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tests: kernel: timer: test delay for schedule in timer callback
This verifies that when a second timer is scheduled within a delayed timer callback the lateness of the callback (as reflected by unprocessed announced ticks) does not impact the timeout of the newly scheduled timer. Relates to issue #12332. Signed-off-by: Peter A. Bigot <[email protected]>
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‎tests/kernel/timer/timer_schedule/CMakeLists.txt

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cmake_minimum_required(VERSION 3.13.1)
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include($ENV{ZEPHYR_BASE}/cmake/app/boilerplate.cmake NO_POLICY_SCOPE)
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project(timer_schedule)
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FILE(GLOB app_sources src/*.c)
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target_sources(app PRIVATE ${app_sources})

‎tests/kernel/timer/timer_schedule/README

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$ make run
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[QEMU] CPU: qemu32
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Running test suite test_timer_api
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tc_start() - test_timer_duration_period
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===================================================================
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PASS - test_timer_duration_period.
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tc_start() - test_timer_period_0
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===================================================================
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PASS - test_timer_period_0.
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tc_start() - test_timer_expirefn_null
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===================================================================
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PASS - test_timer_expirefn_null.
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tc_start() - test_timer_status_get
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===================================================================
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PASS - test_timer_status_get.
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tc_start() - test_timer_status_get_anytime
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===================================================================
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PASS - test_timer_status_get_anytime.
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tc_start() - test_timer_status_sync
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===================================================================
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PASS - test_timer_status_sync.
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tc_start() - test_timer_k_define
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===================================================================
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PASS - test_timer_k_define.
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===================================================================
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PROJECT EXECUTION SUCCESSFUL

‎tests/kernel/timer/timer_schedule/prj.conf

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CONFIG_ZTEST=y
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CONFIG_QEMU_TICKLESS_WORKAROUND=y
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CONFIG_SYS_CLOCK_TICKS_PER_SEC=100

‎tests/kernel/timer/timer_schedule/prj_tickless.conf

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CONFIG_ZTEST=y
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CONFIG_SYS_POWER_MANAGEMENT=y
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CONFIG_TICKLESS_KERNEL=y
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CONFIG_SYS_CLOCK_TICKS_PER_SEC=100

