starpu-max/src/datawizard/coherency.h

/* StarPU --- Runtime system for heterogeneous multicore architectures.
 *
 * Copyright (C) 2009-2015  Université de Bordeaux
 * Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015  CNRS
 * Copyright (C) 2014-2015  Inria
 *
 * StarPU is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at
 * your option) any later version.
 *
 * StarPU is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * See the GNU Lesser General Public License in COPYING.LGPL for more details.
 */

#ifndef __COHERENCY__H__
#define __COHERENCY__H__

#include <starpu.h>
#include <common/config.h>

#include <common/starpu_spinlock.h>
#include <common/rwlock.h>
#include <common/timing.h>
#include <common/fxt.h>
#include <common/list.h>

#include <datawizard/interfaces/data_interface.h>
#include <datawizard/datastats.h>
#include <datawizard/memstats.h>
#include <datawizard/data_request.h>

enum _starpu_cache_state
{
	STARPU_OWNER,
	STARPU_SHARED,
	STARPU_INVALID
};

/* this should contain the information relative to a given data replicate  */
struct _starpu_data_replicate
{
	starpu_data_handle_t handle;

	/* describe the actual data layout, as manipulated by data interfaces in *_interface.c */
	void *data_interface;

	unsigned memory_node;

	/* describes the state of the local data in term of coherency */
	enum _starpu_cache_state	state;

	/* How many requests or tasks are currently working with this replicate */
	int refcnt;

	/* A buffer that is used for SCRATCH or reduction cannnot be used with
	 * filters. */
	unsigned relaxed_coherency:2;

	/* We may need to initialize the replicate with some value before using it. */
	unsigned initialized:1;

	/* is the data locally allocated ? */
	unsigned allocated:1;
	/* was it automatically allocated ? (else it's the application-provided
	 * buffer, don't ever try to free it!) */
	/* perhaps the allocation was perform higher in the hiearchy
	 * for now this is just translated into !automatically_allocated
	 * */
	unsigned automatically_allocated:1;

        /* Pointer to memchunk for LRU strategy */
	struct _starpu_mem_chunk * mc;

	/* To help the scheduling policies to make some decision, we
	   may keep a track of the tasks that are likely to request
	   this data on the current node.
	   It is the responsability of the scheduling _policy_ to set that
	   flag when it assigns a task to a queue, policies which do not
	   use this hint can simply ignore it.
	 */
	uint32_t requested;
	struct _starpu_data_request *request[STARPU_MAXNODES];
};

struct _starpu_data_requester_list;

struct _starpu_jobid_list
{
	unsigned long id;
	struct _starpu_jobid_list *next;
};

/* This structure describes a simply-linked list of task */
struct _starpu_task_wrapper_list
{
	struct starpu_task *task;
	struct _starpu_task_wrapper_list *next;
};

/* This structure describes a doubly-linked list of task */
struct _starpu_task_wrapper_dlist
{
	struct starpu_task *task;
	struct _starpu_task_wrapper_dlist *next;
	struct _starpu_task_wrapper_dlist *prev;
};

extern int _starpu_has_not_important_data;

typedef void (*_starpu_data_handle_unregister_hook)(starpu_data_handle_t);

struct _starpu_data_state
{
	struct _starpu_data_requester_list req_list;
	/* the number of requests currently in the scheduling engine (not in
	 * the req_list anymore), i.e. the number of holders of the
	 * current_mode rwlock */
	unsigned refcnt;
	/* Current access mode. Is always either STARPU_R, STARPU_W,
	 * STARPU_SCRATCH or STARPU_REDUX, but never a combination such as
	 * STARPU_RW. */
	enum starpu_data_access_mode current_mode;
	/* protect meta data */
	struct _starpu_spinlock header_lock;

	/* Condition to make application wait for all transfers before freeing handle */
	/* busy_count is the number of handle->refcnt, handle->per_node[*]->refcnt, number of starpu_data_requesters, and number of tasks that have released it but are still registered on the implicit data dependency lists. */
	/* Core code which releases busy_count has to call
	 * _starpu_data_check_not_busy to let starpu_data_unregister proceed */
	unsigned busy_count;
	/* Is starpu_data_unregister waiting for busy_count? */
	unsigned busy_waiting;
	starpu_pthread_mutex_t busy_mutex;
	starpu_pthread_cond_t busy_cond;

	/* In case we user filters, the handle may describe a sub-data */
	struct _starpu_data_state *root_handle; /* root of the tree */
	struct _starpu_data_state *father_handle; /* father of the node, NULL if the current node is the root */
	unsigned sibling_index; /* indicate which child this node is from the father's perpsective (if any) */
	unsigned depth; /* what's the depth of the tree ? */

	starpu_data_handle_t children;
	unsigned nchildren;

	/* describe the state of the data in term of coherency */
	struct _starpu_data_replicate per_node[STARPU_MAXNODES];
	struct _starpu_data_replicate per_worker[STARPU_NMAXWORKERS];

	struct starpu_data_interface_ops *ops;

	/* Footprint which identifies data layout */
	uint32_t footprint;

	/* where is the data home, i.e. which node it was registered from ? -1 if none yet */
	int home_node;

	/* what is the default write-through mask for that data ? */
	uint32_t wt_mask;

	/* allows special optimization */
	uint8_t is_readonly;

	/* in some case, the application may explicitly tell StarPU that a
 	 * piece of data is not likely to be used soon again */
	unsigned is_not_important;

