- Optimize wakeup() and its friends; if a thread waken up is being

  swapped in, we do not have to ask for the scheduler thread to do
  that.

- Assert that a process is not swapped out in runq functions and
  swapout().

- Introduce thread_safetoswapout() for readability.

- In swapout_procs(), perform a test that may block (check of a
  thread working on its vm map) first.  This lets us call swapout()
  with the sched_lock held, providing a better atomicity.

3 files changed, 22 insertions, 8 deletions

diff --git a/sys/kern/kern_condvar.c b/sys/kern/kern_condvar.c
index 822a4c9..55fba60 100644
--- a/sys/kern/kern_condvar.c
+++ b/sys/kern/kern_condvar.c
@@ -534,8 +534,10 @@ cv_wakeup(struct cv *cvp)
 			maybe_resched(td);
 		} else {
 			td->td_state = TDS_SWAPPED;
-			td->td_proc->p_sflag |= PS_SWAPINREQ;
-			wakeup(&proc0); /* XXXKSE */
+			if ((td->td_proc->p_sflag & PS_SWAPPINGIN) == 0) {
+				td->td_proc->p_sflag |= PS_SWAPINREQ;
+				wakeup(&proc0);
+			}
 		}
 		/* END INLINE EXPANSION */
 	}
diff --git a/sys/kern/kern_switch.c b/sys/kern/kern_switch.c
index 9629ac2..97dd771 100644
--- a/sys/kern/kern_switch.c
+++ b/sys/kern/kern_switch.c
@@ -525,6 +525,8 @@ runq_add(struct runq *rq, struct kse *ke)
 	KASSERT(ke->ke_state != KES_ONRUNQ,
 	    ("runq_add: kse %p (%s) already in run queue", ke,
 	    ke->ke_proc->p_comm));
+	KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
+		("runq_add: process swapped out"));
 	pri = ke->ke_thread->td_priority / RQ_PPQ;
 	ke->ke_rqindex = pri;
 	runq_setbit(rq, pri);
@@ -590,6 +592,8 @@ runq_choose(struct runq *rq)
 		    ("runq_choose: No thread on KSE"));
 		KASSERT((ke->ke_thread->td_kse != NULL),
 		    ("runq_choose: No KSE on thread"));
+		KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
+			("runq_choose: process swapped out"));
 		return (ke);
 	}
 	CTR1(KTR_RUNQ, "runq_choose: idleproc pri=%d", pri);
@@ -610,6 +614,8 @@ runq_remove(struct runq *rq, struct kse *ke)
 
 	KASSERT((ke->ke_state == KES_ONRUNQ), ("KSE not on run queue"));
 	mtx_assert(&sched_lock, MA_OWNED);
+	KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
+		("runq_remove: process swapped out"));
 	pri = ke->ke_rqindex;
 	rqh = &rq->rq_queues[pri];
 	CTR4(KTR_RUNQ, "runq_remove: p=%p pri=%d %d rqh=%p",
diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index e4bef85..9e60459 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -719,8 +719,10 @@ restart:
 					maybe_resched(td);
 				} else {
 					td->td_state = TDS_SWAPPED;
-					p->p_sflag |= PS_SWAPINREQ;
-					wakeup(&proc0);
+					if ((p->p_sflag & PS_SWAPPINGIN) == 0) {
+						p->p_sflag |= PS_SWAPINREQ;
+						wakeup(&proc0);
+					}
 				}
 				/* END INLINE EXPANSION */
 			}
@@ -766,8 +768,10 @@ restart:
 					break;
 				} else {
 					td->td_state = TDS_SWAPPED;
-					p->p_sflag |= PS_SWAPINREQ;
-					wakeup(&proc0);
+					if ((p->p_sflag & PS_SWAPPINGIN) == 0) {
+						p->p_sflag |= PS_SWAPINREQ;
+						wakeup(&proc0);
+					}
 				}
 				/* END INLINE EXPANSION */
 				goto restart;
@@ -941,8 +945,10 @@ setrunnable(struct thread *td)
 	td->td_ksegrp->kg_slptime = 0;
 	if ((p->p_sflag & PS_INMEM) == 0) {
 		td->td_state = TDS_SWAPPED;
-		p->p_sflag |= PS_SWAPINREQ;
-		wakeup(&proc0);
+		if ((p->p_sflag & PS_SWAPPINGIN) == 0) {
+			p->p_sflag |= PS_SWAPINREQ;
+			wakeup(&proc0);
+		}
 	} else {
 		if (td->td_state != TDS_RUNQ)
 			setrunqueue(td); /* XXXKSE */