508c5889d7
reason: 1 To improve efficiency, we mimic Linux's behavior where preemption disabling is only applicable to the current CPU and does not affect other CPUs. 2 In the future, we will implement "spinlock+sched_lock", and use it extensively. Under such circumstances, if preemption is still globally disabled, it will seriously impact the scheduling efficiency. 3 We have removed g_cpu_lockset and used irqcount in order to eliminate the dependency of schedlock on critical sections in the future, simplify the logic, and further enhance the performance of sched_lock. 4 We set lockcount to 1 in order to lock scheduling on all CPUs during startup, without the need to provide additional functions to disable scheduling on other CPUs. 5 Cpu1~n must wait for cpu0 to enter the idle state before enabling scheduling because it prevents CPUs1~n from competing with cpu0 for the memory manager mutex, which could cause the cpu0 idle task to enter a wait state and trigger an assert. size nuttx before: text data bss dec hex filename 265396 51057 63646 380099 5ccc3 nuttx after: text data bss dec hex filename 265184 51057 63642 379883 5cbeb nuttx size -216 Configuring NuttX and compile: $ ./tools/configure.sh -l qemu-armv8a:nsh_smp $ make Running with qemu $ qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic \ -machine virt,virtualization=on,gic-version=3 \ -net none -chardev stdio,id=con,mux=on -serial chardev:con \ -mon chardev=con,mode=readline -kernel ./nuttx Signed-off-by: hujun5 <hujun5@xiaomi.com>
145 lines
4.0 KiB
C
145 lines
4.0 KiB
C
/****************************************************************************
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* sched/init/nx_smpstart.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdio.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/arch.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/sched.h>
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#include <nuttx/sched_note.h>
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#include <nuttx/init.h>
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#include "group/group.h"
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#include "sched/sched.h"
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#include "init/init.h"
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#ifdef CONFIG_SMP
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nx_idle_trampoline
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*
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* Description:
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* This is the common start-up logic for the IDLE task for CPUs 1 through
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* (CONFIG_SMP_NCPUS-1). Having a start-up function such as this for the
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* IDLE is not really an architectural necessity. It is used only for
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* symmetry with how other threads are started (see nxtask_start() and
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* pthread_start()).
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*
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* Input Parameters:
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* None.
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*
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* Returned Value:
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* This function does not return.
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*
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****************************************************************************/
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void nx_idle_trampoline(void)
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{
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#ifdef CONFIG_SCHED_INSTRUMENTATION_SWITCH
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FAR struct tcb_s *tcb = this_task();
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/* Announce that the IDLE task has started */
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sched_note_start(tcb);
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#endif
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/* wait until cpu0 in idle() */
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while (!OSINIT_IDLELOOP());
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sched_unlock();
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/* Enter the IDLE loop */
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sinfo("CPU%d: Beginning Idle Loop\n", this_cpu());
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for (; ; )
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{
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/* Perform any processor-specific idle state operations */
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up_idle();
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}
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}
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/****************************************************************************
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* Name: nx_smp_start
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*
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* Description:
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* In an SMP configuration, only one CPU is initially active (CPU 0).
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* System initialization occurs on that single thread. At the completion
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* of the initialization of the OS, just before beginning normal
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* multitasking, the additional CPUs would be started by calling this
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* function.
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* Zero on success; a negated errno value on failure.
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*
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* Assumption:
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* Runs before the full initialization sequence has completed. Runs after
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* all OS facilities are set up, but before multi-tasking has been started.
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*
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****************************************************************************/
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int nx_smp_start(void)
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{
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int ret;
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int cpu;
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/* Flush dcache before start other CPUs. */
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up_flush_dcache_all();
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/* Start all of the other CPUs. CPU0 is already running. */
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for (cpu = 1; cpu < CONFIG_SMP_NCPUS; cpu++)
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{
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/* Start the CPU */
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ret = up_cpu_start(cpu);
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if (ret < 0)
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{
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serr("ERROR: Failed to start CPU%d: %d\n", cpu, ret);
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return ret;
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}
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}
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return OK;
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}
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#endif /* CONFIG_SMP */
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