diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -14295,7 +14295,7 @@
 
 	CTL_DEBUG_PRINT(("ctl_work_thread starting\n"));
 	thread_lock(curthread);
-	sched_prio(curthread, PUSER - 1);
+	sched_prio(curthread, PRI_MAX_KERN);
 	thread_unlock(curthread);
 
 	while (!softc->shutdown) {
@@ -14387,7 +14387,7 @@
 
 	CTL_DEBUG_PRINT(("ctl_thresh_thread starting\n"));
 	thread_lock(curthread);
-	sched_prio(curthread, PUSER - 1);
+	sched_prio(curthread, PRI_MAX_KERN);
 	thread_unlock(curthread);
 
 	while (!softc->shutdown) {
diff --git a/sys/contrib/openzfs/include/os/freebsd/spl/sys/proc.h b/sys/contrib/openzfs/include/os/freebsd/spl/sys/proc.h
--- a/sys/contrib/openzfs/include/os/freebsd/spl/sys/proc.h
+++ b/sys/contrib/openzfs/include/os/freebsd/spl/sys/proc.h
@@ -44,7 +44,9 @@
 #ifdef _KERNEL
 #define	CPU		curcpu
 #define	minclsyspri	PRIBIO
-#define	defclsyspri minclsyspri
+#define	defclsyspri	minclsyspri
+/* Write issue taskq priority. */
+#define	wtqclsyspri	((PVM + PRIBIO) / 2)
 #define	maxclsyspri	PVM
 #define	max_ncpus	(mp_maxid + 1)
 #define	boot_max_ncpus	(mp_maxid + 1)
diff --git a/sys/contrib/openzfs/include/os/linux/spl/sys/sysmacros.h b/sys/contrib/openzfs/include/os/linux/spl/sys/sysmacros.h
--- a/sys/contrib/openzfs/include/os/linux/spl/sys/sysmacros.h
+++ b/sys/contrib/openzfs/include/os/linux/spl/sys/sysmacros.h
@@ -91,8 +91,10 @@
  * Treat shim tasks as SCHED_NORMAL tasks
  */
 #define	minclsyspri			(MAX_PRIO-1)
-#define	maxclsyspri			(MAX_RT_PRIO)
 #define	defclsyspri			(DEFAULT_PRIO)
+/* Write issue taskq priority. */
+#define	wtqclsyspri			(MAX_RT_PRIO + 1)
+#define	maxclsyspri			(MAX_RT_PRIO)
 
 #ifndef NICE_TO_PRIO
 #define	NICE_TO_PRIO(nice)		(MAX_RT_PRIO + (nice) + 20)
diff --git a/sys/contrib/openzfs/include/sys/zfs_context.h b/sys/contrib/openzfs/include/sys/zfs_context.h
--- a/sys/contrib/openzfs/include/sys/zfs_context.h
+++ b/sys/contrib/openzfs/include/sys/zfs_context.h
@@ -622,8 +622,10 @@
  * Process priorities as defined by setpriority(2) and getpriority(2).
  */
 #define	minclsyspri	19
-#define	maxclsyspri	-20
 #define	defclsyspri	0
+/* Write issue taskq priority. */
+#define	wtqclsyspri	-19
+#define	maxclsyspri	-20
 
