- Pass the priority argument from *sleep() into sleepq and down into

   sched_sleep().  This removes extra thread_lock() acquisition and
   allows the scheduler to decide what to do with the static boost.
 - Change the priority arguments to cv_* to match sleepq/msleep/etc.
   where 0 means no priority change.  Catch -1 in cv_broadcastpri() and
   convert it to 0 for now.
 - Set a flag when sleeping in a way that is compatible with swapping
   since direct priority comparisons are meaningless now.
 - Add a sysctl to ule, kern.sched.static_boost, that defaults to on which
   controls the boost behavior.  Turning it off gives better performance
   in some workloads but needs more investigation.
 - While we're modifying sleepq, change signal and broadcast to both
   return with the lock held as the lock was held on enter.

Reviewed by:	jhb, peter

1 files changed, 6 insertions, 1 deletions

diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c
index 834788c..0232e09 100644
--- a/sys/kern/sched_4bsd.c
+++ b/sys/kern/sched_4bsd.c
@@ -799,12 +799,16 @@ sched_unlend_user_prio(struct thread *td, u_char prio)
 }
 
 void
-sched_sleep(struct thread *td)
+sched_sleep(struct thread *td, int pri)
 {
 
 	THREAD_LOCK_ASSERT(td, MA_OWNED);
 	td->td_slptick = ticks;
 	td->td_sched->ts_slptime = 0;
+	if (pri)
+		sched_prio(td, pri);
+	if (TD_IS_SUSPENDED(td) || pri <= PSOCK)
+		td->td_flags |= TDF_CANSWAP;
 }
 
 void
@@ -922,6 +926,7 @@ sched_wakeup(struct thread *td)
 
 	THREAD_LOCK_ASSERT(td, MA_OWNED);
 	ts = td->td_sched;
+	td->td_flags &= ~TDF_CANSWAP;
 	if (ts->ts_slptime > 1) {
 		updatepri(td);
 		resetpriority(td);