starpu-max/doc/doxygen/chapters/api/scheduling_contexts.doxy

/*
 * This file is part of the StarPU Handbook.
 * Copyright (C) 2009--2011  Universit@'e de Bordeaux 1
 * Copyright (C) 2010, 2011, 2012, 2013  Centre National de la Recherche Scientifique
 * Copyright (C) 2011, 2012 Institut National de Recherche en Informatique et Automatique
 * See the file version.doxy for copying conditions.
 */

/*! \defgroup API_Scheduling_Contexts Scheduling Contexts

\brief StarPU permits on one hand grouping workers in combined workers
in order to execute a parallel task and on the other hand grouping
tasks in bundles that will be executed by a single specified worker.
In contrast when we group workers in scheduling contexts we submit
starpu tasks to them and we schedule them with the policy assigned to
the context. Scheduling contexts can be created, deleted and modified
dynamically.

\enum starpu_worker_collection_type
\ingroup API_Scheduling_Contexts
types of structures the worker collection can implement
\var starpu_worker_collection_type::STARPU_WORKER_LIST
\ingroup API_Scheduling_Contexts
List of workers

\struct starpu_sched_ctx_iterator
\ingroup API_Scheduling_Contexts
todo
\var starpu_sched_ctx_iterator::cursor
todo

\struct starpu_worker_collection
\ingroup API_Scheduling_Contexts
A scheduling context manages a collection of workers that can
be memorized using different data structures. Thus, a generic
structure is available in order to simplify the choice of its type.
Only the list data structure is available but further data
structures(like tree) implementations are foreseen.
\var starpu_worker_collection::workerids
        The workerids managed by the collection
\var starpu_worker_collection::nworkers
        The number of workers in the collection
\var starpu_worker_collection::type
        The type of structure (currently ::STARPU_WORKER_LIST is the only one available)
\var starpu_worker_collection::has_next
        Checks if there is another element in collection
\var starpu_worker_collection::get_next
        return the next element in the collection
\var starpu_worker_collection::add
        add a new element in the collection
\var starpu_worker_collection::remove
        remove an element from the collection
\var starpu_worker_collection::init
        Initialize the collection
\var starpu_worker_collection::deinit
        Deinitialize the colection
\var starpu_worker_collection::init_iterator
        Initialize the cursor if there is one

\struct starpu_sched_ctx_performance_counters
Performance counters used by the starpu to indicate the
hypervisor how the application and the resources are executing.
\ingroup API_Scheduling_Contexts
\var starpu_sched_ctx_performance_counters::notify_idle_cycle
        Informs the hypervisor for how long a worker has been idle in the specified context
\var starpu_sched_ctx_performance_counters::notify_idle_end
        Informs the hypervisor that after a period of idle, the worker has just executed a task in the specified context. The idle counter it though reset.
\var starpu_sched_ctx_performance_counters::notify_pushed_task
        Notifies the hypervisor a task has been scheduled on the queue of the worker corresponding to the specified context
\var starpu_sched_ctx_performance_counters::notify_poped_task
        Informs the hypervisor a task executing a specified number of instructions has been poped from the worker
\var starpu_sched_ctx_performance_counters::notify_post_exec_hook
        Notifies the hypervisor a task has just been executed

@name Scheduling Contexts Basic API
\ingroup API_Scheduling_Contexts

\fn unsigned starpu_sched_ctx_create(const char *policy_name, int *workerids_ctx, int nworkers_ctx, const char *sched_ctx_name)
\ingroup API_Scheduling_Contexts
This function creates a scheduling context which uses the scheduling
policy \p policy_name and assigns the workers in \p workerids_ctx to
execute the tasks submitted to it.
The return value represents the identifier of the context that has
just been created. It will be further used to indicate the context the
tasks will be submitted to. The return value should be at most
\ref STARPU_NMAX_SCHED_CTXS.

\fn unsigned starpu_sched_ctx_create_with_custom_policy(struct starpu_sched_policy *policy, int *workerids_ctx, int nworkers_ctx, const char *sched_ctx_name)
\ingroup API_Scheduling_Contexts
This function creates a scheduling context which uses the scheduling
policy \p policy (the pointer to the custom scheduling policy) and assigns the workers in \p workerids_ctx to
execute the tasks submitted to it.
The return value represents the identifier of the context that has
just been created. It will be further used to indicate the context the
tasks will be submitted to. The return value should be at most
\ref STARPU_NMAX_SCHED_CTXS.

\fn unsigned starpu_sched_ctx_create_inside_interval(const char *policy_name, const char *sched_name, int min_ncpus, int max_ncpus, int min_ngpus, int max_ngpus, unsigned allow_overlap)
\ingroup API_Scheduling_Contexts
Create a context indicating an approximate interval of resources

\fn void starpu_sched_ctx_delete(unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Delete scheduling context \p sched_ctx_id and transfer remaining
workers to the inheritor scheduling context.

\fn void starpu_sched_ctx_add_workers(int *workerids_ctx, int nworkers_ctx, unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
This function adds dynamically the workers in \p workerids_ctx to the
context \p sched_ctx_id. The last argument cannot be greater than
\ref STARPU_NMAX_SCHED_CTXS.

\fn void starpu_sched_ctx_remove_workers(int *workerids_ctx, int nworkers_ctx, unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
This function removes the workers in \p workerids_ctx from the context
\p sched_ctx_id. The last argument cannot be greater than
STARPU_NMAX_SCHED_CTXS.