 #define	CPU_SEQID	((uintptr_t)pthread_self() & (max_ncpus - 1))
 #define	CPU_SEQID_UNSTABLE	CPU_SEQID
diff --git a/sys/contrib/openzfs/module/zfs/spa.c b/sys/contrib/openzfs/module/zfs/spa.c
--- a/sys/contrib/openzfs/module/zfs/spa.c
+++ b/sys/contrib/openzfs/module/zfs/spa.c
@@ -1222,29 +1222,14 @@
 			    spa->spa_proc, zio_taskq_basedc, flags);
 		} else {
 #endif
-			pri_t pri = maxclsyspri;
 			/*
 			 * The write issue taskq can be extremely CPU
 			 * intensive.  Run it at slightly less important
 			 * priority than the other taskqs.
-			 *
-			 * Under Linux and FreeBSD this means incrementing
-			 * the priority value as opposed to platforms like
-			 * illumos where it should be decremented.
-			 *
-			 * On FreeBSD, if priorities divided by four (RQ_PPQ)
-			 * are equal then a difference between them is
-			 * insignificant.
 			 */
-			if (t == ZIO_TYPE_WRITE && q == ZIO_TASKQ_ISSUE) {
-#if defined(__linux__)
-				pri++;
-#elif defined(__FreeBSD__)
-				pri += 4;
-#else
-#error "unknown OS"
-#endif
-			}
+			const pri_t pri = (t == ZIO_TYPE_WRITE &&
+			    q == ZIO_TASKQ_ISSUE) ?
+			    wtqclsyspri : maxclsyspri;
 			tq = taskq_create_proc(name, value, pri, 50,
 			    INT_MAX, spa->spa_proc, flags);
 #ifdef HAVE_SYSDC
diff --git a/sys/dev/beri/beri_ring.c b/sys/dev/beri/beri_ring.c
--- a/sys/dev/beri/beri_ring.c
+++ b/sys/dev/beri/beri_ring.c
@@ -170,7 +170,7 @@
 	}
 
 	mtx_lock(&sc->beri_mtx);
-	selwakeuppri(&sc->beri_rsel, PZERO + 1);
+	selwakeuppri(&sc->beri_rsel, PZERO);
 	KNOTE_LOCKED(&sc->beri_rsel.si_note, 0);
 	mtx_unlock(&sc->beri_mtx);
 }
@@ -190,7 +190,7 @@
 	}
 
 	mtx_lock(&sc->beri_mtx);
-	selwakeuppri(&sc->beri_rsel, PZERO + 1);
+	selwakeuppri(&sc->beri_rsel, PZERO);
 	KNOTE_LOCKED(&sc->beri_rsel.si_note, 0);
 	mtx_unlock(&sc->beri_mtx);
 }
diff --git a/sys/dev/firewire/firewirereg.h b/sys/dev/firewire/firewirereg.h
--- a/sys/dev/firewire/firewirereg.h
+++ b/sys/dev/firewire/firewirereg.h
@@ -293,7 +293,7 @@
 extern devclass_t firewire_devclass;
 extern int firewire_phydma_enable;
 
-#define	FWPRI		((PZERO + 8) | PCATCH)
+#define	FWPRI		(PWAIT | PCATCH)
 
 #define CALLOUT_INIT(x) callout_init(x, 1 /* mpsafe */)
 
diff --git a/sys/dev/syscons/syscons.c b/sys/dev/syscons/syscons.c
--- a/sys/dev/syscons/syscons.c
+++ b/sys/dev/syscons/syscons.c
@@ -1310,7 +1310,7 @@
 		if (i == sc->cur_scp->index)
 			return 0;
 		error =
-		    tsleep(VTY_WCHAN(sc, i), (PZERO + 1) | PCATCH, "waitvt", 0);
+		    tsleep(VTY_WCHAN(sc, i), PZERO | PCATCH, "waitvt", 0);
 		return error;
 
 	case VT_GETACTIVE: /* get active vty # */
diff --git a/sys/dev/vkbd/vkbd.c b/sys/dev/vkbd/vkbd.c
--- a/sys/dev/vkbd/vkbd.c
+++ b/sys/dev/vkbd/vkbd.c
@@ -82,7 +82,7 @@
 #define VKBD_UNLOCK(s)		mtx_unlock(&(s)->ks_lock)
 #define VKBD_LOCK_ASSERT(s, w)	mtx_assert(&(s)->ks_lock, w)
 #define VKBD_SLEEP(s, f, d, t) \
-	msleep(&(s)->f, &(s)->ks_lock, PCATCH | (PZERO + 1), d, t)
+	msleep(&(s)->f, &(s)->ks_lock, PCATCH | PZERO, d, t)
 #else
 #define VKBD_LOCK_DECL
 #define VKBD_LOCK_INIT(s)
@@ -90,7 +90,7 @@
 #define VKBD_LOCK(s)
 #define VKBD_UNLOCK(s)
 #define VKBD_LOCK_ASSERT(s, w)
-#define VKBD_SLEEP(s, f, d, t)	tsleep(&(s)->f, PCATCH | (PZERO + 1), d, t)
+#define VKBD_SLEEP(s, f, d, t)	tsleep(&(s)->f, PCATCH | PZERO, d, t)
 #endif
 
