starpu-max/doc/doxygen/chapters/api/scheduling_context_hypervisor.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, 2013 Institut National de Recherche en Informatique et Automatique
 * See the file version.doxy for copying conditions.
 */

/*! \defgroup API_Scheduling_Context_Hypervisor Scheduling Context Hypervisor

\struct sc_hypervisor_policy
\ingroup API_Scheduling_Context_Hypervisor
This structure contains all the methods that implement a hypervisor resizing policy.
\var sc_hypervisor_policy::name
        Indicates the name of the policy, if there is not a custom policy, the policy corresponding to this name will be used by the hypervisor
\var sc_hypervisor_policy::custom
        Indicates whether the policy is custom or not
\var sc_hypervisor_policy::size_ctxs
	Distribute workers to contexts even at the begining of the program
\var sc_hypervisor_policy::resize_ctxs
	Require explicit resizing
\var sc_hypervisor_policy::handle_idle_cycle
        It is called whenever the indicated worker executes another idle cycle in sched_ctx
\var sc_hypervisor_policy::handle_pushed_task
        It is called whenever a task is pushed on the worker’s queue corresponding to the context sched_ctx
\var sc_hypervisor_policy::handle_poped_task
        It is called whenever a task is poped from the worker’s queue corresponding to the context sched_ctx
\var sc_hypervisor_policy::handle_poped_task
	The hypervisor takes a decision when another task was poped from this worker in this ctx
\var sc_hypervisor_policy::handle_idle_end
        It is called whenever a task is executed on the indicated worker and context after a long period of idle time
\var sc_hypervisor_policy::handle_post_exec_hook
        It is called whenever a tag task has just been executed. The table of resize requests is provided as well as the tag
\var sc_hypervisor_policy::handle_submitted_job
	The hypervisor takes a decision when a job was submitted in this ctx
\var sc_hypervisor_policy::end_ctx
	The hypervisor takes a decision when a certain ctx was deleted

\struct sc_hypervisor_policy_config
\ingroup API_Scheduling_Context_Hypervisor
This structure contains all configuration information of a
context. It contains configuration information for each context, which
can be used to construct new resize strategies.
\var sc_hypervisor_policy_config::min_nworkers
        Indicates the minimum number of workers needed by the context
\var sc_hypervisor_policy_config::max_nworkers
        Indicates the maximum number of workers needed by the context
\var sc_hypervisor_policy_config::granularity
        Indicates the workers granularity of the context
\var sc_hypervisor_policy_config::priority
        Indicates the priority of each worker in the context
\var sc_hypervisor_policy_config::max_idle
        Indicates the maximum idle time accepted before a resize is triggered
\var sc_hypervisor_policy_config::min_working
	Indicates that underneath this limit the priority of the worker is reduced
\var sc_hypervisor_policy_config::fixed_workers
        Indicates which workers can be moved and which ones are fixed
\var sc_hypervisor_policy_config:: new_workers_max_idle
        Indicates the maximum idle time accepted before a resize is triggered for the workers that just arrived in the new context
\var sc_hypervisor_policy_config::empty_ctx_max_idle
         Indicates that above this context we allow removing all workers
\var sc_hypervisor_policy_config::ispeed_w_sample
         Indicates the sample used to compute the instant speed per worker
\var sc_hypervisor_policy_config::ispeed_ctx_sample
        Indicates the sample used to compute the instant speed per ctxs

\struct sc_hypervisor_wrapper
\ingroup API_Scheduling_Context_Hypervisor
This structure is a wrapper of the contexts available in StarPU
and contains all information about a context obtained by incrementing
the performance counters.
\var sc_hypervisor_wrapper::sched_ctx
        The context wrapped
\var sc_hypervisor_wrapper::config
        The corresponding resize configuration
\var sc_hypervisor_wrapper::current_idle_time
        The idle time counter of each worker of the context
\var sc_hypervisor_wrapper::pushed_tasks
        The number of pushed tasks of each worker of the context
\var sc_hypervisor_wrapper::poped_tasks
        The number of poped tasks of each worker of the context
\var sc_hypervisor_wrapper::total_flops
        The total number of flops to execute by the context
\var sc_hypervisor_wrapper::total_elapsed_flops
        The number of flops executed by each workers of the context
\var sc_hypervisor_wrapper::elapsed_flops
        The number of flops executed by each worker of the context from last resize
\var sc_hypervisor_wrapper::remaining_flops
        The number of flops that still have to be executed by the workers in the context
\var sc_hypervisor_wrapper::start_time
        The time when he started executed
\var sc_hypervisor_wrapper::resize_ack
        The structure confirming the last resize finished and a new one can be done