	/* Does StarPU have to enforce some implicit data-dependencies ? */
	unsigned sequential_consistency;

	/* This lock should protect any operation to enforce
	 * sequential_consistency */
	starpu_pthread_mutex_t sequential_consistency_mutex;

	/* The last submitted task (or application data request) that declared
	 * it would modify the piece of data ? Any task accessing the data in a
	 * read-only mode should depend on that task implicitely if the
	 * sequential_consistency flag is enabled. */
	enum starpu_data_access_mode last_submitted_mode;
	struct starpu_task *last_sync_task;
	struct _starpu_task_wrapper_dlist last_submitted_accessors;

	/* If FxT is enabled, we keep track of "ghost dependencies": that is to
	 * say the dependencies that are not needed anymore, but that should
	 * appear in the post-mortem DAG. For instance if we have the sequence
	 * f(Aw) g(Aw), and that g is submitted after the termination of f, we
	 * want to have f->g appear in the DAG even if StarPU does not need to
	 * enforce this dependency anymore.*/
	unsigned last_submitted_ghost_sync_id_is_valid;
	unsigned long last_submitted_ghost_sync_id;
	struct _starpu_jobid_list *last_submitted_ghost_accessors_id;

	/* protected by sequential_consistency_mutex */
	struct _starpu_task_wrapper_list *post_sync_tasks;
	unsigned post_sync_tasks_cnt;

	/*
	 *	Reductions
	 */

	/* During reduction we need some specific methods: redux_func performs
	 * the reduction of an interface into another one (eg. "+="), and init_func
	 * initializes the data interface to a default value that is stable by
	 * reduction (eg. 0 for +=). */
	struct starpu_codelet *redux_cl;
	struct starpu_codelet *init_cl;

	/* Are we currently performing a reduction on that handle ? If so the
	 * reduction_refcnt should be non null until there are pending tasks
	 * that are performing the reduction. */
	unsigned reduction_refcnt;

	/* List of requesters that are specific to the pending reduction. This
	 * list is used when the requests in the req_list list are frozen until
	 * the end of the reduction. */
	struct _starpu_data_requester_list reduction_req_list;

	starpu_data_handle_t *reduction_tmp_handles;

	unsigned lazy_unregister;

#ifdef STARPU_OPENMP
	unsigned removed_from_context_hash;
#endif

        /* Used for MPI */
	void *mpi_data;

	_starpu_memory_stats_t memory_stats;

	unsigned int mf_node; //XXX

	/* hook to be called when unregistering the data */
	_starpu_data_handle_unregister_hook unregister_hook;

	struct starpu_arbiter *arbiter;
	/* This is protected by the arbiter mutex */
	struct _starpu_data_requester_list arbitered_req_list;
};

void _starpu_display_msi_stats(void);

/* This does not take a reference on the handle, the caller has to do it,
 * e.g. through _starpu_attempt_to_submit_data_request_from_apps()
 * detached means that the core is allowed to drop the request. The caller
 * should thus *not* take a reference since it can not know whether the request will complete
 * async means that _starpu_fetch_data_on_node will wait for completion of the request
 */
int _starpu_fetch_data_on_node(starpu_data_handle_t handle, struct _starpu_data_replicate *replicate,
			       enum starpu_data_access_mode mode, unsigned detached, unsigned is_prefetch, unsigned async,
			       void (*callback_func)(void *), void *callback_arg);
/* This releases a reference on the handle */
void _starpu_release_data_on_node(struct _starpu_data_state *state, uint32_t default_wt_mask,
				  struct _starpu_data_replicate *replicate);

void _starpu_update_data_state(starpu_data_handle_t handle,
			       struct _starpu_data_replicate *requesting_replicate,
			       enum starpu_data_access_mode mode);

uint32_t _starpu_get_data_refcnt(struct _starpu_data_state *state, unsigned node);

size_t _starpu_data_get_size(starpu_data_handle_t handle);

uint32_t _starpu_data_get_footprint(starpu_data_handle_t handle);

void _starpu_push_task_output(struct _starpu_job *j);

STARPU_ATTRIBUTE_WARN_UNUSED_RESULT
int _starpu_fetch_task_input(struct _starpu_job *j);

unsigned _starpu_is_data_present_or_requested(struct _starpu_data_state *state, unsigned node);

int _starpu_select_src_node(struct _starpu_data_state *state, unsigned destination);

/* is_prefetch is whether the DSM may drop the request (when there is not enough memory for instance
 * async is whether the caller wants a reference on the last request, to be
 * able to wait for it (which will release that reference).
 */
struct _starpu_data_request *_starpu_create_request_to_fetch_data(starpu_data_handle_t handle,
								  struct _starpu_data_replicate *dst_replicate,
								  enum starpu_data_access_mode mode, unsigned is_prefetch,
								  unsigned async,
								  void (*callback_func)(void *), void *callback_arg);

void _starpu_redux_init_data_replicate(starpu_data_handle_t handle, struct _starpu_data_replicate *replicate, int workerid);
void _starpu_data_start_reduction_mode(starpu_data_handle_t handle);
void _starpu_data_end_reduction_mode(starpu_data_handle_t handle);
void _starpu_data_end_reduction_mode_terminate(starpu_data_handle_t handle);

void _starpu_data_set_unregister_hook(starpu_data_handle_t handle, _starpu_data_handle_unregister_hook func);

#endif // __COHERENCY__H__