 #define VKBD_KEYBOARD(d) \
@@ -268,8 +268,8 @@
 		VKBD_SLEEP(state, ks_task, "vkbdc", 0);
 
 	/* wakeup poll()ers */
-	selwakeuppri(&state->ks_rsel, PZERO + 1);
-	selwakeuppri(&state->ks_wsel, PZERO + 1);
+	selwakeuppri(&state->ks_rsel, PZERO);
+	selwakeuppri(&state->ks_wsel, PZERO);
 
 	state->ks_flags &= ~OPEN;
 	state->ks_dev = NULL;
@@ -498,7 +498,7 @@
 
 	if (!(state->ks_flags & STATUS)) {
 		state->ks_flags |= STATUS;
-		selwakeuppri(&state->ks_rsel, PZERO + 1);
+		selwakeuppri(&state->ks_rsel, PZERO);
 		wakeup(&state->ks_flags);
 	}
 }
@@ -531,7 +531,7 @@
 		q->head = 0;
 
 	/* wakeup ks_inq writers/poll()ers */
-	selwakeuppri(&state->ks_wsel, PZERO + 1);
+	selwakeuppri(&state->ks_wsel, PZERO);
 	wakeup(q);
 
 	return (c);
@@ -1246,7 +1246,7 @@
 
 	/* flush ks_inq and wakeup writers/poll()ers */
 	state->ks_inq.head = state->ks_inq.tail = state->ks_inq.cc = 0;
-	selwakeuppri(&state->ks_wsel, PZERO + 1);
+	selwakeuppri(&state->ks_wsel, PZERO);
 	wakeup(&state->ks_inq);
 }
 
