402 lines
14 KiB
Ada
402 lines
14 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- SYSTEM.MULTIPROCESSORS.DISPATCHING_DOMAINS --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2011-2020, Free Software Foundation, Inc. --
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-- --
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-- GNARL is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNARL was developed by the GNARL team at Florida State University. --
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-- Extensive contributions were provided by Ada Core Technologies, Inc. --
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-- --
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------------------------------------------------------------------------------
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-- Body used on targets where the operating system supports setting task
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-- affinities.
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with System.Tasking.Initialization;
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with System.Task_Primitives.Operations; use System.Task_Primitives.Operations;
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with Ada.Unchecked_Conversion;
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package body System.Multiprocessors.Dispatching_Domains is
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package ST renames System.Tasking;
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-----------------------
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-- Local subprograms --
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-----------------------
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function Convert_Ids is new
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Ada.Unchecked_Conversion (Ada.Task_Identification.Task_Id, ST.Task_Id);
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procedure Unchecked_Set_Affinity
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(Domain : ST.Dispatching_Domain_Access;
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CPU : CPU_Range;
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T : ST.Task_Id);
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-- Internal procedure to move a task to a target domain and CPU. No checks
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-- are performed about the validity of the domain and the CPU because they
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-- are done by the callers of this procedure (either Assign_Task or
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-- Set_CPU).
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procedure Freeze_Dispatching_Domains;
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pragma Export
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(Ada, Freeze_Dispatching_Domains, "__gnat_freeze_dispatching_domains");
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-- Signal the time when no new dispatching domains can be created. It
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-- should be called before the environment task calls the main procedure
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-- (and after the elaboration code), so the binder-generated file needs to
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-- import and call this procedure.
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-----------------
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-- Assign_Task --
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-----------------
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procedure Assign_Task
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(Domain : in out Dispatching_Domain;
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CPU : CPU_Range := Not_A_Specific_CPU;
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T : Ada.Task_Identification.Task_Id :=
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Ada.Task_Identification.Current_Task)
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is
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Target : constant ST.Task_Id := Convert_Ids (T);
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begin
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-- The exception Dispatching_Domain_Error is propagated if T is already
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-- assigned to a Dispatching_Domain other than
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-- System_Dispatching_Domain, or if CPU is not one of the processors of
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-- Domain (and is not Not_A_Specific_CPU).
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if Dispatching_Domain (Target.Common.Domain) /= System_Dispatching_Domain
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then
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raise Dispatching_Domain_Error with
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"task already in user-defined dispatching domain";
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elsif CPU /= Not_A_Specific_CPU and then CPU not in Domain'Range then
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raise Dispatching_Domain_Error with
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"processor does not belong to dispatching domain";
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end if;
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-- Assigning a task to System_Dispatching_Domain that is already
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-- assigned to that domain has no effect.
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if Domain = System_Dispatching_Domain then
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return;
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else
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-- Set the task affinity once we know it is possible
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Unchecked_Set_Affinity
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(ST.Dispatching_Domain_Access (Domain), CPU, Target);
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end if;
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end Assign_Task;
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------------
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-- Create --
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------------
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function Create (First : CPU; Last : CPU_Range) return Dispatching_Domain is
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begin
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return Create ((First .. Last => True));
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end Create;
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function Create (Set : CPU_Set) return Dispatching_Domain is
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ST_DD : aliased constant ST.Dispatching_Domain :=
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ST.Dispatching_Domain (Set);
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First : constant CPU := Get_First_CPU (ST_DD'Unrestricted_Access);
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Last : constant CPU_Range := Get_Last_CPU (ST_DD'Unrestricted_Access);
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subtype Rng is CPU_Range range First .. Last;
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use type ST.Dispatching_Domain;
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use type ST.Dispatching_Domain_Access;
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use type ST.Task_Id;
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T : ST.Task_Id;
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New_System_Domain : ST.Dispatching_Domain := ST.System_Domain.all;
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ST_DD_Slice : constant ST.Dispatching_Domain := ST_DD (Rng);
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begin
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-- The set of processors for creating a dispatching domain must
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-- comply with the following restrictions:
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-- - Not exceeding the range of available processors.
