step_tuner< check_deps > Struct Template Reference

Default (NOP) implementations of the tuner interface. More...

List of all members.

Public Member Functions
template<typename Tag , typename Arg >
int	priority (const Tag &tag, Arg &arg) const
	Allows defnintion of priorites to individual steps (which are identified by the tag).
template<typename Tag , typename Arg , typename T >
void	depends (const Tag &tag, Arg &arg, T &dC) const
	Allows declaration of data dependencies (to items) of given step (identified by the tag).
bool	preschedule () const
	returns whether the step should be pre-scheduled
template<typename Tag , typename Arg >
int	compute_on (const Tag &, Arg &) const
	tell the scheduler on which process to run the step (or range of steps) (distCnC)
Static Public Attributes
static const bool	check_deps_in_ranges = check_deps

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Detailed Description

template<bool check_deps = true>
struct CnC::step_tuner< check_deps >

Default (NOP) implementations of the tuner interface.

Also defines the interface a user-provided tuner must satisfy. Derive your tuner from this (to avoid implementing the entire interface).

It is recommended that your tuner does not implement the methods as templates. Instead, you should use the actual types that it expects.

#include <cnc/default_tuner.h>

Definition at line 98 of file default_tuner.h.

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Member Function Documentation

int compute_on	(	const Tag &	,
		Arg &
	)		const [inline]

tell the scheduler on which process to run the step (or range of steps) (distCnC)

Returns:

process id where the step will be executed, or COMPUTE_ON_ROUND_ROBIN, or COMPUTE_ON_LOCAL, or COMPUTE_ON_ALL, or COMPUTE_ON_ALL_OTHERS

Definition at line 156 of file default_tuner.h.

        {
            return COMPUTE_ON_ROUND_ROBIN;
        }

void depends	(	const Tag &	tag,
		Arg &	arg,
		T &	dC
	)		const [inline]

Allows declaration of data dependencies (to items) of given step (identified by the tag).

When a step-instance is prescribed through a corresponding tag_collection::put, this method will be called. You can declare dependencies to items by calling dC.depends( item_collection, dependent_item_tag ) for every item the step is going to 'get' in its execute method. The actual step execution will be delayed until all dependencies can be satisfied. The default implementation does nothing (NOP). Your own implementation must accept dC by reference (T&). dC.depends accepts an additional optional argument to declare the process that will produce the item. You can either pass the process-rank or CnC::PRODUCER_UKNOWN or CnC::PRODUCER_LOCAL. This producer argument will have effect only if the tuner of the respective item-collection returns CnC::CONSUMER_UKNOWN, otherwise it will be ignored.

Parameters:

tag	the tag which identifies the step to be executed.
arg	the argument as passed to context< Derived >::prescribed (usually the context)
dC	opaque object (must be by reference!) providing method depends to declare item dependencies

Definition at line 132 of file default_tuner.h.

        {
        }

bool preschedule

(

)

const [inline]

returns whether the step should be pre-scheduled

Pre-scheduling provides an alternative method for detecting data dependencies.

The step instance will be run immediately when prescribed by a tag_collection::put. All items that are not yet available when accessed by the non-blocking get method will automatically be treated as dependent items. The pre-run will end at context::flush_gets() if any items are unavailable. The step execution will be delayed until all detected dependencies can be satisfied.

Definition at line 148 of file default_tuner.h.

        {
            return false;
        }

int priority	(	const Tag &	tag,
		Arg &	arg
	)		const [inline]

Allows defnintion of priorites to individual steps (which are identified by the tag).

Returns:

the default implementation always return 1.

Parameters:

tag	the tag which identifies the step to be executed
arg	the argument as passed to context< Derived >::prescribed (usually the context)

Definition at line 105 of file default_tuner.h.

        {
            return 1;
        }

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Member Data Documentation

const bool check_deps_in_ranges = check_deps [static]

true if steps launched through ranges consume items or need global locking, false otherwise. Avoiding checks for dependencies and global locks saves overhead and will perform better (e.g. for parallel_for). Safe execution (with checks) is the default (check_deps template argument).

Definition at line 164 of file default_tuner.h.

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The documentation for this struct was generated from the following file:

• default_tuner.h