diff --git a/sys/fs/fuse/fuse_device.c b/sys/fs/fuse/fuse_device.c
--- a/sys/fs/fuse/fuse_device.c
+++ b/sys/fs/fuse/fuse_device.c
@@ -152,7 +152,7 @@
 	FUSE_LOCK();
 	fuse_lck_mtx_lock(fdata->aw_mtx);
 	/* wakup poll()ers */
-	selwakeuppri(&fdata->ks_rsel, PZERO + 1);
+	selwakeuppri(&fdata->ks_rsel, PZERO);
 	/* Don't let syscall handlers wait in vain */
 	while ((tick = fuse_aw_pop(fdata))) {
 		fuse_lck_mtx_lock(tick->tk_aw_mtx);
diff --git a/sys/fs/fuse/fuse_io.c b/sys/fs/fuse/fuse_io.c
--- a/sys/fs/fuse/fuse_io.c
+++ b/sys/fs/fuse/fuse_io.c
@@ -932,7 +932,7 @@
 		if (vp->v_mount->mnt_kern_flag & MNTK_UNMOUNTF)
 			return EIO;
 		fvdat->flag |= FN_FLUSHWANT;
-		tsleep(&fvdat->flag, PRIBIO + 2, "fusevinv", 2 * hz);
+		tsleep(&fvdat->flag, PRIBIO, "fusevinv", 2 * hz);
 		error = 0;
 		if (p != NULL) {
 			PROC_LOCK(p);
diff --git a/sys/fs/fuse/fuse_ipc.c b/sys/fs/fuse/fuse_ipc.c
--- a/sys/fs/fuse/fuse_ipc.c
+++ b/sys/fs/fuse/fuse_ipc.c
@@ -593,7 +593,7 @@
 	fuse_lck_mtx_lock(data->ms_mtx);
 	data->dataflags |= FSESS_DEAD;
 	wakeup_one(data);
-	selwakeuppri(&data->ks_rsel, PZERO + 1);
+	selwakeuppri(&data->ks_rsel, PZERO);
 	wakeup(&data->ticketer);
 	fuse_lck_mtx_unlock(data->ms_mtx);
 	FUSE_UNLOCK();
@@ -669,7 +669,7 @@
 	else
 		fuse_ms_push(ftick);
 	wakeup_one(ftick->tk_data);
-	selwakeuppri(&ftick->tk_data->ks_rsel, PZERO + 1);
+	selwakeuppri(&ftick->tk_data->ks_rsel, PZERO);
 	KNOTE_LOCKED(&ftick->tk_data->ks_rsel.si_note, 0);
 	fuse_lck_mtx_unlock(ftick->tk_data->ms_mtx);
 }
diff --git a/sys/fs/nfs/nfs_commonsubs.c b/sys/fs/nfs/nfs_commonsubs.c
--- a/sys/fs/nfs/nfs_commonsubs.c
+++ b/sys/fs/nfs/nfs_commonsubs.c
@@ -4662,7 +4662,7 @@
 		ts.tv_sec = 0;
 		ts.tv_nsec = 0;
 		(void) nfsmsleep((caddr_t)flagp, NFSSOCKMUTEXPTR,
-		    PZERO - 1, "nfsndlck", &ts);
+		    PVFS, "nfsndlck", &ts);
 	}
 	*flagp |= NFSR_SNDLOCK;
 	NFSUNLOCKSOCK();
diff --git a/sys/fs/nfsserver/nfs_nfsdcache.c b/sys/fs/nfsserver/nfs_nfsdcache.c
--- a/sys/fs/nfsserver/nfs_nfsdcache.c
+++ b/sys/fs/nfsserver/nfs_nfsdcache.c
@@ -392,7 +392,7 @@
 		nfsaddr_match(NETFAMILY(rp), &rp->rc_haddr, nd->nd_nam)) {
 			if ((rp->rc_flag & RC_LOCKED) != 0) {
 				rp->rc_flag |= RC_WANTED;
-				(void)mtx_sleep(rp, mutex, (PZERO - 1) | PDROP,
+				(void)mtx_sleep(rp, mutex, PVFS | PDROP,
 				    "nfsrc", 10 * hz);
 				goto loop;
 			}
@@ -678,7 +678,7 @@
 		rp = hitrp;
 		if ((rp->rc_flag & RC_LOCKED) != 0) {
 			rp->rc_flag |= RC_WANTED;
-			(void)mtx_sleep(rp, mutex, (PZERO - 1) | PDROP,
+			(void)mtx_sleep(rp, mutex, PVFS | PDROP,
 			    "nfsrc", 10 * hz);
 			goto tryagain;
 		}
@@ -750,7 +750,7 @@
 	mtx_assert(mutex, MA_OWNED);
 	while ((rp->rc_flag & RC_LOCKED) != 0) {
 		rp->rc_flag |= RC_WANTED;
-		(void)mtx_sleep(rp, mutex, PZERO - 1, "nfsrc", 0);
+		(void)mtx_sleep(rp, mutex, PVFS, "nfsrc", 0);
 	}
 	rp->rc_flag |= RC_LOCKED;
 }
diff --git a/sys/fs/nfsserver/nfs_nfsdstate.c b/sys/fs/nfsserver/nfs_nfsdstate.c
--- a/sys/fs/nfsserver/nfs_nfsdstate.c
+++ b/sys/fs/nfsserver/nfs_nfsdstate.c
@@ -552,7 +552,7 @@
 		 */
 		while (clp->lc_cbref) {
 			clp->lc_flags |= LCL_WAKEUPWANTED;
-			(void)mtx_sleep(clp, NFSSTATEMUTEXPTR, PZERO - 1,
+			(void)mtx_sleep(clp, NFSSTATEMUTEXPTR, PVFS,
 			    "nfsd clp", 10 * hz);
 		}
 		NFSUNLOCKSTATE();
@@ -629,7 +629,7 @@
 			NFSLOCKSTATE();
 		while (clp->lc_cbref) {
 			clp->lc_flags |= LCL_WAKEUPWANTED;
-			(void)mtx_sleep(clp, NFSSTATEMUTEXPTR, PZERO - 1,
+			(void)mtx_sleep(clp, NFSSTATEMUTEXPTR, PVFS,
 			    "nfsdclp", 10 * hz);
 		}
 		NFSUNLOCKSTATE();
diff --git a/sys/fs/smbfs/smbfs_io.c b/sys/fs/smbfs/smbfs_io.c
--- a/sys/fs/smbfs/smbfs_io.c
+++ b/sys/fs/smbfs/smbfs_io.c
@@ -629,7 +629,7 @@
 