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-- - CPUs from the System_Dispatching_Domain.
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-- - The calling task must be the environment task.
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-- - The call to Create must take place before the call to the main
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-- subprogram.
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-- - Set does not contain a processor with a task assigned to it.
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-- - The allocation cannot leave System_Dispatching_Domain empty.
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-- Note that a previous version of the language forbade empty domains.
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if Rng'Last > Number_Of_CPUs then
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raise Dispatching_Domain_Error with
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"CPU not supported by the target";
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end if;
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declare
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System_Domain_Slice : constant ST.Dispatching_Domain :=
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ST.System_Domain (Rng);
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Actual : constant ST.Dispatching_Domain :=
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ST_DD_Slice and not System_Domain_Slice;
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Expected : constant ST.Dispatching_Domain := (Rng => False);
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begin
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if Actual /= Expected then
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raise Dispatching_Domain_Error with
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"CPU not currently in System_Dispatching_Domain";
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end if;
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end;
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if Self /= Environment_Task then
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raise Dispatching_Domain_Error with
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"only the environment task can create dispatching domains";
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end if;
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if ST.Dispatching_Domains_Frozen then
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raise Dispatching_Domain_Error with
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"cannot create dispatching domain after call to main procedure";
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end if;
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for Proc in Rng loop
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if ST_DD (Proc) and then
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ST.Dispatching_Domain_Tasks (Proc) /= 0
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then
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raise Dispatching_Domain_Error with "CPU has tasks assigned";
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end if;
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end loop;
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New_System_Domain (Rng) := New_System_Domain (Rng) and not ST_DD_Slice;
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if New_System_Domain = (New_System_Domain'Range => False) then
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raise Dispatching_Domain_Error with
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"would leave System_Dispatching_Domain empty";
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end if;
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return Result : constant Dispatching_Domain :=
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new ST.Dispatching_Domain'(ST_DD_Slice)
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do
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-- At this point we need to fix the processors belonging to the
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-- system domain, and change the affinity of every task that has
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-- been created and assigned to the system domain.
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ST.Initialization.Defer_Abort (Self);
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Lock_RTS;
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ST.System_Domain (Rng) := New_System_Domain (Rng);
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pragma Assert (ST.System_Domain.all = New_System_Domain);
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-- Iterate the list of tasks belonging to the default system
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-- dispatching domain and set the appropriate affinity.
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T := ST.All_Tasks_List;
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while T /= null loop
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if T.Common.Domain = ST.System_Domain then
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Set_Task_Affinity (T);
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end if;
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T := T.Common.All_Tasks_Link;
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end loop;
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Unlock_RTS;
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ST.Initialization.Undefer_Abort (Self);
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end return;
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end Create;
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-----------------------------
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-- Delay_Until_And_Set_CPU --
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-----------------------------
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procedure Delay_Until_And_Set_CPU
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(Delay_Until_Time : Ada.Real_Time.Time;
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CPU : CPU_Range)
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is
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begin
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-- Not supported atomically by the underlying operating systems.
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-- Operating systems use to migrate the task immediately after the call
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-- to set the affinity.
