/*
 * This file is part of the StarPU Handbook.
 * Copyright (C) 2009--2011  Universit@'e de Bordeaux
 * Copyright (C) 2010, 2011, 2012, 2013, 2014  CNRS
 * Copyright (C) 2011, 2012, 2013 INRIA
 * See the file version.doxy for copying conditions.
 */

/*! \defgroup API_SC_Hypervisor_usage Scheduling Context Hypervisor - Regular usage

\fn void *sc_hypervisor_init(struct sc_hypervisor_policy *policy)
\ingroup API_SC_Hypervisor_usage
There is a single hypervisor that is in charge of resizing contexts
and the resizing strategy is chosen at the initialization of the
hypervisor. A single resize can be done at a time.

The Scheduling Context Hypervisor Plugin provides a series of
performance counters to StarPU. By incrementing them, StarPU can help
the hypervisor in the resizing decision making process.

This function initializes the hypervisor to use the strategy provided as parameter
and creates the performance counters (see starpu_sched_ctx_performance_counters).
These performance counters represent actually some callbacks that will
be used by the contexts to notify the information needed by the
hypervisor.

Note: The Hypervisor is actually a worker that takes this role once
certain conditions trigger the resizing process (there is no
additional thread assigned to the hypervisor).

\fn void sc_hypervisor_shutdown(void)
\ingroup API_SC_Hypervisor_usage
The hypervisor and all information concerning it is cleaned. There is
no synchronization between this function and starpu_shutdown(). Thus,
this should be called after starpu_shutdown(), because the performance
counters will still need allocated callback functions.

\fn void sc_hypervisor_register_ctx(unsigned sched_ctx, double total_flops)
\ingroup API_SC_Hypervisor_usage
Scheduling Contexts that have to be resized by the hypervisor must be
first registered to the hypervisor. 
This function registers the context to the hypervisor, and indicate the number of
flops the context will execute (used for Gflops rate based strategy
or any other custom strategy needing it, for the others we can pass 0.0)

\fn void sc_hypervisor_unregister_ctx(unsigned sched_ctx)
\ingroup API_SC_Hypervisor_usage
Whenever we want to exclude
contexts from the resizing process we have to unregister them from the
hypervisor.

\fn void sc_hypervisor_resize_ctxs(unsigned *sched_ctxs, int nsched_ctxs , int *workers, int nworkers)
\ingroup API_SC_Hypervisor_usage
Requires reconsidering the distribution of ressources over the indicated scheduling contexts 

\fn void sc_hypervisor_stop_resize(unsigned sched_ctx)
\ingroup API_SC_Hypervisor_usage
The user can totally forbid the resizing of a certain context or can
then change his mind and allow it (in this case the resizing is
managed by the hypervisor, that can forbid it or allow it)

\fn void sc_hypervisor_start_resize(unsigned sched_ctx)
\ingroup API_SC_Hypervisor_usage
Allow resizing of a context. The user can then provide information to
the hypervisor concerning the conditions of resizing.

\fn char *sc_hypervisor_get_policy();
\ingroup API_SC_Hypervisor_usage
Returns the name of the resizing policy the hypervisor uses

\fn void sc_hypervisor_add_workers_to_sched_ctx(int* workers_to_add, unsigned nworkers_to_add, unsigned sched_ctx)
\ingroup API_SC_Hypervisor_usage
Ask the hypervisor to add workers to a sched_ctx 

\fn void sc_hypervisor_remove_workers_from_sched_ctx(int* workers_to_remove, unsigned nworkers_to_remove, unsigned sched_ctx, unsigned now)
\ingroup API_SC_Hypervisor_usage
Ask the hypervisor to remove workers from a sched_ctx 

\fn void sc_hypervisor_move_workers(unsigned sender_sched_ctx, unsigned receiver_sched_ctx, int *workers_to_move, unsigned nworkers_to_move, unsigned now)
\ingroup API_SC_Hypervisor_usage
Moves workers from one context to another
   
\fn void sc_hypervisor_size_ctxs(unsigned *sched_ctxs, int nsched_ctxs, int *workers, int nworkers)
\ingroup API_SC_Hypervisor_usage
Ask the hypervisor to chose a distribution of workers in the required contexts
   

\fn void sc_hypervisor_set_type_of_task(struct starpu_codelet *cl, unsigned sched_ctx, uint32_t footprint, size_t data_size)
\ingroup API_SC_Hypervisor_usage
Indicate the types of tasks a context will execute in order to better decide the sizing of ctxs

\fn void sc_hypervisor_update_diff_total_flops(unsigned sched_ctx, double diff_total_flops)
\ingroup API_SC_Hypervisor_usage
Change dynamically the total number of flops of a context, move the deadline of the finishing time of the context

\fn void sc_hypervisor_update_diff_elapsed_flops(unsigned sched_ctx, double diff_task_flops)
\ingroup API_SC_Hypervisor_usage
Change dynamically the number of the elapsed flops in a context, modify the past in order to better compute the speed 

\fn void sc_hypervisor_ctl(unsigned sched_ctx, ...)
\ingroup API_SC_Hypervisor_usage
Inputs conditions to the context sched_ctx with the following
arguments. The argument list must be zero-terminated.

\def SC_HYPERVISOR_MAX_IDLE
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 3 arguments: an array of int for the workerids to apply
the condition, an int to indicate the size of the array, and a double
value indicating the maximum idle time allowed for a worker before the
resizing process should be triggered

\def SC_HYPERVISOR_PRIORITY
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 3 arguments: an array of int for the workerids to apply
the condition, an int to indicate the size of the array, and an int
value indicating the priority of the workers previously mentioned. The
workers with the smallest priority are moved the first.

\def SC_HYPERVISOR_MIN_WORKERS
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument(int) indicating the minimum number of workers a
context should have, underneath this limit the context cannot execute.

\def SC_HYPERVISOR_MAX_WORKERS
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument(int) indicating the maximum number of workers a
context should have, above this limit the context would not be able to
scale

\def SC_HYPERVISOR_GRANULARITY
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument(int) indicating the granularity of the resizing
process (the number of workers should be moved from the context once
it is resized) This parameter is ignore for the Gflops rate based
strategy (see \ref ResizingStrategies), the number of workers that have to
be moved is calculated by the strategy.

\def SC_HYPERVISOR_FIXED_WORKERS
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 2 arguments: an array of int for the workerids to apply
the condition and an int to indicate the size of the array. These
workers are not allowed to be moved from the context.

\def SC_HYPERVISOR_MIN_TASKS
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument (int) that indicated the minimum number of
tasks that have to be executed before the context could be resized.
This parameter is ignored for the Application Driven strategy (see \ref 
ResizingStrategies) where the user indicates exactly when the resize
should be done.

\def SC_HYPERVISOR_NEW_WORKERS_MAX_IDLE
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument, a double value indicating the maximum idle
time allowed for workers that have just been moved from other contexts
in the current context.

\def SC_HYPERVISOR_TIME_TO_APPLY
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument (int) indicating the tag an executed task
should have such that this configuration should be taken into account.


\def SC_HYPERVISOR_ISPEED_W_SAMPLE
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument, a double, that indicates the number of flops
needed to be executed before computing the speed of a worker

\def SC_HYPERVISOR_ISPEED_CTX_SAMPLE
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 argument, a double, that indicates the number of flops
needed to be executed before computing the speed of a context


\def SC_HYPERVISOR_NULL
\ingroup API_SC_Hypervisor_usage
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 arguments

*/
