source: soft/giet_vm/giet_libs/barrier.h @ 475

Last change on this file since 475 was 468, checked in by alain, 10 years ago

Cosmetic: Improving debug.

  • Property svn:executable set to *
File size: 4.7 KB
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1//////////////////////////////////////////////////////////////////////////////////
2// File     : barrier.h         
3// Date     : 01/04/2012
4// Author   : alain greiner
5// Copyright (c) UPMC-LIP6
6///////////////////////////////////////////////////////////////////////////////////
7// The barrier.c and barrier.h files are part of the GIET-VM nano-kernel.
8// This user-level library provides a synchronisation service between several
9// tasks sharing the same address space in a parallel multi-tasks application.
10//
11// There is actually two types of barriers:
12// 1) The "giet_barrier_t" is a simple sense-reversing barrier.
13//    It can be safely used several times (in a loop for example),
14//    but it does not scale, and should not be used when the number
15//    of tasks is larger than few tens.
16//
17// 2) The giet_sbt_barrier_t" can be used in multi-clusters architectures,
18//    and is implemented as a physically distributed Sliced-Binary-Tree (SBT).
19//    WARNING: The following placement constraints must be respected:
20//    - The number of tasks must be a power of 2.
21//    - There is one task per processor in a given cluster.
22//    - The involved clusters form a mesh[N][N] or a mesh[N][N/2]
23//    - The lower left involved cluster is cluster(0,0) 
24//
25// Neither the barrier_init(), nor the barrier_wait() function require a syscall.
26// For both types of barriers, the barrier initialisation should be done by
27// one single task.
28///////////////////////////////////////////////////////////////////////////////////
29
30#ifndef _BARRIER_H_
31#define _BARRIER_H_
32
33#include "hard_config.h"
34
35///////////////////////////////////////////////////////////////////////////////////
36///////////////////////////////////////////////////////////////////////////////////
37//  simple barrier structure and access functions
38///////////////////////////////////////////////////////////////////////////////////
39///////////////////////////////////////////////////////////////////////////////////
40
41typedef struct giet_barrier_s
42{
43    char         name[32];   // barrier name
44    unsigned int sense;      // barrier state (toggle)
45    unsigned int ntasks;     // total number of expected tasks
46    unsigned int count;      // number of not arrived tasks
47} giet_barrier_t;
48
49///////////////////////////////////////////////////
50extern void barrier_init( giet_barrier_t* barrier,
51                          unsigned int    ntasks );   
52
53////////////////////////////////////////////////////
54extern void barrier_wait( giet_barrier_t* barrier );
55
56///////////////////////////////////////////////////////////////////////////////////
57//////////////////////////////////////////////////////////////////////////////////
58// SBT barrier structures and access functions
59//////////////////////////////////////////////////////////////////////////////////
60//////////////////////////////////////////////////////////////////////////////////
61
62typedef struct sbt_node_s
63{
64    unsigned int       arity;           // number of children (must be 2 or 4)
65    unsigned int       count;           // number of not arrived children
66    unsigned int       sense;           // barrier state (toggle)
67    unsigned int       level;           // hierarchical level (0 is bottom)
68    struct sbt_node_s* parent;          // pointer on parent node (NULL for root)
69    struct sbt_node_s* child0;          // pointer on children node
70    struct sbt_node_s* child1;          // pointer on children node
71    unsigned int       padding;         // for 32 bytes alignment
72} sbt_node_t;
73
74typedef struct giet_sbt_barrier_s
75{
76    char            name[32];                 // barrier name
77    unsigned int    ntasks;                   // total number of expected tasks
78    sbt_node_t*     node[X_SIZE][Y_SIZE][9];  // array of pointers on SBT nodes
79} giet_sbt_barrier_t;
80
81///////////////////////////////////////////////////////////
82extern void sbt_barrier_init( giet_sbt_barrier_t*  barrier,
83                              unsigned int         ntasks );   
84
85/////////////////////////////////////////////////////////////
86extern void sbt_barrier_wait( giet_sbt_barrier_t*  barrier );
87
88/////////////////////////////////////////////
89void sbt_build( giet_sbt_barrier_t*  barrier,
90                unsigned int         x,
91                unsigned int         y,
92                unsigned int         level, 
93                sbt_node_t*          parent );
94
95///////////////////////////////////////
96void sbt_decrement( sbt_node_t* node );
97
98///////////////////////////////////
99void sbt_release( sbt_node_t* node,
100                  unsigned int expected );
101
102
103
104#endif
105
106// Local Variables:
107// tab-width: 4
108// c-basic-offset: 4
109// c-file-offsets:((innamespace . 0)(inline-open . 0))
110// indent-tabs-mode: nil
111// End:
112// vim: filetype=c:expandtab:shiftwidth=4:tabstop=4:softtabstop=4
113
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