/* * This file is part of the StarPU Handbook. * Copyright (C) 2009--2011 Universit@'e de Bordeaux * Copyright (C) 2010, 2011, 2012, 2013, 2014 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_Policy Scheduling Policy \brief TODO. While StarPU comes with a variety of scheduling policies (see \ref TaskSchedulingPolicy), it may sometimes be desirable to implement custom policies to address specific problems. The API described below allows users to write their own scheduling policy. \struct starpu_sched_policy \ingroup API_Scheduling_Policy This structure contains all the methods that implement a scheduling policy. An application may specify which scheduling strategy in the field starpu_conf::sched_policy passed to the function starpu_init(). \var void (*starpu_sched_policy::init_sched)(unsigned sched_ctx_id) Initialize the scheduling policy. \var void (*starpu_sched_policy::deinit_sched)(unsigned sched_ctx_id) Cleanup the scheduling policy. \var int (*starpu_sched_policy::push_task)(struct starpu_task *) Insert a task into the scheduler. \var void (*starpu_sched_policy::push_task_notify)(struct starpu_task *, int workerid, int perf_workerid, unsigned sched_ctx_id) Notify the scheduler that a task was pushed on a given worker. This method is called when a task that was explicitly assigned to a worker becomes ready and is about to be executed by the worker. This method therefore permits to keep the state of the scheduler coherent even when StarPU bypasses the scheduling strategy. \var struct starpu_task *(*starpu_sched_policy::pop_task)(unsigned sched_ctx_id) Get a task from the scheduler. The mutex associated to the worker is already taken when this method is called. If this method is defined as NULL, the worker will only execute tasks from its local queue. In this case, the push_task method should use the starpu_push_local_task method to assign tasks to the different workers. \var struct starpu_task *(*starpu_sched_policy::pop_every_task)(unsigned sched_ctx_id) Remove all available tasks from the scheduler (tasks are chained by the means of the field starpu_task::prev and starpu_task::next). The mutex associated to the worker is already taken when this method is called. This is currently not used. \var void (*starpu_sched_policy::pre_exec_hook)(struct starpu_task *) Optional field. This method is called every time a task is starting. \var void (*starpu_sched_policy::post_exec_hook)(struct starpu_task *) Optional field. This method is called every time a task has been executed. \var void (*starpu_sched_policy::add_workers)(unsigned sched_ctx_id, int *workerids, unsigned nworkers) Initialize scheduling structures corresponding to each worker used by the policy. \var void (*starpu_sched_policy::remove_workers)(unsigned sched_ctx_id, int *workerids, unsigned nworkers) Deinitialize scheduling structures corresponding to each worker used by the policy. \var const char *starpu_sched_policy::policy_name Optional field. Name of the policy. \var const char *starpu_sched_policy::policy_description Optional field. Human readable description of the policy. \fn struct starpu_sched_policy **starpu_sched_get_predefined_policies() \ingroup API_Scheduling_Policy Return an NULL-terminated array of all the predefined scheduling policies. \fn void starpu_worker_get_sched_condition(int workerid, starpu_pthread_mutex_t **sched_mutex, starpu_pthread_cond_t **sched_cond) \ingroup API_Scheduling_Policy When there is no available task for a worker, StarPU blocks this worker on a condition variable. This function specifies which condition variable (and the associated mutex) should be used to block (and to wake up) a worker. Note that multiple workers may use the same condition variable. For instance, in the case of a scheduling strategy with a single task queue, the same condition variable would be used to block and wake up all workers. \fn int starpu_sched_set_min_priority(int min_prio) \ingroup API_Scheduling_Policy TODO: check if this is correct Defines the minimum task priority level supported by the scheduling policy. 