- Set the priority of the page zeroing thread using sched_prio() when the

  thread is created rather than adjusting the priority in the main
  function.  (kthread_create() should probably take the initial priority
  as an argument.)
- Only yield the CPU in the !PREEMPTION case if there are any other
  runnable threads.  Yielding when there isn't anything else better to do
  just wastes time in pointless context switches (albeit while the system
  is idle.)

1 files changed, 5 insertions, 14 deletions

diff --git a/sys/vm/vm_zeroidle.c b/sys/vm/vm_zeroidle.c
index 9abd5f1..2609c2d 100644
--- a/sys/vm/vm_zeroidle.c
+++ b/sys/vm/vm_zeroidle.c
@@ -141,36 +141,26 @@ vm_page_zero_idle_wakeup(void)
 static void
 vm_pagezero(void __unused *arg)
 {
-	struct rtprio rtp;
 	struct thread *td;
-	int pages, pri;
 
 	td = curthread;
-	rtp.prio = RTP_PRIO_MAX;
-	rtp.type = RTP_PRIO_IDLE;
-	pages = 0;
-	mtx_lock_spin(&sched_lock);
-	rtp_to_pri(&rtp, td->td_ksegrp);
-	pri = td->td_priority;
-	mtx_unlock_spin(&sched_lock);
 	idlezero_enable = idlezero_enable_default;
 
 	for (;;) {
 		if (vm_page_zero_check()) {
-			pages += vm_page_zero_idle();
+			vm_page_zero_idle();
 #ifndef PREEMPTION
-			if (pages > idlezero_maxrun || sched_runnable()) {
+			if (sched_runnable()) {
 				mtx_lock_spin(&sched_lock);
 				mi_switch(SW_VOL, NULL);
 				mtx_unlock_spin(&sched_lock);
-				pages = 0;
 			}
 #endif
 		} else {
 			vm_page_lock_queues();
 			wakeup_needed = TRUE;
-			msleep(&zero_state, &vm_page_queue_mtx, PDROP | pri,
-			    "pgzero", hz * 300);
+			msleep(&zero_state, &vm_page_queue_mtx,
+			    PDROP | td->td_priority, "pgzero", hz * 300);
 			pages = 0;
 		}
 	}
@@ -194,6 +184,7 @@ pagezero_start(void __unused *arg)
 	pagezero_proc->p_flag |= P_NOLOAD;
 	PROC_UNLOCK(pagezero_proc);
 	mtx_lock_spin(&sched_lock);
+	sched_prio(FIRST_THREAD_IN_PROC(pagezero_proc), PRI_MAX_IDLE);
 	setrunqueue(FIRST_THREAD_IN_PROC(pagezero_proc), SRQ_BORING);
 	mtx_unlock_spin(&sched_lock);
 }