\fn void starpu_sched_ctx_set_inheritor(unsigned sched_ctx_id, unsigned inheritor)
\ingroup API_Scheduling_Contexts
Indicate which context whill inherit the resources of this context
when he will be deleted.

\fn void starpu_sched_ctx_set_context(unsigned *sched_ctx_id)
\ingroup API_Scheduling_Contexts
Set the scheduling context the subsequent tasks will be submitted to

\fn unsigned starpu_sched_ctx_get_context(void)
\ingroup API_Scheduling_Contexts
Return the scheduling context the tasks are currently submitted to

\fn void starpu_sched_ctx_stop_task_submission(void)
\ingroup API_Scheduling_Contexts
Stop submitting tasks from the empty context list until the next time
the context has time to check the empty context list

\fn void starpu_sched_ctx_finished_submit(unsigned sched_ctx_id);
\ingroup API_Scheduling_Contexts
Indicate starpu that the application finished submitting to this
context in order to move the workers to the inheritor as soon as
possible.

\fn unsigned starpu_sched_ctx_get_nworkers(unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Return the number of workers managed by the specified contexts
(Usually needed to verify if it manages any workers or if it should be
blocked)

\fn unsigned starpu_sched_ctx_get_nshared_workers(unsigned sched_ctx_id, unsigned sched_ctx_id2)
\ingroup API_Scheduling_Contexts
    Return the number of workers shared by two contexts.

\fn unsigned starpu_sched_ctx_contains_worker(int workerid, unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Return 1 if the worker belongs to the context and 0 otherwise

\fn unsigned starpu_sched_ctx_overlapping_ctxs_on_worker(int workerid)
\ingroup API_Scheduling_Contexts
Check if a worker is shared between several contexts

\fn unsigned starpu_sched_ctx_is_ctxs_turn(int workerid, unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Manage sharing of resources between contexts: checkOB which ctx has
its turn to pop.

\fn void starpu_sched_ctx_set_turn_to_other_ctx(int workerid, unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Manage sharing of resources between contexts: by default a round_robin
strategy is executed but the user can interfere to tell which ctx has
its turn to pop.

@name Scheduling Context Priorities
\ingroup API_Scheduling_Contexts

\def STARPU_MIN_PRIO
\ingroup API_Scheduling_Contexts
Provided for legacy reasons.

\def STARPU_MAX_PRIO
\ingroup API_Scheduling_Contexts
Provided for legacy reasons.

\def STARPU_DEFAULT_PRIO
\ingroup API_Scheduling_Contexts
By convention, the default priority level should be 0 so that we can
statically allocate tasks with a default priority.

\fn int starpu_sched_ctx_set_min_priority(unsigned sched_ctx_id, int min_prio)
\ingroup API_Scheduling_Contexts
Defines the minimum task priority level supported by the scheduling
policy of the given scheduler context. The default minimum priority
level is the same as the default priority level which is 0 by
convention. The application may access that value by calling the function
starpu_sched_ctx_get_min_priority(). This function should only
be called from the initialization method of the scheduling policy, and
should not be used directly from the application.

\fn int starpu_sched_ctx_set_max_priority(unsigned sched_ctx_id, int max_prio)
\ingroup API_Scheduling_Contexts
Defines the maximum priority level supported by the scheduling policy
of the given scheduler context. The default maximum priority level is
1. The application may access that value by calling the
starpu_sched_ctx_get_max_priority function. This function should only
be called from the initialization method of the scheduling policy, and
should not be used directly from the application.

\fn int starpu_sched_ctx_get_min_priority(unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Returns the current minimum priority level supported by the scheduling
policy of the given scheduler context.

\fn int starpu_sched_ctx_get_max_priority(unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Returns the current maximum priority level supported by the scheduling
policy of the given scheduler context.

@name Scheduling Context Worker Collection
\ingroup API_Scheduling_Contexts

\fn struct starpu_worker_collection *starpu_sched_ctx_create_worker_collection(unsigned sched_ctx_id, enum starpu_worker_collection_type type)
\ingroup API_Scheduling_Contexts
Create a worker collection of the type indicated by the last parameter
for the context specified through the first parameter.

\fn void starpu_sched_ctx_delete_worker_collection(unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Delete the worker collection of the specified scheduling context

\fn struct starpu_worker_collection *starpu_sched_ctx_get_worker_collection(unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Return the worker collection managed by the indicated context

\fn unsigned starpu_sched_ctx_get_workers_list(unsigned sched_ctx_id, int **workerids)
\ingroup API_Scheduling_Contexts
Returns the list of workers in the array \p workerids, the returned value is the 
number of workers. The user should free the \p workerids table after finishing
using it (it is allocated inside the function with the proper size)

@name Scheduling Context Link with Hypervisor
\ingroup API_Scheduling_Contexts

\fn void starpu_sched_ctx_set_perf_counters(unsigned sched_ctx_id, struct starpu_sched_ctx_performance_counters *perf_counters)
\ingroup API_Scheduling_Contexts
Indicates to starpu the pointer to the performance counter

\fn void starpu_sched_ctx_call_pushed_task_cb(int workerid, unsigned sched_ctx_id)
\ingroup API_Scheduling_Contexts
Callback that lets the scheduling policy tell the hypervisor that a
task was pushed on a worker

\fn void starpu_sched_ctx_notify_hypervisor_exists(void)
\ingroup API_Scheduling_Contexts
Allow the hypervisor to let starpu know he's initialised

\fn unsigned starpu_sched_ctx_check_if_hypervisor_exists(void)
\ingroup API_Scheduling_Contexts
Ask starpu if he is informed if the hypervisor is initialised

*/