59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
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/* Checks that when the alarm clock wakes up threads, the
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higher-priority threads run first. */
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#include <stdio.h>
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#include "tests/threads/tests.h"
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#include "threads/init.h"
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#include "threads/malloc.h"
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#include "threads/synch.h"
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#include "threads/thread.h"
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#include "devices/timer.h"
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static thread_func alarm_priority_thread;
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static int64_t wake_time;
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static struct semaphore wait_sema;
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void
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test_alarm_priority (void)
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{
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int i;
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/* This test does not work with the MLFQS. */
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ASSERT (!thread_mlfqs);
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wake_time = timer_ticks () + 5 * TIMER_FREQ;
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sema_init (&wait_sema, 0);
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for (i = 0; i < 10; i++)
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{
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int priority = PRI_DEFAULT - (i + 5) % 10 - 1;
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char name[16];
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snprintf (name, sizeof name, "priority %d", priority);
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thread_create (name, priority, alarm_priority_thread, NULL);
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}
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thread_set_priority (PRI_MIN);
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for (i = 0; i < 10; i++)
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sema_down (&wait_sema);
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}
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static void
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alarm_priority_thread (void *aux UNUSED)
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{
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/* Busy-wait until the current time changes. */
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int64_t start_time = timer_ticks ();
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while (timer_elapsed (start_time) == 0)
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continue;
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/* Now we know we're at the very beginning of a timer tick, so
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we can call timer_sleep() without worrying about races
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between checking the time and a timer interrupt. */
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timer_sleep (wake_time - timer_ticks ());
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/* Print a message on wake-up. */
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msg ("Thread %s woke up.", thread_name ());
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sema_up (&wait_sema);
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}
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