zephyr/kernel/ipi.c

109 lines
2.7 KiB
C

/**
* Copyright (c) 2024 Intel Corporation
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/kernel.h>
#include <kswap.h>
#include <ksched.h>
#include <ipi.h>
#ifdef CONFIG_TRACE_SCHED_IPI
extern void z_trace_sched_ipi(void);
#endif
void flag_ipi(uint32_t ipi_mask)
{
#if defined(CONFIG_SCHED_IPI_SUPPORTED)
if (arch_num_cpus() > 1) {
atomic_or(&_kernel.pending_ipi, (atomic_val_t)ipi_mask);
}
#endif /* CONFIG_SCHED_IPI_SUPPORTED */
}
/* Create a bitmask of CPUs that need an IPI. Note: sched_spinlock is held. */
atomic_val_t ipi_mask_create(struct k_thread *thread)
{
if (!IS_ENABLED(CONFIG_IPI_OPTIMIZE)) {
return (CONFIG_MP_MAX_NUM_CPUS > 1) ? IPI_ALL_CPUS_MASK : 0;
}
uint32_t ipi_mask = 0;
uint32_t num_cpus = (uint32_t)arch_num_cpus();
uint32_t id = _current_cpu->id;
struct k_thread *cpu_thread;
bool executable_on_cpu = true;
for (uint32_t i = 0; i < num_cpus; i++) {
if (id == i) {
continue;
}
/*
* An IPI absolutely does not need to be sent if ...
* 1. the CPU is not active, or
* 2. <thread> can not execute on the target CPU
* ... and might not need to be sent if ...
* 3. the target CPU's active thread is not preemptible, or
* 4. the target CPU's active thread has a higher priority
* (Items 3 & 4 may be overridden by a metaIRQ thread)
*/
#if defined(CONFIG_SCHED_CPU_MASK)
executable_on_cpu = ((thread->base.cpu_mask & BIT(i)) != 0);
#endif
cpu_thread = _kernel.cpus[i].current;
if ((cpu_thread != NULL) &&
(((z_sched_prio_cmp(cpu_thread, thread) < 0) &&
(thread_is_preemptible(cpu_thread))) ||
thread_is_metairq(thread)) && executable_on_cpu) {
ipi_mask |= BIT(i);
}
}
return (atomic_val_t)ipi_mask;
}
void signal_pending_ipi(void)
{
/* Synchronization note: you might think we need to lock these
* two steps, but an IPI is idempotent. It's OK if we do it
* twice. All we require is that if a CPU sees the flag true,
* it is guaranteed to send the IPI, and if a core sets
* pending_ipi, the IPI will be sent the next time through
* this code.
*/
#if defined(CONFIG_SCHED_IPI_SUPPORTED)
if (arch_num_cpus() > 1) {
uint32_t cpu_bitmap;
cpu_bitmap = (uint32_t)atomic_clear(&_kernel.pending_ipi);
if (cpu_bitmap != 0) {
#ifdef CONFIG_ARCH_HAS_DIRECTED_IPIS
arch_sched_directed_ipi(cpu_bitmap);
#else
arch_sched_broadcast_ipi();
#endif
}
}
#endif /* CONFIG_SCHED_IPI_SUPPORTED */
}
void z_sched_ipi(void)
{
/* NOTE: When adding code to this, make sure this is called
* at appropriate location when !CONFIG_SCHED_IPI_SUPPORTED.
*/
#ifdef CONFIG_TRACE_SCHED_IPI
z_trace_sched_ipi();
#endif /* CONFIG_TRACE_SCHED_IPI */
#ifdef CONFIG_TIMESLICING
if (thread_is_sliceable(_current)) {
z_time_slice();
}
#endif /* CONFIG_TIMESLICING */
}