This module is in charge of synchronizing time between MPI processes. More...

Data Structures
struct	sync_tree_conf
	This structure describes a tree node for time synchronization. More...

Macros
#define	MAX_LOOP_TRY 20
	the maximum number computations tries More...

#define	SYNC_TAG 1234
	The tag for time sync communications. More...

#define	MAX_AVG 10
	the number of offset computations to perform to get an average offset More...

Functions
void	sync_mpi ()
	Entry point to be used to perform time sync of every MPI Processes. More...

void	compute_sync_tree (struct sync_tree_conf conf, void(action)(struct sync_tree_conf next_conf, void arg), void(per_child_act)(struct sync_tree_conf conf, void arg), void(post_action)(struct sync_tree_conf next_conf, void arg), void *arg)
	This function does the actual work prepared by bootstrap_sync_tree(). More...

void	bootstrap_sync_tree (void(action)(struct sync_tree_conf next_conf, void arg), void(per_child_act)(struct sync_tree_conf conf, void arg), void(post_action)(struct sync_tree_conf next_conf, void arg), void arg)
	This is a bootstrapping function for calling compute_sync_tree();. More...

void	perchild_host (struct sync_tree_conf c, void arg)
	What to be done on each node's child. More...

void	post_client (struct sync_tree_conf c, void arg)
	What to be done on the client side. More...

void	action_set_off (struct sync_tree_conf c, void poffset)
	Copies offset of c to current process timer offset (poffset) More...

void	action_val (struct sync_tree_conf c, void arg)
	For debugging only. More...

void	sync_server (int dest_rank)
	Server function for synchronizing time. More...

void	sync_client (int parent, void *poffset)
	The client function for synchronizing time (computes offset between server and client) More...

static uint64_t	abs_diff (uint64_t a, uint64_t b)
	Computes an absolute difference. More...

static uint32_t	nearest_pow (uint32_t num)
	Computes the nearest. More...

Detailed Description

This module is in charge of synchronizing time between MPI processes.

If MPI Processes are distributed onto several physical nodes, the time (see Timer ) is not consistent from a process to another.

These functions give the possibility to adjust (Process_Sync_Offset) the timers of every processes in order to have synchronized time.

Macro Definition Documentation

#define MAX_AVG 10

the number of offset computations to perform to get an average offset

Definition at line 53 of file Sync_Time_MPI.h.

#define MAX_LOOP_TRY 20

the maximum number computations tries

Definition at line 43 of file Sync_Time_MPI.h.

#define SYNC_TAG 1234

The tag for time sync communications.

Definition at line 48 of file Sync_Time_MPI.h.

Function Documentation

static uint64_t abs_diff	(	uint64_t	a,
		uint64_t	b
	)

inlinestatic

Computes an absolute difference.

Parameters

a	first element
b	second element

Returns: the positive difference between a and b

Definition at line 192 of file Sync_Time_MPI.h.

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void action_set_off	(	struct sync_tree_conf *	c,
		void *	poffset
	)

Copies offset of c to current process timer offset (poffset)

Parameters

c	a node configuration
poffset	the current process timer offset

Definition at line 258 of file Sync_Time_MPI.c.

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void action_val	(	struct sync_tree_conf *	c,
		void *	arg
	)

For debugging only.

Parameters

c	a node configuration
arg	an argument

Prints who synced with who

Definition at line 272 of file Sync_Time_MPI.c.

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void bootstrap_sync_tree	(	void()(struct sync_tree_conf next_conf, void *arg)	action,
		void()(struct sync_tree_conf conf, void *arg)	per_child_act,
		void()(struct sync_tree_conf next_conf, void *arg)	post_action,
		void *	arg
	)

This is a bootstrapping function for calling compute_sync_tree();.

Parameters

action	a function to be called on each node
per_child_act	a function to be called on each child of the node
post_action	a function to be called at the end
arg	an argument to give to the three above functions

For rank 0, it performs initialization of a sync_tree_conf struct, then call compute_sync_tree()
For other ranks, recieves a sync_tree_conf struct from MPI, and then call compute_sync_tree()

The communucation is performed in a tree manner and rank 0 is the tree root.

Definition at line 93 of file Sync_Time_MPI.c.

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void compute_sync_tree	(	struct sync_tree_conf *	conf,
		void()(struct sync_tree_conf next_conf, void *arg)	action,
		void()(struct sync_tree_conf conf, void *arg)	per_child_act,
		void()(struct sync_tree_conf next_conf, void *arg)	post_action,
		void *	arg
	)

This function does the actual work prepared by bootstrap_sync_tree().

Parameters

conf	the sync_tree_conf corresponding to current node
action	a function to be called on each node
per_child_act	a function to be called on each child of the node
post_action	a function to be called at the end
arg	an argument to give to the three above functions

The work is :

run action with conf and arg
compute a sync_tree_conf struct for each child and send it. (retrieved in bootstrap_sync_tree())
for each child, run per_child_act with newly computed sync_tree_conf and arg
run post_action with conf and arg