 	while (np->n_flag & NFLUSHINPROG) {
 		np->n_flag |= NFLUSHWANT;
-		error = tsleep(&np->n_flag, PRIBIO + 2, "smfsvinv", 2 * hz);
+		error = tsleep(&np->n_flag, PRIBIO, "smfsvinv", 2 * hz);
 		error = smb_td_intr(td);
 		if (error == EINTR)
 			return EINTR;
diff --git a/sys/kern/kern_rmlock.c b/sys/kern/kern_rmlock.c
--- a/sys/kern/kern_rmlock.c
+++ b/sys/kern/kern_rmlock.c
@@ -1010,7 +1010,8 @@
 
 	mtx_lock(&rms->mtx);
 	while (rms->writers > 0)
-		msleep(&rms->readers, &rms->mtx, PUSER - 1, mtx_name(&rms->mtx), 0);
+		msleep(&rms->readers, &rms->mtx, PRI_MAX_KERN,
+		    mtx_name(&rms->mtx), 0);
 	critical_enter();
 	rms_int_readers_inc(rms, rms_int_pcpu(rms));
 	mtx_unlock(&rms->mtx);
@@ -1197,7 +1198,7 @@
 	mtx_lock(&rms->mtx);
 	rms->writers++;
 	if (rms->writers > 1) {
-		msleep(&rms->owner, &rms->mtx, (PUSER - 1),
+		msleep(&rms->owner, &rms->mtx, PRI_MAX_KERN,
 		    mtx_name(&rms->mtx), 0);
 		MPASS(rms->readers == 0);
 		KASSERT(rms->owner == RMS_TRANSIENT,
@@ -1213,7 +1214,7 @@
 	rms_assert_no_pcpu_readers(rms);
 
 	if (rms->readers > 0) {
-		msleep(&rms->writers, &rms->mtx, (PUSER - 1),
+		msleep(&rms->writers, &rms->mtx, PRI_MAX_KERN,
 		    mtx_name(&rms->mtx), 0);
 	}
 
diff --git a/sys/kern/subr_log.c b/sys/kern/subr_log.c
--- a/sys/kern/subr_log.c
+++ b/sys/kern/subr_log.c
@@ -47,7 +47,7 @@
 #include <sys/filedesc.h>
 #include <sys/sysctl.h>
 
-#define LOG_RDPRI	(PZERO + 1)
+#define LOG_RDPRI	PZERO
 
 #define LOG_ASYNC	0x04
 
diff --git a/sys/kern/sysv_msg.c b/sys/kern/sysv_msg.c
--- a/sys/kern/sysv_msg.c
+++ b/sys/kern/sysv_msg.c
@@ -894,7 +894,7 @@
 				we_own_it = 1;
 			}
 			DPRINTF(("msgsnd:  goodnight\n"));
-			error = msleep(msqkptr, &msq_mtx, (PZERO - 4) | PCATCH,
+			error = msleep(msqkptr, &msq_mtx, PVFS | PCATCH,
 			    "msgsnd", hz);
 			DPRINTF(("msgsnd:  good morning, error=%d\n", error));
 			if (we_own_it)
@@ -1303,7 +1303,7 @@
 		 */
 