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delay until Delay_Until_Time;
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Set_CPU (CPU);
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end Delay_Until_And_Set_CPU;
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--------------------------------
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-- Freeze_Dispatching_Domains --
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--------------------------------
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procedure Freeze_Dispatching_Domains is
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begin
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-- Signal the end of the elaboration code
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ST.Dispatching_Domains_Frozen := True;
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end Freeze_Dispatching_Domains;
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-------------
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-- Get_CPU --
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-------------
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function Get_CPU
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(T : Ada.Task_Identification.Task_Id :=
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Ada.Task_Identification.Current_Task) return CPU_Range
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is
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begin
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return Convert_Ids (T).Common.Base_CPU;
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end Get_CPU;
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-----------------
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-- Get_CPU_Set --
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-----------------
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function Get_CPU_Set (Domain : Dispatching_Domain) return CPU_Set is
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begin
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return CPU_Set (Domain.all);
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end Get_CPU_Set;
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----------------------------
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-- Get_Dispatching_Domain --
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----------------------------
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function Get_Dispatching_Domain
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(T : Ada.Task_Identification.Task_Id :=
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Ada.Task_Identification.Current_Task) return Dispatching_Domain
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is
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begin
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return Result : constant Dispatching_Domain :=
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Dispatching_Domain (Convert_Ids (T).Common.Domain)
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do
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pragma Assert (Result /= null);
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end return;
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end Get_Dispatching_Domain;
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-------------------
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-- Get_First_CPU --
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-------------------
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function Get_First_CPU (Domain : Dispatching_Domain) return CPU is
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begin
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for Proc in Domain'Range loop
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if Domain (Proc) then
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return Proc;
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end if;
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end loop;
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return CPU'First;
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end Get_First_CPU;
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------------------
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-- Get_Last_CPU --
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------------------
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function Get_Last_CPU (Domain : Dispatching_Domain) return CPU_Range is
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begin
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for Proc in reverse Domain'Range loop
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if Domain (Proc) then
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return Proc;
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end if;
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end loop;
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return CPU_Range'First;
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end Get_Last_CPU;
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-------------
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-- Set_CPU --
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-------------
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procedure Set_CPU
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(CPU : CPU_Range;
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T : Ada.Task_Identification.Task_Id :=
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Ada.Task_Identification.Current_Task)
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is
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Target : constant ST.Task_Id := Convert_Ids (T);
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begin
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-- The exception Dispatching_Domain_Error is propagated if CPU is not
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-- one of the processors of the Dispatching_Domain on which T is
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-- assigned (and is not Not_A_Specific_CPU).
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if CPU /= Not_A_Specific_CPU and then
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(CPU not in Target.Common.Domain'Range or else
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not Target.Common.Domain (CPU))
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then
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raise Dispatching_Domain_Error with
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"processor does not belong to the task's dispatching domain";
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end if;
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Unchecked_Set_Affinity (Target.Common.Domain, CPU, Target);
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end Set_CPU;
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----------------------------
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-- Unchecked_Set_Affinity --
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----------------------------
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procedure Unchecked_Set_Affinity
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(Domain : ST.Dispatching_Domain_Access;
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CPU : CPU_Range;
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T : ST.Task_Id)
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is
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Source_CPU : constant CPU_Range := T.Common.Base_CPU;
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use type ST.Dispatching_Domain_Access;
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begin
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Write_Lock (T);
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-- Move to the new domain
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T.Common.Domain := Domain;
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-- Attach the CPU to the task
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T.Common.Base_CPU := CPU;
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-- Change the number of tasks attached to a given task in the system
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-- domain if needed.
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if not ST.Dispatching_Domains_Frozen
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and then (Domain = null or else Domain = ST.System_Domain)
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then
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-- Reduce the number of tasks attached to the CPU from which this
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-- task is being moved, if needed.
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if Source_CPU /= Not_A_Specific_CPU then
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ST.Dispatching_Domain_Tasks (Source_CPU) :=
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ST.Dispatching_Domain_Tasks (Source_CPU) - 1;
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end if;
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-- Increase the number of tasks attached to the CPU to which this
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-- task is being moved, if needed.
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if CPU /= Not_A_Specific_CPU then
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ST.Dispatching_Domain_Tasks (CPU) :=
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ST.Dispatching_Domain_Tasks (CPU) + 1;
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end if;
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end if;
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-- Change the actual affinity calling the operating system level
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Set_Task_Affinity (T);
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Unlock (T);
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end Unchecked_Set_Affinity;
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end System.Multiprocessors.Dispatching_Domains;
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