gh0s7/mckernel
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

futex(): spin wait when CPU not oversubscribed and fix lost wake-up bug

Browse Source
This commit is contained in:
Balazs Gerofi
2017-01-12 18:50:21 +09:00
parent d646c2a4b9
commit bd47b909bf
7 changed files with 163 additions and 142 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
kernel/futex.c
View File

@@ -248,9 +248,13 @@ static int cmpxchg_futex_value_locked(uint32_t __user *uaddr, uint32_t uval, uin
static int get_futex_value_locked(uint32_t *dest, uint32_t *from)
{
/* RIKEN: futexes are always on not swappable pages */
*dest = getint_user((int *)from);
/*
* Officially we should call:
* return getint_user((int *)dest, (int *)from);
*
* but McKernel on x86 can just access user-space.
*/
*dest = *(volatile uint32_t *)from;
return 0;
}
@@ -670,26 +674,32 @@ static uint64_t futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q
uint64_t timeout)
{
uint64_t time_remain = 0;
unsigned long irqstate;
struct thread *thread = cpu_local_var(current);
/*
* The task state is guaranteed to be set before another task can
* wake it. set_current_state() is implemented using set_mb() and
* queue_me() calls spin_unlock() upon completion, both serializing
* access to the hash list and forcing another memory barrier.
* wake it.
* queue_me() calls spin_unlock() upon completion, serializing
* access to the hash list and forcing a memory barrier.
*/
xchg4(&(cpu_local_var(current)->status), PS_INTERRUPTIBLE);
barrier();
/* Indicate spin sleep */
irqstate = ihk_mc_spinlock_lock(&thread->spin_sleep_lock);
thread->spin_sleep = 1;
ihk_mc_spinlock_unlock(&thread->spin_sleep_lock, irqstate);
queue_me(q, hb);
if (!plist_node_empty(&q->list)) {
/* RIKEN: use mcos timers */
if (timeout) {
dkprintf("futex_wait_queue_me(): tid: %d schedule_timeout()\n", cpu_local_var(current)->tid);
time_remain = schedule_timeout(timeout);
}
else {
dkprintf("futex_wait_queue_me(): tid: %d schedule()\n", cpu_local_var(current)->tid);
schedule();
spin_sleep_or_schedule();
time_remain = 0;
}
@@ -698,6 +708,7 @@ static uint64_t futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q
/* This does not need to be serialized */
cpu_local_var(current)->status = PS_RUNNING;
thread->spin_sleep = 0;
return time_remain;
}
@@ -744,14 +755,17 @@ static int futex_wait_setup(uint32_t __user *uaddr, uint32_t val, int fshared,
*/
q->key = FUTEX_KEY_INIT;
ret = get_futex_key(uaddr, fshared, &q->key);
if ((ret != 0))
if (ret != 0)
return ret;
*hb = queue_lock(q);
ret = get_futex_value_locked(&uval, uaddr);
/* RIKEN: get_futex_value_locked() always returns 0 on mckernel */
if (ret) {
queue_unlock(q, *hb);
put_futex_key(fshared, &q->key);
return ret;
}
if (uval != val) {
queue_unlock(q, *hb);
@@ -777,8 +791,6 @@ static int futex_wait(uint32_t __user *uaddr, int fshared,
q.bitset = bitset;
q.requeue_pi_key = NULL;
/* RIKEN: futex_wait_queue_me() calls schedule_timeout() if timer is set */
retry:
/* Prepare to wait on uaddr. */
ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);