| /* nano_int_to_fiber_sem.c - measure switching time from ISR to diff fiber */ |
| |
| /* |
| * Copyright (c) 2012-2014 Wind River Systems, Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /* |
| * DESCRIPTION |
| * This file contains a test which measure switching time from interrupt |
| * handler execution to executing a different fiber than the one which got |
| * interrupted. |
| * The test starts a higher priority fiber (fiberWaiter) which blocks on a |
| * semaphore thus can't run. Then a lower priority fiber (fiberInt) is started |
| * which sets up an interrupt handler and invokes the software interrupt. The |
| * interrupt handler releases the semaphore which enabled the high priority |
| * fiberWaiter to run and exit. The high priority fiber acquire the sema and |
| * read the time. The time delta is measured from the time |
| * semaphore is released in interrup handler to the time fiberWaiter |
| * starts to executing. |
| */ |
| |
| #include "timestamp.h" |
| #include "utils.h" |
| |
| #include <arch/cpu.h> |
| #include <irq_offload.h> |
| |
| #ifndef STACKSIZE |
| #define STACKSIZE 2000 |
| #endif |
| |
| /* stack used by the fibers */ |
| static char __stack waiterStack[STACKSIZE]; |
| static char __stack intStack[STACKSIZE]; |
| |
| /* semaphore taken by waiting fiber ad released by the interrupt handler */ |
| static struct nano_sem testSema; |
| |
| static uint32_t timestamp = 0; |
| |
| /** |
| * |
| * @brief Test ISR used to measure best case interrupt latency |
| * |
| * The interrupt handler gets the second timestamp. |
| * |
| * @return N/A |
| */ |
| static void latencyTestIsr(void *unused) |
| { |
| ARG_UNUSED(unused); |
| |
| nano_isr_sem_give(&testSema); |
| timestamp = TIME_STAMP_DELTA_GET(0); |
| } |
| |
| /** |
| * |
| * @brief Interrupt preparation fiber |
| * |
| * Fiber makes all the test preparations: registers the interrupt handler, |
| * gets the first timestamp and invokes the software interrupt. |
| * |
| * @return N/A |
| */ |
| static void fiberInt(void) |
| { |
| irq_offload(latencyTestIsr, NULL); |
| fiber_yield(); |
| } |
| |
| /** |
| * |
| * @brief Check the time when it gets executed after the semaphore |
| * |
| * Fiber starts, waits on semaphore. When the interrupt handler releases |
| * the semaphore, fiber measures the time. |
| * |
| * @return N/A |
| */ |
| static void fiberWaiter(void) |
| { |
| nano_fiber_sem_take(&testSema, TICKS_UNLIMITED); |
| timestamp = TIME_STAMP_DELTA_GET(timestamp); |
| } |
| |
| /** |
| * |
| * @brief The test main function |
| * |
| * @return 0 on success |
| */ |
| int nanoIntToFiberSem(void) |
| { |
| PRINT_FORMAT(" 3- Measure time from ISR to executing a different fiber" |
| " (rescheduled)"); |
| nano_sem_init(&testSema); |
| |
| TICK_SYNCH(); |
| task_fiber_start(&waiterStack[0], STACKSIZE, |
| (nano_fiber_entry_t) fiberWaiter, 0, 0, 5, 0); |
| task_fiber_start(&intStack[0], STACKSIZE, |
| (nano_fiber_entry_t) fiberInt, 0, 0, 6, 0); |
| |
| PRINT_FORMAT(" switching time is %lu tcs = %lu nsec", |
| timestamp, SYS_CLOCK_HW_CYCLES_TO_NS(timestamp)); |
| return 0; |
| } |