rt-thread/src/utest/perf/context_switch_tc.c

/*
 * Copyright (c) 2006-2025, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author         Notes
 * 2025-07-03     rcitach        test case for context_switch
 * 2025-11-30     westcity-YOLO  Add standardized utest documentation block
 */

/*
 * Test Case Name: Kernel Core Context Switch Performance Test
 *
 * Test Objectives:
 * - Measures thread context switch overhead using semaphore synchronization
 * - Validates interrupt-to-thread response time in switch scenarios
 * - Provides quantitative results in microseconds (us)
 *
 * Test Scenarios:
 * - **Thread Switch Simulation**: Two threads alternate using semaphores
 * - **High-Resolution Timing**: Hardware timer measures switch duration
 * - **Stress Cycles**: Repeated switch operations (RT_UTEST_SYS_PERF_TC_COUNT times)
 * - **Priority Handling**: Higher-priority thread execution (THREAD_PRIORITY+1)
 *
 * Verification Metrics:
 * - Switch time within reasonable limits (< 100 us)
 * - Consistent results across multiple test cycles
 * - No memory leaks during test execution
 * - Correct thread priority handling
 *
 * Dependencies:
 * - RT_USING_PERF_TEST must be enabled
 * - RT_USING_UTEST framework must be enabled
 * - Hardware timer support (for high-resolution timing)
 *
 * Expected Results:
 * [  PASSED  ] [ result   ] testcase (core.context_switch)
 * - Performance data printed in structured table format
 * - Final line: "=== Context Switch Test Results End ==="
 * - Test executed via: `utest_run core.context_switch` in msh
 */

#include <rtthread.h>
#include <rthw.h>
#include <rtdevice.h>
#include <utest.h>
#include <utest_assert.h>
#include <perf_tc.h>

static rt_sem_t sem1, sem2;
static rt_sem_t complete_sem = RT_NULL;

static void local_modify_time(rt_perf_t *perf)
{
    if(perf)
        perf->real_time = perf->real_time - perf->tmp_time;
}

static void perf_thread_event1(void *parameter)
{
    while (1)
    {
        rt_sem_take(sem1, RT_WAITING_FOREVER);
        rt_sem_release(sem2);
    }
}

static void perf_thread_event2(void *parameter)
{
    rt_perf_t *perf = (rt_perf_t *)parameter;

    for (rt_uint32_t i = 0; i < RT_UTEST_SYS_PERF_TC_COUNT; i++)
    {
        perf->tmp_time = 0;
        rt_perf_start(perf);
        rt_sem_take(sem2, RT_WAITING_FOREVER);
        rt_sem_release(sem2);
        rt_perf_stop(perf);

        rt_mutex_take(perf->lock,RT_WAITING_FOREVER);
        perf->count -= 1;
        perf->tmp_time = perf->real_time;
        rt_mutex_release(perf->lock);

        rt_perf_start(perf);
        rt_sem_take(sem2, RT_WAITING_FOREVER);
        rt_sem_release(sem1);
        rt_perf_stop(perf);
    }
    rt_sem_release(complete_sem);
}

rt_err_t context_switch_test(rt_perf_t *perf)
{
    rt_thread_t thread1 = RT_NULL;
    rt_thread_t thread2 = RT_NULL;

# if __STDC_VERSION__ >= 199901L
    rt_strcpy(perf->name,__func__);
#else
    rt_strcpy(perf->name,"context_switch_test");
#endif

    perf->local_modify = local_modify_time;
    sem1 = rt_sem_create("sem1", 1, RT_IPC_FLAG_FIFO);
    sem2 = rt_sem_create("sem2", 0, RT_IPC_FLAG_FIFO);
    complete_sem = rt_sem_create("complete_sem", 0, RT_IPC_FLAG_FIFO);

    thread1 = rt_thread_create("perf_thread_event1", perf_thread_event1, perf,
                                THREAD_STACK_SIZE, THREAD_PRIORITY, THREAD_TIMESLICE);
    if (thread1 == RT_NULL)
    {
        LOG_E("perf_thread_event1 create failed.");
        return -RT_ERROR;
    }

    thread2 = rt_thread_create("perf_thread_event2", perf_thread_event2, perf,
                                THREAD_STACK_SIZE, THREAD_PRIORITY + 1, THREAD_TIMESLICE);
    if (thread2 == RT_NULL)
    {
        LOG_E("perf_thread_event2 create failed.");
        return -RT_ERROR;
    }

    rt_thread_startup(thread1);
    rt_thread_startup(thread2);

    rt_sem_take(complete_sem, RT_WAITING_FOREVER);

    rt_perf_dump(perf);
    rt_thread_delete(thread1);
    rt_sem_delete(complete_sem);
    rt_sem_delete(sem1);
    rt_sem_delete(sem2);

    return RT_EOK;
}