source: trunk/kernel/kern/dqdt.h @ 582

Last change on this file since 582 was 582, checked in by alain, 3 years ago

New DQDT implementation supporting missing clusters
thanks to the cluster_info[x][y] array.

File size: 7.5 KB
Line 
1/*
2 * kern/dqdt.h - Distributed Quad Decision Tree
3 *
4 * Author : Alain Greiner (2016,2017,2018)
5 *
6 * Copyright (c)  UPMC Sorbonne Universites
7 *
8 * This file is part of ALMOS-MKH
9 *
10 * ALMOS-kernel is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; version 2.0 of the License.
13 *
14 * ALMOS-kernel is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with ALMOS-kernel; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#ifndef _DQDT_H_
25#define _DQDT_H_
26
27#include <kernel_config.h>
28#include <hal_kernel_types.h>
29#include <hal_atomic.h>
30
31/****************************************************************************************
32 * This DQDT infrastructure maintains a topological description of ressources usage
33 * in each cluster: number of threads, and number of physical pages allocated.
34 *
35 * - If X_SIZE or Y_SIZE are equal to 1, it makes the assumption that the cluster
36 *   topology is a one dimensionnal vector, an build the smallest one-dimensionnal
37 *   quad-tree covering this one-dimensionnal vector. If the number of clusters
38 *   is not a power of 4, the tree is truncated as required.
39 *
40 *   TODO : the mapping for the one dimensionnal topology is not implemented yet [AG].
41 *
42 * - If both Y_SIZE and Y_SIZE are larger than 1, it makes the assumption that
43 *   the clusters topology is a 2D mesh. The [X,Y] coordinates of a cluster are
44 *   obtained from the CXY identifier using the Rrelevant macros.
45 *      X = CXY >> Y_WIDTH   /  Y = CXY & ((1<<Y_WIDTH)-1)
46 * - If the mesh X_SIZE and Y_SIZE dimensions are not equal, or are not power of 2,
47 *   or the mesh contains "holes" reported in the cluster_info[x][y] array,
48 *   we build the smallest two dimensionnal quad-tree covering all clusters,
49 *   and this tree is truncated as required.
50 * - The mesh size is supposed to contain at most 32 * 32 clusters.
51 *   Therefore, it can exist at most 6 DQDT nodes in a given cluster:
52 *   . Level 0 nodes exist on all clusters and have no children.
53 *   . Level 1 nodes exist when both X and Y coordinates are multiple of 2
54 *   . Level 2 nodes exist when both X and Y coordinates are multiple of 4
55 *   . Level 3 nodes exist when both X and Y coordinates are multiple of 8
56 *   . Level 4 nodes exist when both X and Y coordinates are multiple of 16
57 *   . Level 5 nodes exist when both X and Y coordinates are multiple of 32
58 * - For nodes other than level 0, the placement is defined as follow:
59 *   . The root node is placed in the cluster containing the core executing
60 *     the dqdt_init() function.
61 *   . An intermediate node (representing a given sub-tree) is placed in one
62 *     cluster covered by the subtree, pseudo-randomly selected.
63 ***************************************************************************************/
64
65/****************************************************************************************
66 * This structure describes a node of the DQDT.
67 * The max number of children is 4, but it can be smaller for some nodes.
68 * Level 0 nodes are the clusters, and have no children.
69 * The root node has no parent.
70 ***************************************************************************************/
71
72typedef struct dqdt_node_s
73{
74        uint32_t            level;               // node level
75        uint32_t            arity;               // actual children number in this node
76    uint32_t            threads;             // current number of threads in subtree
77    uint32_t            pages;               // current number of pages in subtree
78        xptr_t              parent;              // extended pointer on parent node
79        xptr_t              children[2][2];      // extended pointers on children nodes
80}
81dqdt_node_t;
82
83
84/****************************************************************************************
85 * This function recursively initializes the DQDT structure from informations
86 * stored in cluster manager (x_size, y_size and cluster_info[x][y].
87 * It is executed in all clusters by the local CP0, to compute level_max and register
88 * the DQDT root node in each cluster manager, but only CPO in cluster 0 build actually
89 * the quad-tree covering all active clusters.
90 * This initialisation can use remote_accesses, because the DQDT nodes are
91 * allocated as global variables in the cluster_manager, and the local addresses
92 * are identical in all clusters.
93 ***************************************************************************************/
94void dqdt_init( void );
95
96/****************************************************************************************
97 * This local function updates the total number of threads in level 0 DQDT node,
98 * and propagates the variation to the DQDT upper levels.
99 * It should be called on each thread creation or destruction.
100 ****************************************************************************************
101 * @ increment : increment (can be positive or negative)
102 ***************************************************************************************/
103void dqdt_update_threads( int32_t  increment );
104
105/****************************************************************************************
106 * This local function updates the total number of pages in level 0 DQDT node,
107 * and propagates the variation to the DQDT upper levels.
108 * It should be called on each physical memory page allocation or release.
109 ****************************************************************************************
110 * @ increment : increment (can be positive or negative)
111 ***************************************************************************************/
112void dqdt_update_pages( int32_t increment );
113
114/****************************************************************************************
115 * This function can be called in any cluster. It traverses the DQDT tree
116 * from the root to the bottom, to analyse the computing load and select the cluster
117 * with the lowest number ot threads to place a new process.
118 ****************************************************************************************
119 * @ returns the cluster identifier with the lowest computing load.
120 ***************************************************************************************/
121cxy_t dqdt_get_cluster_for_process( void );
122
123/****************************************************************************************
124 * This function can be called in any cluster. It traverses the DQDT tree
125 * from the root to the bottom, to analyse the memory load and select the cluster
126 * with the lowest memory load for dynamic memory allocation with no locality constraint.
127 ****************************************************************************************
128 * @ returns the cluster identifier with the lowest memory load.
129 ***************************************************************************************/
130cxy_t dqdt_get_cluster_for_memory( void );
131
132/****************************************************************************************
133 * This function displays on kernel TXT0 the DQDT state for all nodes in the quad-tree.
134 * It traverses the quadtree from root to bottom, and can be called by a thread
135 * running in any cluster
136 ***************************************************************************************/
137void dqdt_display( void );
138
139
140#endif  /* _DQDT_H_ */
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