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[kernel][thread] Wake up only needed cores

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This change ensures that during thread scheduling
only needed cores are woken up as per the thread's
CPU affinity rather than all cores. This would avoid
un-necessary wakup for other cores from lower power
states without having to execute anything.

Signed-off-by: vannapurve <vannapurve@google.com>
This commit is contained in:
vannapurve
2020-07-21 16:51:56 +05:30
committed by Travis Geiselbrecht
parent c4cdc17865
commit 961ef679cf
1 changed files with 22 additions and 6 deletions
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28
kernel/thread.c
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@@ -97,6 +97,16 @@ static void insert_in_run_queue_tail(thread_t *t) {
run_queue_bitmap |= (1<<t->priority);
}
static void wakeup_cpu_for_thread(thread_t *t)
{
/* Wake up the core to which this thread is pinned
* or wake up all if thread is unpinned */
if (thread_pinned_cpu(t) < 0)
mp_reschedule(MP_CPU_ALL_BUT_LOCAL, 0);
else
mp_reschedule(1U << thread_pinned_cpu(t), 0);
}
void init_thread_struct(thread_t *t, const char *name) {
memset(t, 0, sizeof(thread_t));
t->magic = THREAD_MAGIC;
@@ -274,7 +284,7 @@ status_t thread_resume(thread_t *t) {
resched = true;
}
mp_reschedule(MP_CPU_ALL_BUT_LOCAL, 0);
wakeup_cpu_for_thread(t);
THREAD_UNLOCK(state);
@@ -685,7 +695,8 @@ void thread_unblock(thread_t *t, bool resched) {
t->state = THREAD_READY;
insert_in_run_queue_head(t);
mp_reschedule(MP_CPU_ALL_BUT_LOCAL, 0);
wakeup_cpu_for_thread(t);
if (resched)
thread_resched();
}
@@ -1116,7 +1127,7 @@ int wait_queue_wake_one(wait_queue_t *wait, bool reschedule, status_t wait_queue
insert_in_run_queue_head(current_thread);
}
insert_in_run_queue_head(t);
mp_reschedule(MP_CPU_ALL_BUT_LOCAL, 0);
wakeup_cpu_for_thread(t);
if (reschedule) {
thread_resched();
}
@@ -1145,6 +1156,7 @@ int wait_queue_wake_one(wait_queue_t *wait, bool reschedule, status_t wait_queue
int wait_queue_wake_all(wait_queue_t *wait, bool reschedule, status_t wait_queue_error) {
thread_t *t;
int ret = 0;
uint32_t cpu_mask = 0;
thread_t *current_thread = get_current_thread();
@@ -1168,7 +1180,11 @@ int wait_queue_wake_all(wait_queue_t *wait, bool reschedule, status_t wait_queue
t->state = THREAD_READY;
t->wait_queue_block_ret = wait_queue_error;
t->blocking_wait_queue = NULL;
if (thread_pinned_cpu(t) < 0) {
cpu_mask = MP_CPU_ALL_BUT_LOCAL;
} else {
cpu_mask |= (1U << thread_pinned_cpu(t));
}
insert_in_run_queue_head(t);
ret++;
}
@@ -1176,7 +1192,7 @@ int wait_queue_wake_all(wait_queue_t *wait, bool reschedule, status_t wait_queue
DEBUG_ASSERT(wait->count == 0);
if (ret > 0) {
mp_reschedule(MP_CPU_ALL_BUT_LOCAL, 0);
mp_reschedule(cpu_mask, 0);
if (reschedule) {
thread_resched();
}
@@ -1229,7 +1245,7 @@ status_t thread_unblock_from_wait_queue(thread_t *t, status_t wait_queue_error)
t->state = THREAD_READY;
t->wait_queue_block_ret = wait_queue_error;
insert_in_run_queue_head(t);
mp_reschedule(MP_CPU_ALL_BUT_LOCAL, 0);
wakeup_cpu_for_thread(t);
return NO_ERROR;
}