1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . T A S K _ I N F O --
-- --
-- S p e c --
-- --
-- --
-- Copyright (C) 1992-2000 Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package contains the definitions and routines associated with the
-- implementation of the Task_Info pragma.
-- This is the NetBSD (native) version of this module.
with System.OS_Interface;
with Unchecked_Deallocation;
package System.Task_Info is
pragma Elaborate_Body;
-- To ensure that a body is allowed
-----------------------------------------------------
-- Binding of Tasks to LWPs and LWPs to processors --
-----------------------------------------------------
-- The NetBSD implementation of the GNU Low-Level Interface (GNULLI)
-- implements each Ada task as a NetBSD thread. The NetBSD thread
-- library distributes threads across one or more LWPs (Light Weight
-- Process) that are members of the same process. NetBSD distributes
-- processes and LWPs across the available CPUs on a given machine. The
-- pragma Task_Info provides the mechanism to control the distribution
-- of tasks to LWPs, and LWPs to processors.
-- Each thread has a number of attributes that dictate it's scheduling.
-- These attributes are:
--
-- New_LWP: whether a new LWP is created for this thread.
--
-- Bound_To_LWP: whether the thread is bound to a specific LWP
-- for its entire lifetime.
--
-- CPU: the CPU number associated to the LWP
--
-- The Task_Info pragma:
-- pragma Task_Info (EXPRESSION);
-- allows the specification on a task by task basis of a value of type
-- System.Task_Info.Task_Info_Type to be passed to a task when it is
-- created. The specification of this type, and the effect on the task
-- that is created is target dependent.
-- The Task_Info pragma appears within a task definition (compare the
-- definition and implementation of pragma Priority). If no such pragma
-- appears, then the value Task_Info_Unspecified is passed. If a pragma
-- is present, then it supplies an alternative value. If the argument of
-- the pragma is a discriminant reference, then the value can be set on
-- a task by task basis by supplying the appropriate discriminant value.
-- Note that this means that the type used for Task_Info_Type must be
-- suitable for use as a discriminant (i.e. a scalar or access type).
-----------------------
-- Thread Attributes --
-----------------------
subtype CPU_Number is System.OS_Interface.processorid_t;
CPU_UNCHANGED : constant CPU_Number := System.OS_Interface.PBIND_QUERY;
-- Do not bind the LWP to a specific processor
ANY_CPU : constant CPU_Number := System.OS_Interface.PBIND_NONE;
-- Bind the LWP to any processor
Invalid_CPU_Number : exception;
type Thread_Attributes (New_LWP : Boolean) is record
Bound_To_LWP : Boolean := True;
case New_LWP is
when False =>
null;
when True =>
CPU : CPU_Number := CPU_UNCHANGED;
end case;
end record;
Default_Thread_Attributes : constant Thread_Attributes := (False, True);
function Unbound_Thread_Attributes
return Thread_Attributes;
function Bound_Thread_Attributes
return Thread_Attributes;
function Bound_Thread_Attributes (CPU : CPU_Number)
return Thread_Attributes;
type Task_Info_Type is access all Thread_Attributes;
function New_Unbound_Thread_Attributes
return Task_Info_Type;
function New_Bound_Thread_Attributes
return Task_Info_Type;
function New_Bound_Thread_Attributes (CPU : CPU_Number)
return Task_Info_Type;
type Task_Image_Type is access String;
-- Used to generate a meaningful identifier for tasks that are variables
-- and components of variables.
procedure Free_Task_Image is new
Unchecked_Deallocation (String, Task_Image_Type);
Unspecified_Task_Info : constant Task_Info_Type := null;
end System.Task_Info;
|
