns the accumulated cost.
`GetLinearizationBegin`	Marks the start of extracting the linearization.
`GetLinearizationEnd`	Marks the end of extracting the linearization (cost already charged in InitializeEnd).
`InitializeBegin`	Marks the start of the initialization phase.
`InitializeEnd`	Accounts for the cost of initialization and of the final linearization.
`MakeTopologicalBegin`	Marks the start of making the linearization topological.
`MakeTopologicalEnd`	Accounts for the cost of making the linearization topological.
`MergeChunksBegin`	Marks the start of merging chunks.
`MergeChunksEnd`	Accounts for the per-step cost of merging chunks.
`MergeChunksMid`	Accounts for the per-transaction cost of merging chunks.
`MinimizeStepBegin`	Marks the start of a single minimization step.
`MinimizeStepEnd`	Accounts for the cost of finishing a minimization step.
`MinimizeStepMid`	Accounts for the per-transaction cost of a minimization step.
`PickChunkToOptimizeBegin`	Marks the start of picking a chunk to optimize.
`PickChunkToOptimizeEnd`	Accounts for the cost of picking a chunk to optimize.
`PickDependencyToSplitBegin`	Marks the start of picking a dependency to split.
`PickDependencyToSplitEnd`	Accounts for the cost of picking a dependency to split.
`PickMergeCandidateBegin`	Marks the start of picking a merge candidate.
`PickMergeCandidateEnd`	Accounts for the cost of picking a merge candidate.
`StartMinimizingBegin`	Marks the start of a minimization pass.
`StartMinimizingEnd`	Accounts for the cost of starting a minimization pass.
`StartOptimizingBegin`	Marks the start of setting up an optimization round.
`StartOptimizingEnd`	Accounts for the cost of setting up an optimization round.