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Update semaphore priority scheduling to use linear search on unordered list w/ S

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Themis Demetriades
2024-10-20 22:50:31 +01:00
parent 840df8af78
commit dae5b0d097
1 changed files with 7 additions and 5 deletions
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12
src/threads/synch.c
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@@ -68,8 +68,7 @@ sema_down (struct semaphore *sema)
old_level = intr_disable (); old_level = intr_disable ();
while (sema->value == 0) while (sema->value == 0)
{ {
list_insert_ordered(&sema->waiters, &thread_current ()->elem, list_push_back (&sema->waiters, &thread_current ()->elem);
priority_more, NULL);
thread_block (); thread_block ();
} }
sema->value--; sema->value--;
@@ -114,9 +113,12 @@ sema_up (struct semaphore *sema)
ASSERT (sema != NULL); ASSERT (sema != NULL);
old_level = intr_disable (); old_level = intr_disable ();
if (!list_empty (&sema->waiters)) if (!list_empty (&sema->waiters))
thread_unblock (list_entry (list_pop_front (&sema->waiters), {
struct thread, elem)); struct list_elem *e = list_min (&sema->waiters, priority_more, NULL);
list_remove (e);
thread_unblock (list_entry (e, struct thread, elem));
}
sema->value++; sema->value++;
intr_set_level (old_level); intr_set_level (old_level);