\struct sc_hypervisor_resize_ack
\ingroup API_Scheduling_Context_Hypervisor
This structures checks if the workers moved to another context
are actually taken into account in that context.
\var sc_hypervisor_resize_ack::receiver_sched_ctx
        The context receiving the new workers
\var sc_hypervisor_resize_ack::moved_workers
        The workers moved to the receiver context
\var sc_hypervisor_resize_ack::nmoved_workers
        The number of workers moved
\var sc_hypervisor_resize_ack::acked_workers
        If the value corresponding to a worker is 1, this one is taken
	into account in the new context if 0 not yet

\struct sc_hypervisor_policy_task_pool
task wrapper linked list
\ingroup API_Scheduling_Context_Hypervisor
\var sc_hypervisor_policy_task_pool::cl
Which codelet has been executed
\var sc_hypervisor_policy_task_pool::footprint
Task footprint key
\var sc_hypervisor_policy_task_pool::sched_ctx_id
Context the task belongs to
\var sc_hypervisor_policy_task_pool::n
Number of tasks of this kind
\var sc_hypervisor_policy_task_pool::next
Other task kinds

\fn void *sc_hypervisor_init(struct sc_hypervisor_policy *policy)
\ingroup API_Scheduling_Context_Hypervisor
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. TODO maybe
they should be hidden to the user

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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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 (needed for Gflops rate based strategy
see \ref ResizingStrategies 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_Scheduling_Context_Hypervisor
Whenever we want to exclude
contexts from the resizing process we have to unregister them from the
hypervisor.

\fn void sc_hypervisor_post_resize_request(unsigned sched_ctx, int task_tag)
\ingroup API_Scheduling_Context_Hypervisor
Requires resizing the context \p sched_ctx whenever a task tagged with the id \p task_tag
finished executing 

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

\fn void sc_hypervisor_stop_resize(unsigned sched_ctx)
\ingroup API_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
Ask the hypervisor to chose a distribution of workers in the required contexts
   
\fn unsigned sc_hypervisor_get_size_req(unsigned **sched_ctxs, int* nsched_ctxs, int **workers, int *nworkers)
\ingroup API_Scheduling_Context_Hypervisor
Check if there are pending demands of resizing

\fn void sc_hypervisor_save_size_req(unsigned *sched_ctxs, int nsched_ctxs, int *workers, int nworkers)
\ingroup API_Scheduling_Context_Hypervisor
Save a demand of resizing

\fn void sc_hypervisor_free_size_req(void)
\ingroup API_Scheduling_Context_Hypervisor
Clear the list of pending demands of resizing

\fn unsigned sc_hypervisor_can_resize(unsigned sched_ctx)
\ingroup API_Scheduling_Context_Hypervisor
Check out if a context can be resized

\fn void sc_hypervisor_set_type_of_task(struct starpu_codelet *cl, unsigned sched_ctx, uint32_t footprint, size_t data_size)
\ingroup API_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
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_Scheduling_Context_Hypervisor
This macro is used when calling sc_hypervisor_ctl() and must be
followed by 1 arguments


\fn struct sc_hypervisor_policy_config *sc_hypervisor_get_config(unsigned sched_ctx);
\ingroup API_Scheduling_Context_Hypervisor
Returns the configuration structure of a context

\fn void sc_hypervisor_set_config(unsigned sched_ctx, void *config);
\ingroup API_Scheduling_Context_Hypervisor
Set a certain configuration to a contexts

\fn int *sc_hypervisor_get_sched_ctxs();
\ingroup API_Scheduling_Context_Hypervisor
    Gets the contexts managed by the hypervisor

\fn int sc_hypervisor_get_nsched_ctxs();
\ingroup API_Scheduling_Context_Hypervisor
    Gets the number of contexts managed by the hypervisor

\fn struct sc_hypervisor_wrapper *sc_hypervisor_get_wrapper(unsigned sched_ctx);
\ingroup API_Scheduling_Context_Hypervisor
    Returns the wrapper corresponding the context \p sched_ctx

\fn double sc_hypervisor_get_elapsed_flops_per_sched_ctx(struct sc_hypervisor_wrapper *sc_w);
\ingroup API_Scheduling_Context_Hypervisor
    Returns the flops of a context elapsed from the last resize


*/