 		DPRINTF(("msgrcv:  goodnight\n"));
-		error = msleep(msqkptr, &msq_mtx, (PZERO - 4) | PCATCH,
+		error = msleep(msqkptr, &msq_mtx, PVFS | PCATCH,
 		    "msgrcv", 0);
 		DPRINTF(("msgrcv:  good morning (error=%d)\n", error));
 
diff --git a/sys/kern/sysv_sem.c b/sys/kern/sysv_sem.c
--- a/sys/kern/sysv_sem.c
+++ b/sys/kern/sysv_sem.c
@@ -1309,7 +1309,7 @@
 			semptr->semncnt++;
 
 		DPRINTF(("semop:  good night!\n"));
-		error = msleep_sbt(semakptr, sema_mtxp, (PZERO - 4) | PCATCH,
+		error = msleep_sbt(semakptr, sema_mtxp, PVFS | PCATCH,
 		    "semwait", sbt, precision, C_ABSOLUTE);
 		DPRINTF(("semop:  good morning (error=%d)!\n", error));
 		/* return code is checked below, after sem[nz]cnt-- */
diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -756,7 +756,7 @@
 				break;
 		}
 		error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd),
-		    (PRIBIO + 4) | slpflag, "newbuf", slptimeo);
+		    PVFS | slpflag, "newbuf", slptimeo);
 		if (error != 0)
 			break;
 	}
@@ -2654,8 +2654,7 @@
 		mtx_lock(&bdirtylock);
 		while (buf_dirty_count_severe()) {
 			bdirtywait = 1;
-			msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
-			    "flswai", 0);
+			msleep(&bdirtywait, &bdirtylock, PVFS, "flswai", 0);
 		}
 		mtx_unlock(&bdirtylock);
 	}
@@ -5234,7 +5233,7 @@
 	while (bo->bo_numoutput) {
 		bo->bo_flag |= BO_WWAIT;
 		error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo),
-		    slpflag | (PRIBIO + 1), "bo_wwait", timeo);
+		    slpflag | PRIBIO, "bo_wwait", timeo);
 		if (error)
 			break;
 	}
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -787,7 +787,7 @@
 		}
 		DROP_GIANT();
 		sleepq_add(&fp->f_vnread_flags, NULL, "vofflock", 0, 0);
-		sleepq_wait(&fp->f_vnread_flags, PUSER -1);
+		sleepq_wait(&fp->f_vnread_flags, PRI_MAX_KERN);
 		PICKUP_GIANT();
 		sleepq_lock(&fp->f_vnread_flags);
 		state = atomic_load_16(flagsp);
@@ -849,7 +849,7 @@
 	if ((flags & FOF_NOLOCK) == 0) {
 		while (fp->f_vnread_flags & FOFFSET_LOCKED) {
 			fp->f_vnread_flags |= FOFFSET_LOCK_WAITING;
-			msleep(&fp->f_vnread_flags, mtxp, PUSER -1,
+			msleep(&fp->f_vnread_flags, mtxp, PRI_MAX_KERN,
 			    "vofflock", 0);
 		}
 		fp->f_vnread_flags |= FOFFSET_LOCKED;
@@ -1897,7 +1897,7 @@
 			if (flags & V_PCATCH)
 				mflags |= PCATCH;
 		}
-		mflags |= (PUSER - 1);
+		mflags |= PRI_MAX_KERN;
 		while ((mp->mnt_kern_flag & MNTK_SUSPEND) != 0) {
 			if ((flags & V_NOWAIT) != 0) {
 				error = EWOULDBLOCK;
@@ -2022,7 +2022,7 @@
 		if ((flags & V_PCATCH) != 0)
 			mflags |= PCATCH;
 	}
-	mflags |= (PUSER - 1) | PDROP;
+	mflags |= PRI_MAX_KERN | PDROP;
 	error = msleep(&mp->mnt_flag, MNT_MTX(mp), mflags, "suspfs", 0);
 	vfs_rel(mp);
 	if (error == 0)
@@ -2107,7 +2107,7 @@
 		return (EALREADY);
 	}
 	while (mp->mnt_kern_flag & MNTK_SUSPEND)
-		msleep(&mp->mnt_flag, MNT_MTX(mp), PUSER - 1, "wsuspfs", 0);
+		msleep(&mp->mnt_flag, MNT_MTX(mp), PRI_MAX_KERN, "wsuspfs", 0);
 
