MFp4:

- Add flags CVWAIT_ABSTIME and CVWAIT_CLOCKID for umtx kernel based
  condition variable, this should eliminate an extra system call to get
  current time.

- Add sub-function UMTX_OP_NWAKE_PRIVATE to wake up N channels in single
  system call. Create userland sleep queue for condition variable, in most
  cases, thread will wait in the queue, the pthread_cond_signal will defer
  thread wakeup until the mutex is unlocked, it tries to avoid an extra
  system call and a extra context switch in time window of pthread_cond_signal
  and pthread_mutex_unlock.

The changes are part of process-shared mutex project.

1 files changed, 53 insertions, 0 deletions

diff --git a/lib/libthr/thread/thr_umtx.c b/lib/libthr/thread/thr_umtx.c
index dabfa35..33c3637 100644
--- a/lib/libthr/thread/thr_umtx.c
+++ b/lib/libthr/thread/thr_umtx.c
@@ -74,6 +74,39 @@ __thr_umutex_lock(struct umutex *mtx, uint32_t id)
 	return	_umtx_op_err(mtx, UMTX_OP_MUTEX_LOCK, 0, 0, 0);
 }
 
+#define SPINLOOPS 1000
+
+int
+__thr_umutex_lock_spin(struct umutex *mtx, uint32_t id)
+{
+	uint32_t owner;
+
+	if (!_thr_is_smp)
+		return __thr_umutex_lock(mtx, id);
+
+	if ((mtx->m_flags & (UMUTEX_PRIO_PROTECT | UMUTEX_PRIO_INHERIT)) == 0) {
+		for (;;) {
+			int count = SPINLOOPS;
+			while (count--) {
+				owner = mtx->m_owner;
+				if ((owner & ~UMUTEX_CONTESTED) == 0) {
+					if (atomic_cmpset_acq_32(
+					    &mtx->m_owner,
+					    owner, id|owner)) {
+						return (0);
+					}
+				}
+				CPU_SPINWAIT;
+			}
+
+			/* wait in kernel */
+			_umtx_op_err(mtx, UMTX_OP_MUTEX_WAIT, 0, 0, 0);
+		}
+	}
+
+	return	_umtx_op_err(mtx, UMTX_OP_MUTEX_LOCK, 0, 0, 0);
+}
+
 int
 __thr_umutex_timedlock(struct umutex *mtx, uint32_t id,
 	const struct timespec *ets)
@@ -164,6 +197,26 @@ _thr_umtx_wait_uint(volatile u_int *mtx, u_int id, const struct timespec *timeou
 }
 
 int
+_thr_umtx_timedwait_uint(volatile u_int *mtx, u_int id, int clockid,
+	const struct timespec *abstime, int shared)
+{
+	struct timespec ts, ts2, *tsp;
+
+	if (abstime != NULL) {
+		clock_gettime(clockid, &ts);
+		TIMESPEC_SUB(&ts2, abstime, &ts);
+		if (ts2.tv_sec < 0 || ts2.tv_nsec <= 0)
+			return (ETIMEDOUT);
+		tsp = &ts2;
+	} else {
+		tsp = NULL;
+	}
+	return _umtx_op_err(__DEVOLATILE(void *, mtx), 
+		shared ? UMTX_OP_WAIT_UINT : UMTX_OP_WAIT_UINT_PRIVATE, id, NULL,
+			tsp);
+}
+
+int
 _thr_umtx_wake(volatile void *mtx, int nr_wakeup, int shared)
 {
 	return _umtx_op_err(__DEVOLATILE(void *, mtx), shared ? UMTX_OP_WAKE : UMTX_OP_WAKE_PRIVATE,