‎tests/kernel/timer/timer_schedule/src/main.c

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/*
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* Copyright (c) 2018 Peter Bigot Consulting, LLC
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/* T1 is a periodic timer with a 100 ms interval. When it fires, it
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* schedules T2 as a one-shot timer due in 50 ms.
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*
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* To produce the theoretical mis-handling we need to construct a
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* situation where tick processing is delayed such that when T1 fires
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* there is at least one tick remaining that is used to prematurely
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* reduce the delay of the T2 that gets scheduled when T1 is
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* processed.
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*
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* We do this by having the main loop wait until T2 fires the 3d time,
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* indicated by a semaphore. When it can take the semaphore it locks
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* interrupt handling for T1's period minus half of T2's timeout,
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* which means the next T1 will fire half T2's timeout late, and the
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* delay for T2 should be reduced by half. It then waits for T2 to
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* run. The delay for T2 will be shorter than in the non-blocking
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* case if the mis-handling occurs.
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*/
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#include <zephyr.h>
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#include <ztest.h>
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#define T1_PERIOD 1000 /* [ms] */
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#define T2_TIMEOUT 50 /* [ms] */
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#define CYC_PER_TICK (CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC \
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/ CONFIG_SYS_CLOCK_TICKS_PER_SEC)
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#define T2_TIMEOUT_TICK (K_MSEC(T2_TIMEOUT) \
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* CONFIG_SYS_CLOCK_TICKS_PER_SEC \
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/ MSEC_PER_SEC)
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static struct k_timer timer1;
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static struct k_timer timer2;
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static struct k_timer sync_timer;
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static struct k_sem semaphore;
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static struct state {
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unsigned int run;
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/** k_uptime_get_32() when T1 last expired */
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u32_t t1_exec_ut;
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/** k_cycle_get_32() when T1 last expired */
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u32_t t1_exec_ct;
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/** Difference in k_cycle_get() between most recent two T1 expires */
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s32_t t1_delay_ct;
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/** Difference in k_uptime_get() between most recent two T1 expires */
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s32_t t1_delay_ut;
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/** Difference in k_cycle_get() between T2 start and callback */
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s32_t t2_delay_ct;
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/** Difference in k_uptime_get() between T2 start and callback */
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s32_t t2_delay_ut;
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/** Tick-corrected measured realtime between T2 start and callback */
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s32_t t2_delay_us;
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} state;
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static void timer1_expire(struct k_timer *timer)
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{
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state.t1_exec_ut = k_uptime_get_32();
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state.t1_exec_ct = k_cycle_get_32();
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k_timer_start(&timer2, K_MSEC(T2_TIMEOUT), 0);
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}
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static void timer2_expire(struct k_timer *timer)
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{
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static u32_t t1_prev_ct;
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static u32_t t1_prev_ut;
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u32_t now_ct = k_cycle_get_32();
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u32_t now_ut = k_uptime_get_32();
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state.t1_delay_ct = state.t1_exec_ct - t1_prev_ct;
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state.t1_delay_ut = state.t1_exec_ut - t1_prev_ut;
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state.t2_delay_ct = now_ct - state.t1_exec_ct;
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state.t2_delay_ut = now_ut - state.t1_exec_ut;
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if (USEC_PER_SEC < sys_clock_hw_cycles_per_sec()) {
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u32_t div = sys_clock_hw_cycles_per_sec()
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/ USEC_PER_SEC;
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state.t2_delay_us = state.t2_delay_ct / div;
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} else {
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state.t2_delay_us = state.t2_delay_ct
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* (u64_t)USEC_PER_SEC
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/ sys_clock_hw_cycles_per_sec();
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}
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t1_prev_ct = state.t1_exec_ct;
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t1_prev_ut = state.t1_exec_ut;
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k_sem_give(&semaphore);
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}
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static void test_schedule(void)
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{
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k_timer_init(&timer1, timer1_expire, NULL);
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k_timer_init(&timer2, timer2_expire, NULL);
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k_sem_init(&semaphore, 0, 1);
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TC_PRINT("T1 interval %u ms, T2 timeout %u ms, %u sysclock per tick\n",
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T1_PERIOD, T2_TIMEOUT, sys_clock_hw_cycles_per_sec());
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k_timer_init(&sync_timer, NULL, NULL);
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k_timer_start(&sync_timer, 0, 1);
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k_timer_status_sync(&sync_timer);
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k_timer_stop(&sync_timer);
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k_timer_start(&timer1, K_MSEC(T1_PERIOD), K_MSEC(T1_PERIOD));
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while (state.run < 6) {
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static s32_t t2_lower_tick = T2_TIMEOUT_TICK - 1;
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static s32_t t2_upper_tick = T2_TIMEOUT_TICK + 1;
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s32_t t2_delay_tick;
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k_sem_take(&semaphore, K_FOREVER);
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if (state.run > 0) {
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t2_delay_tick = state.t2_delay_us
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* (u64_t)CONFIG_SYS_CLOCK_TICKS_PER_SEC
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/ USEC_PER_SEC;
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TC_PRINT("Run %u timer1 last %u interval %d/%d; "
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" timer2 delay %d/%d = %d us = %d tick\n",
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state.run, state.t1_exec_ut,
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state.t1_delay_ct, state.t1_delay_ut,
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state.t2_delay_ct, state.t2_delay_ut,
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state.t2_delay_us, t2_delay_tick);
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zassert_true(t2_delay_tick >= t2_lower_tick,
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"expected delay %d >= %d",
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t2_delay_tick, t2_lower_tick);
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zassert_true(t2_delay_tick <= t2_upper_tick,
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"expected delay %d <= %d",
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t2_delay_tick, t2_upper_tick);
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}
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if (state.run == 3) {
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unsigned int key;
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TC_PRINT("blocking\n");
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key = irq_lock();
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k_busy_wait(K_MSEC(T1_PERIOD - T2_TIMEOUT / 2)
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* USEC_PER_MSEC);
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irq_unlock(key);
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}
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++state.run;
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}
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k_timer_stop(&timer1);
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}
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void test_main(void)
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{
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ztest_test_suite(timer_fn, ztest_unit_test(test_schedule));
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ztest_run_test_suite(timer_fn);
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}

‎tests/kernel/timer/timer_schedule/testcase.yaml

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tests:
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kernel.timer:
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tags: kernel
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arch_exclude: riscv32 nios2 posix
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kernel.timer.tickless:
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build_only: true
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extra_args: CONF_FILE="prj_tickless.conf"
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arch_exclude: riscv32 nios2 posix
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tags: kernel

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