 	/*
 	 * Unmount holds a write reference on the mount point.  If we
@@ -2128,7 +2128,7 @@
 	mp->mnt_susp_owner = curthread;
 	if (mp->mnt_writeopcount > 0)
 		(void) msleep(&mp->mnt_writeopcount, 
-		    MNT_MTX(mp), (PUSER - 1)|PDROP, "suspwt", 0);
+		    MNT_MTX(mp), PRI_MAX_KERN | PDROP, "suspwt", 0);
 	else
 		MNT_IUNLOCK(mp);
 	if ((error = VFS_SYNC(mp, MNT_SUSPEND)) != 0) {
diff --git a/sys/net/if_tuntap.c b/sys/net/if_tuntap.c
--- a/sys/net/if_tuntap.c
+++ b/sys/net/if_tuntap.c
@@ -834,7 +834,7 @@
 		tp->tun_flags &= ~TUN_RWAIT;
 		wakeup(tp);
 	}
-	selwakeuppri(&tp->tun_rsel, PZERO + 1);
+	selwakeuppri(&tp->tun_rsel, PZERO);
 	KNOTE_LOCKED(&tp->tun_rsel.si_note, 0);
 	if (tp->tun_flags & TUN_ASYNC && tp->tun_sigio) {
 		TUN_UNLOCK(tp);
@@ -1169,7 +1169,7 @@
 	CURVNET_RESTORE();
 
 	funsetown(&tp->tun_sigio);
-	selwakeuppri(&tp->tun_rsel, PZERO + 1);
+	selwakeuppri(&tp->tun_rsel, PZERO);
 	KNOTE_LOCKED(&tp->tun_rsel.si_note, 0);
 	TUNDEBUG (ifp, "closed\n");
 	tp->tun_flags &= ~TUN_OPEN;
@@ -1703,7 +1703,7 @@
 			return (EWOULDBLOCK);
 		}
 		tp->tun_flags |= TUN_RWAIT;
-		error = mtx_sleep(tp, &tp->tun_mtx, PCATCH | (PZERO + 1),
+		error = mtx_sleep(tp, &tp->tun_mtx, PCATCH | PZERO,
 		    "tunread", 0);
 		if (error != 0) {
 			TUN_UNLOCK(tp);
diff --git a/sys/netgraph/ng_device.c b/sys/netgraph/ng_device.c
--- a/sys/netgraph/ng_device.c
+++ b/sys/netgraph/ng_device.c
@@ -462,7 +462,7 @@
 			mtx_lock(&priv->ngd_mtx);
 			priv->flags |= NGDF_RWAIT;
 			if ((error = msleep(priv, &priv->ngd_mtx,
-			    PDROP | PCATCH | (PZERO + 1),
+			    PDROP | PCATCH | PZERO,
 			    "ngdread", 0)) != 0)
 				return (error);
 		}
diff --git a/sys/sys/buf.h b/sys/sys/buf.h
--- a/sys/sys/buf.h
+++ b/sys/sys/buf.h
@@ -296,7 +296,7 @@
  * Initialize a lock.
  */
 #define BUF_LOCKINIT(bp, wmesg)						\
-	lockinit(&(bp)->b_lock, PRIBIO + 4, wmesg, 0, LK_NEW)
+	lockinit(&(bp)->b_lock, PVFS, wmesg, 0, LK_NEW)
 /*
  *
  * Get a lock sleeping non-interruptably until it becomes available.
@@ -311,7 +311,7 @@
  */
 #define	BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo)	\
 	_lockmgr_args_rw(&(bp)->b_lock, (locktype) | LK_TIMELOCK,	\
-	    (interlock), (wmesg), (PRIBIO + 4) | (catch), (timo),	\
+	    (interlock), (wmesg), PVFS | (catch), (timo),	\
 	    LOCK_FILE, LOCK_LINE)
 
