hipDNN knobs API reference

hipDNN knobs API reference#

2026-03-31

2 min read time

Applies to Linux and Windows

Use this article as a reference for the classes and methods for knobs in hipDNN.

`Knob` class#

Describes metadata for an available knob.

Key methods:

const std::string& knobId(): Get the knob identifier.
const std::string& description(): Get a human-readable description.
bool isDeprecated(): Check if a knob is deprecated.
KnobValueType valueType(): Get value type (INT64, FLOAT64, or STRING).
const KnobValueVariant& defaultValue(): Get the default value as a variant.
const IConstraint* constraint(): Get the constraint validator.
Error validate(const KnobSetting& setting): Validate a setting.

`KnobSetting` class#

Represents a knob value setting to apply.

Constructors:

KnobSetting(std::string knobId, KnobValueVariant value);
template <typename T> KnobSetting(std::string knobId, const T& value);

Key methods:

const std::string& knobId(): Get the knob identifier.
const KnobValueVariant& value(): Get the knob value.
template <typename T> void setValue(const T& value): Update the knob value.

Graph methods#

Querying knobs:

Error get_knobs_for_engine(int64_t engineId, std::vector<Knob>& knobs) const;
Error get_knob_lookup_for_engine(int64_t engineId, std::unordered_map<std::string, Knob>& knobs) const;

Setting knobs:

Error create_execution_plan_ext(int64_t engineId, const std::vector<KnobSetting>& settings);

Constraint classes#

Base interface:

class IConstraint {
    virtual Error validateKnobSetting(const KnobSetting& setting) const = 0;
    virtual std::string toString() const = 0;
};

Implementations:

IntConstraint(int64_t minValue, int64_t maxValue, int64_t step, std::unordered_set<int64_t> validValues)
FloatConstraint(double minValue, double maxValue)
StringConstraint(int32_t maxLength, std::unordered_set<std::string> validValues)
EmptyConstraint(): No constraints

Type definitions#

using KnobValueVariant = std::variant<int64_t, double, std::string>;
typedef std::string KnobType_t;

enum class KnobValueType {
    NOT_SET = 0,
    INT64 = 1,
    FLOAT64 = 2,
    STRING = 3,
};