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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- SYSTEM.MULTIPROCESSORS.DISPATCHING_DOMAINS --
-- --
-- B o d y --
-- --
-- Copyright (C) 2011-2022, Free Software Foundation, Inc. --
-- --
-- GNARL 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 3, 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. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
------------------------------------------------------------------------------
-- Body used on targets where the operating system supports setting task
-- affinities.
with System.Tasking.Initialization;
with System.Task_Primitives.Operations; use System.Task_Primitives.Operations;
with Ada.Unchecked_Conversion;
package body System.Multiprocessors.Dispatching_Domains is
package ST renames System.Tasking;
-----------------------
-- Local subprograms --
-----------------------
function Convert_Ids is new
Ada.Unchecked_Conversion (Ada.Task_Identification.Task_Id, ST.Task_Id);
procedure Unchecked_Set_Affinity
(Domain : ST.Dispatching_Domain_Access;
CPU : CPU_Range;
T : ST.Task_Id);
-- Internal procedure to move a task to a target domain and CPU. No checks
-- are performed about the validity of the domain and the CPU because they
-- are done by the callers of this procedure (either Assign_Task or
-- Set_CPU).
procedure Freeze_Dispatching_Domains;
pragma Export
(Ada, Freeze_Dispatching_Domains, "__gnat_freeze_dispatching_domains");
-- Signal the time when no new dispatching domains can be created. It
-- should be called before the environment task calls the main procedure
-- (and after the elaboration code), so the binder-generated file needs to
-- import and call this procedure.
-----------------
-- Assign_Task --
-----------------
procedure Assign_Task
(Domain : in out Dispatching_Domain;
CPU : CPU_Range := Not_A_Specific_CPU;
T : Ada.Task_Identification.Task_Id :=
Ada.Task_Identification.Current_Task)
is
Target : constant ST.Task_Id := Convert_Ids (T);
begin
-- The exception Dispatching_Domain_Error is propagated if T is already
-- assigned to a Dispatching_Domain other than
-- System_Dispatching_Domain, or if CPU is not one of the processors of
-- Domain (and is not Not_A_Specific_CPU).
if Dispatching_Domain (Target.Common.Domain) /= System_Dispatching_Domain
then
raise Dispatching_Domain_Error with
"task already in user-defined dispatching domain";
elsif CPU /= Not_A_Specific_CPU and then CPU not in Domain'Range then
raise Dispatching_Domain_Error with
"processor does not belong to dispatching domain";
end if;
-- Assigning a task to System_Dispatching_Domain that is already
-- assigned to that domain has no effect.
if Domain = System_Dispatching_Domain then
return;
else
-- Set the task affinity once we know it is possible
Unchecked_Set_Affinity
(ST.Dispatching_Domain_Access (Domain), CPU, Target);
end if;
end Assign_Task;
------------
-- Create --
------------
function Create (First : CPU; Last : CPU_Range) return Dispatching_Domain is
begin
return Create ([First .. Last => True]);
end Create;
function Create (Set : CPU_Set) return Dispatching_Domain is
ST_DD : aliased constant ST.Dispatching_Domain :=
ST.Dispatching_Domain (Set);
First : constant CPU := Get_First_CPU (ST_DD'Unrestricted_Access);
Last : constant CPU_Range := Get_Last_CPU (ST_DD'Unrestricted_Access);
subtype Rng is CPU_Range range First .. Last;
use type ST.Dispatching_Domain;
use type ST.Dispatching_Domain_Access;
use type ST.Task_Id;
T : ST.Task_Id;
New_System_Domain : ST.Dispatching_Domain := ST.System_Domain.all;
ST_DD_Slice : constant ST.Dispatching_Domain := ST_DD (Rng);
begin
-- The set of processors for creating a dispatching domain must
-- comply with the following restrictions:
-- - Not exceeding the range of available processors.
-- - CPUs from the System_Dispatching_Domain.
-- - The calling task must be the environment task.
-- - The call to Create must take place before the call to the main
-- subprogram.
-- - Set does not contain a processor with a task assigned to it.
-- - The allocation cannot leave System_Dispatching_Domain empty.
-- Note that a previous version of the language forbade empty domains.
if Rng'Last > Number_Of_CPUs then
raise Dispatching_Domain_Error with
"CPU not supported by the target";
end if;
declare
System_Domain_Slice : constant ST.Dispatching_Domain :=
ST.System_Domain (Rng);
Actual : constant ST.Dispatching_Domain :=
ST_DD_Slice and not System_Domain_Slice;
Expected : constant ST.Dispatching_Domain := [Rng => False];
begin
if Actual /= Expected then
raise Dispatching_Domain_Error with
"CPU not currently in System_Dispatching_Domain";
end if;
end;
if Self /= Environment_Task then
raise Dispatching_Domain_Error with
"only the environment task can create dispatching domains";
end if;
if ST.Dispatching_Domains_Frozen then
raise Dispatching_Domain_Error with
"cannot create dispatching domain after call to main procedure";
end if;
for Proc in Rng loop
if ST_DD (Proc) and then
ST.Dispatching_Domain_Tasks (Proc) /= 0
then
raise Dispatching_Domain_Error with "CPU has tasks assigned";
end if;
end loop;
New_System_Domain (Rng) := New_System_Domain (Rng) and not ST_DD_Slice;
if New_System_Domain = [New_System_Domain'Range => False] then
raise Dispatching_Domain_Error with
"would leave System_Dispatching_Domain empty";
end if;
return Result : constant Dispatching_Domain :=
new ST.Dispatching_Domain'(ST_DD_Slice)
do
-- At this point we need to fix the processors belonging to the
-- system domain, and change the affinity of every task that has
-- been created and assigned to the system domain.