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_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_set_max_priority(int max_prio) \ingroup API_Scheduling_Policy TODO: check if this is correct Defines the maximum priority level supported by the scheduling policy. The default maximum priority level is 1. The application may access that value by calling the function starpu_sched_get_max_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_get_min_priority(void) \ingroup API_Scheduling_Policy TODO: check if this is correct Returns the current minimum priority level supported by the scheduling policy \fn int starpu_sched_get_max_priority(void) \ingroup API_Scheduling_Policy TODO: check if this is correct Returns the current maximum priority level supported by the scheduling policy \fn int starpu_push_local_task(int workerid, struct starpu_task *task, int back) \ingroup API_Scheduling_Policy The scheduling policy may put tasks directly into a worker’s local queue so that it is not always necessary to create its own queue when the local queue is sufficient. If \p back is not 0, \p task is put at the back of the queue where the worker will pop tasks first. Setting \p back to 0 therefore ensures a FIFO ordering. \fn int starpu_push_task_end(struct starpu_task *task) \ingroup API_Scheduling_Policy This function must be called by a scheduler to notify that the given task has just been pushed. \fn int starpu_worker_can_execute_task(unsigned workerid, struct starpu_task *task, unsigned nimpl) \ingroup API_Scheduling_Policy Check if the worker specified by workerid can execute the codelet. Schedulers need to call it before assigning a task to a worker, otherwise the task may fail to execute. \fn int starpu_worker_can_execute_task_impl(unsigned workerid, struct starpu_task *task, unsigned *impl_mask) \ingroup API_Scheduling_Policy Check if the worker specified by workerid can execute the codelet and returns which implementation numbers can be used. Schedulers need to call it before assigning a task to a worker, otherwise the task may fail to execute. This should be preferred rather than calling starpu_worker_can_execute_task for each and every implementation. It can also be used with impl_mask == NULL to check for at least one implementation without determining which. \fn int starpu_worker_can_execute_task_first_impl(unsigned workerid, struct starpu_task *task, unsigned *nimpl) \ingroup API_Scheduling_Policy Check if the worker specified by workerid can execute the codelet and returns the first implementation which can be used. Schedulers need to call it before assigning a task to a worker, otherwise the task may fail to execute. This should be preferred rather than calling starpu_worker_can_execute_task for each and every implementation. It can also be used with impl_mask == NULL to check for at least one implementation without determining which. \fn uint32_t starpu_task_footprint(struct starpu_perfmodel *model, struct starpu_task *task, struct starpu_perfmodel_arch *arch, unsigned nimpl) \ingroup API_Scheduling_Policy Returns the footprint for a given task, taking into account user-provided perfmodel footprint or size_base functions. \fn uint32_t starpu_task_data_footprint(struct starpu_task *task) \ingroup API_Scheduling_Policy Returns the raw footprint for the data of a given task (without taking into account user-provided functions). \fn double starpu_task_expected_length(struct starpu_task *task, struct starpu_perfmodel_arch *arch, unsigned nimpl) \ingroup API_Scheduling_Policy Returns expected task duration in micro-seconds. \fn double starpu_worker_get_relative_speedup(struct starpu_perfmodel_arch *perf_arch) \ingroup API_Scheduling_Policy Returns an estimated speedup factor relative to CPU speed \fn double starpu_task_expected_data_transfer_time(unsigned memory_node, struct starpu_task *task) \ingroup API_Scheduling_Policy Returns expected data transfer time in micro-seconds. \fn double starpu_data_expected_transfer_time(starpu_data_handle_t handle, unsigned memory_node, enum starpu_data_access_mode mode) \ingroup API_Scheduling_Policy Predict the transfer time (in micro-seconds) to move \p handle to a memory node \fn double starpu_task_expected_power(struct starpu_task *task, struct starpu_perfmodel_arch *arch, unsigned nimpl) \ingroup API_Scheduling_Policy Returns expected power consumption in J \fn double starpu_task_expected_conversion_time(struct starpu_task *task, struct starpu_perfmodel_arch *arch, unsigned nimpl) \ingroup API_Scheduling_Policy Returns expected conversion time in ms (multiformat interface only) \fn int starpu_get_prefetch_flag(void) \ingroup API_Scheduling_Policy Whether \ref STARPU_PREFETCH was set \fn int starpu_prefetch_task_input_on_node(struct starpu_task *task, unsigned node) \ingroup API_Scheduling_Policy Prefetch data for a given task on a given node \fn int starpu_idle_prefetch_task_input_on_node(struct starpu_task *task, unsigned node) \ingroup API_Scheduling_Policy Prefetch data for a given task on a given node when the bus is idle \fn void starpu_sched_ctx_worker_shares_tasks_lists(int workerid, int sched_ctx_id) \ingroup API_Scheduling_Policy The scheduling policies indicates if the worker may pop tasks from the list of other workers or if there is a central list with task for all the workers */