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add mlfqs condition checking in synchronisation primitives

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This commit is contained in:
EDiasAlberto
2024-10-23 19:37:27 +01:00
parent 1fb101c365
commit d8c843f16a
2 changed files with 62 additions and 45 deletions
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101
src/threads/synch.c
View File

@@ -251,19 +251,27 @@ lock_acquire (struct lock *lock)
ASSERT (!lock_held_by_current_thread (lock));
struct thread *t = thread_current ();
enum intr_level old_level = intr_disable ();
if (lock->holder != NULL)
{
t->waiting_lock = lock;
donate_priority (lock->holder);
}
if(!thread_mlfqs)
{
enum intr_level old_level = intr_disable ();
if (lock->holder != NULL)
{
t->waiting_lock = lock;
donate_priority (lock->holder);
}
intr_set_level (old_level);
}
intr_set_level (old_level);
sema_down (&lock->semaphore);
lock->holder = thread_current ();
t->waiting_lock = NULL;
if (!thread_mlfqs)
t->waiting_lock = NULL;
}
/* Tries to acquires LOCK and returns true if successful or false
@@ -297,50 +305,53 @@ lock_release (struct lock *lock)
ASSERT (lock != NULL);
ASSERT (lock_held_by_current_thread (lock));
struct thread *current_thread = thread_current ();
struct thread *max_donor = NULL;
if (!thread_mlfqs)
{
struct thread *current_thread = thread_current ();
struct thread *max_donor = NULL;
struct list orphan_list;
list_init (&orphan_list);
struct list orphan_list;
list_init (&orphan_list);
enum intr_level old_level = intr_disable ();
/* Loop through current thread's donors, removing the ones waiting for the
lock being released and keeping track of them (within orphan_list).
Also identifies the highest priority donor thread among them. */
struct list_elem *tail = list_tail (&current_thread->donors_list);
struct list_elem *e = list_begin (&current_thread->donors_list);
while (e != tail)
{
struct thread *donor = list_entry (e, struct thread, donor_elem);
struct list_elem *next = list_next (e);
enum intr_level old_level = intr_disable ();
/* Loop through current thread's donors, removing the ones waiting for the
lock being released and keeping track of them (within orphan_list).
Also identifies the highest priority donor thread among them. */
struct list_elem *tail = list_tail (&current_thread->donors_list);
struct list_elem *e = list_begin (&current_thread->donors_list);
while (e != tail)
{
struct thread *donor = list_entry (e, struct thread, donor_elem);
struct list_elem *next = list_next (e);
/* Excludes donors that aren't waiting for the lock being released,
and tracks the rest. */
if (donor->waiting_lock == lock)
{
list_remove (e);
list_push_back (&orphan_list, e);
/* Excludes donors that aren't waiting for the lock being released,
and tracks the rest. */
if (donor->waiting_lock == lock)
{
list_remove (e);
list_push_back (&orphan_list, e);
/* Identify highest priority donor. */
if (max_donor == NULL || donor->priority > max_donor->priority)
max_donor = donor;
}
/* Identify highest priority donor. */
if (max_donor == NULL || donor->priority > max_donor->priority)
max_donor = donor;
}
e = next;
}
e = next;
}
/* If there exists a maximum donor thread waiting for this lock to be
released, transfer the remaining orphaned donors to its donor list. */
if (max_donor != NULL)
{
while (!list_empty (&orphan_list))
list_push_back (&max_donor->donors_list, list_pop_front (&orphan_list));
}
/* If there exists a maximum donor thread waiting for this lock to be
released, transfer the remaining orphaned donors to its donor list. */
if (max_donor != NULL)
{
while (!list_empty (&orphan_list))
list_push_back (&max_donor->donors_list, list_pop_front (&orphan_list));
}
intr_set_level (old_level);
/* Removal of donors to this thread may change its effective priority,
so recalculate. */
thread_recalculate_priority ();
intr_set_level (old_level);
/* Removal of donors to this thread may change its effective priority,
so recalculate. */
thread_recalculate_priority ();
}
lock->holder = NULL;
sema_up (&lock->semaphore);

6
src/threads/thread.c
View File

@@ -474,6 +474,12 @@ thread_recalculate_priority (void)
{
struct thread *t = thread_current ();
if (thread_mlfqs)
{
t->priority = calculate_bsd_priority (t->recent_cpu, t->nice);
return;
}
enum intr_level old_level = intr_disable ();
t->priority = t->base_priority;