ST.Initialization.Defer_Abort (Self);
Lock_RTS;
ST.System_Domain (Rng) := New_System_Domain (Rng);
pragma Assert (ST.System_Domain.all = New_System_Domain);
-- Iterate the list of tasks belonging to the default system
-- dispatching domain and set the appropriate affinity.
T := ST.All_Tasks_List;
while T /= null loop
if T.Common.Domain = ST.System_Domain then
Set_Task_Affinity (T);
end if;
T := T.Common.All_Tasks_Link;
end loop;
Unlock_RTS;
ST.Initialization.Undefer_Abort (Self);
end return;
end Create;
-----------------------------
-- Delay_Until_And_Set_CPU --
-----------------------------
procedure Delay_Until_And_Set_CPU
(Delay_Until_Time : Ada.Real_Time.Time;
CPU : CPU_Range)
is
begin
-- Not supported atomically by the underlying operating systems.
-- Operating systems use to migrate the task immediately after the call
-- to set the affinity.
delay until Delay_Until_Time;
Set_CPU (CPU);
end Delay_Until_And_Set_CPU;
--------------------------------
-- Freeze_Dispatching_Domains --
--------------------------------
procedure Freeze_Dispatching_Domains is
begin
-- Signal the end of the elaboration code
ST.Dispatching_Domains_Frozen := True;
end Freeze_Dispatching_Domains;
-------------
-- Get_CPU --
-------------
function Get_CPU
(T : Ada.Task_Identification.Task_Id :=
Ada.Task_Identification.Current_Task) return CPU_Range
is
begin
return Convert_Ids (T).Common.Base_CPU;
end Get_CPU;
-----------------
-- Get_CPU_Set --
-----------------
function Get_CPU_Set (Domain : Dispatching_Domain) return CPU_Set is
begin
return CPU_Set (Domain.all);
end Get_CPU_Set;
----------------------------
-- Get_Dispatching_Domain --
----------------------------
function Get_Dispatching_Domain
(T : Ada.Task_Identification.Task_Id :=
Ada.Task_Identification.Current_Task) return Dispatching_Domain
is
begin
return Result : constant Dispatching_Domain :=
Dispatching_Domain (Convert_Ids (T).Common.Domain)
do
pragma Assert (Result /= null);
end return;
end Get_Dispatching_Domain;
-------------------
-- Get_First_CPU --
-------------------
function Get_First_CPU (Domain : Dispatching_Domain) return CPU is
begin
for Proc in Domain'Range loop
if Domain (Proc) then
return Proc;
end if;
end loop;
return CPU'First;
end Get_First_CPU;
------------------
-- Get_Last_CPU --
------------------
function Get_Last_CPU (Domain : Dispatching_Domain) return CPU_Range is
begin
for Proc in reverse Domain'Range loop
if Domain (Proc) then
return Proc;
end if;
end loop;
return CPU_Range'First;
end Get_Last_CPU;
-------------
-- Set_CPU --
-------------
procedure Set_CPU
(CPU : CPU_Range;
T : Ada.Task_Identification.Task_Id :=
Ada.Task_Identification.Current_Task)
is
Target : constant ST.Task_Id := Convert_Ids (T);
begin
-- The exception Dispatching_Domain_Error is propagated if CPU is not
-- one of the processors of the Dispatching_Domain on which T is
-- assigned (and is not Not_A_Specific_CPU).
if CPU /= Not_A_Specific_CPU and then
(CPU not in Target.Common.Domain'Range or else
not Target.Common.Domain (CPU))
then
raise Dispatching_Domain_Error with
"processor does not belong to the task's dispatching domain";
end if;
Unchecked_Set_Affinity (Target.Common.Domain, CPU, Target);
end Set_CPU;
----------------------------
-- Unchecked_Set_Affinity --
----------------------------
procedure Unchecked_Set_Affinity
(Domain : ST.Dispatching_Domain_Access;
CPU : CPU_Range;
T : ST.Task_Id)
is
Source_CPU : constant CPU_Range := T.Common.Base_CPU;
use type ST.Dispatching_Domain_Access;
begin
Write_Lock (T);
-- Move to the new domain
T.Common.Domain := Domain;
-- Attach the CPU to the task
T.Common.Base_CPU := CPU;
-- Change the number of tasks attached to a given task in the system
-- domain if needed.
if not ST.Dispatching_Domains_Frozen
and then (Domain = null or else Domain = ST.System_Domain)
then
-- Reduce the number of tasks attached to the CPU from which this
-- task is being moved, if needed.
if Source_CPU /= Not_A_Specific_CPU then
ST.Dispatching_Domain_Tasks (Source_CPU) :=
ST.Dispatching_Domain_Tasks (Source_CPU) - 1;
end if;
-- Increase the number of tasks attached to the CPU to which this
-- task is being moved, if needed.
if CPU /= Not_A_Specific_CPU then
ST.Dispatching_Domain_Tasks (CPU) :=
ST.Dispatching_Domain_Tasks (CPU) + 1;
end if;
end if;
-- Change the actual affinity calling the operating system level
Set_Task_Affinity (T);
Unlock (T);
end Unchecked_Set_Affinity;
end System.Multiprocessors.Dispatching_Domains;