- 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.

1 files changed, 12 insertions, 6 deletions

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 */