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4078b7760e
The old barrier implementation was very slow when running on a multi-socket machine (pcmemtest issue 16). The new implementation provides two options: - when blocked, spin on a thread-local flag - when blocked, execute a HLT instruction and wait for a NMI The first option might be faster, but we need to measure it to find out. A new boot command line option is provided to select between the two, with a third setting that uses a mixture of the two.
83 lines
1.6 KiB
C
83 lines
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef _SMP_H_
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#define _SMP_H_
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/**
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* \file
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*
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* Provides support for multi-threaded operation.
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*
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*//*
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* Copyright (C) 2020-2022 Martin Whitaker.
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*/
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#include <stdbool.h>
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#include <stdint.h>
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#include "boot.h"
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#include "barrier.h"
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#include "spinlock.h"
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/**
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* The maximum number of CPU cores that can be used.
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*/
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#define MAX_CPUS (1 + MAX_APS)
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/**
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* The current state of a CPU core.
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*/
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typedef enum __attribute__ ((packed)) {
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CPU_STATE_DISABLED = 0,
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CPU_STATE_ENABLED = 1,
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CPU_STATE_RUNNING = 2
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} cpu_state_t;
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/**
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* The number of available CPU cores. Initially this is 1, but may increase
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* after calling smp_init().
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*/
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extern int num_available_cpus;
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/**
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* The search step that located the ACPI RSDP (for debug).
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*/
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extern const char *rsdp_source;
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/**
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* The address of the ACPI RSDP (for debug).
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*/
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extern uintptr_t rsdp_addr;
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/**
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* Initialises the SMP state and detects the number of available CPU cores.
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*/
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void smp_init(bool smp_enable);
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/**
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* Starts the APs listed as enabled in cpu_state. Returns 0 on success
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* or the index number of the lowest-numbered AP that failed to start.
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*/
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int smp_start(cpu_state_t cpu_state[MAX_CPUS]);
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/**
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* Sends a non-maskable interrupt to the CPU core whose ordinal number
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* is cpu_num.
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*/
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void smp_send_nmi(int cpu_num);
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/**
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* Returns the ordinal number of the calling CPU core.
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*/
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int smp_my_cpu_num(void);
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/**
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* Allocates and initialises a barrier object in pinned memory.
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*/
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barrier_t *smp_alloc_barrier(int num_threads);
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/**
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* Allocates and initialises a spinlock object in pinned memory.
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*/
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spinlock_t *smp_alloc_mutex();
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#endif /* _SMP_H_ */
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