 /*
diff --git a/sys/sys/param.h b/sys/sys/param.h
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -73,7 +73,7 @@
  * cannot include sys/param.h and should only be updated here.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1500023
+#define __FreeBSD_version 1500024
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
diff --git a/sys/sys/runq.h b/sys/sys/runq.h
--- a/sys/sys/runq.h
+++ b/sys/sys/runq.h
@@ -29,12 +29,20 @@
 #ifndef	_RUNQ_H_
 #define	_RUNQ_H_
 
+#ifndef _KERNEL
+#error "no user-serviceable parts inside"
+#endif
+
+#include <sys/types.h>		/* For bool. */
+
+struct thread;
+
 /*
  * Run queue parameters.
  */
 
 #define	RQ_MAX_PRIO	(255)	/* Maximum priority (minimum is 0). */
-#define	RQ_PPQ		(4)	/* Priorities per queue. */
+#define	RQ_PPQ		(1)	/* Priorities per queue. */
 
 /*
  * Convenience macros from <sys/param.h>.
@@ -71,11 +79,6 @@
 	RQSW_TO_QUEUE_IDX(word_idx, RQSW_BSF(word))
 
 
-#ifdef _KERNEL
-#include <sys/types.h>		/* For bool. */
-
-struct thread;
-
 /*
  * The queue for a given index as a list of threads.
  */
@@ -118,6 +121,5 @@
 bool		 runq_not_empty(struct runq *);
 struct thread	*runq_choose(struct runq *);
 struct thread	*runq_choose_fuzz(struct runq *, int _fuzz);
-#endif /* _KERNEL */
 
 #endif
diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c
--- a/sys/ufs/ffs/ffs_softdep.c
+++ b/sys/ufs/ffs/ffs_softdep.c
@@ -497,7 +497,7 @@
 	while (mp->mnt_secondary_writes != 0) {
 		BO_UNLOCK(bo);
 		msleep(&mp->mnt_secondary_writes, MNT_MTX(mp),
-		    (PUSER - 1) | PDROP, "secwr", 0);
+		    PRI_MAX_KERN | PDROP, "secwr", 0);
 		BO_LOCK(bo);
 		MNT_ILOCK(mp);
 	}
@@ -14557,7 +14557,7 @@
 		while (mp->mnt_secondary_writes != 0) {
 			BO_UNLOCK(bo);
 			msleep(&mp->mnt_secondary_writes, MNT_MTX(mp),
-			    (PUSER - 1) | PDROP, "secwr", 0);
+			    PRI_MAX_KERN | PDROP, "secwr", 0);
 			BO_LOCK(bo);
 			MNT_ILOCK(mp);
 		}
@@ -14597,7 +14597,7 @@
 			BO_UNLOCK(bo);
 			msleep(&mp->mnt_secondary_writes,
 			       MNT_MTX(mp),
-			       (PUSER - 1) | PDROP, "secwr", 0);
+			       PRI_MAX_KERN | PDROP, "secwr", 0);
 			BO_LOCK(bo);
 			continue;
 		}
diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c
--- a/sys/ufs/ffs/ffs_vnops.c
+++ b/sys/ufs/ffs/ffs_vnops.c
@@ -1399,8 +1399,7 @@
 	VI_LOCK(vp);
 	while (ip->i_flag & IN_EA_LOCKED) {
 		UFS_INODE_SET_FLAG(ip, IN_EA_LOCKWAIT);
-		msleep(&ip->i_ea_refs, &vp->v_interlock, PINOD + 2, "ufs_ea",
-		    0);
+		msleep(&ip->i_ea_refs, &vp->v_interlock, PINOD, "ufs_ea", 0);
 	}
 	UFS_INODE_SET_FLAG(ip, IN_EA_LOCKED);
 	VI_UNLOCK(vp);
diff --git a/sys/ufs/ufs/ufs_quota.c b/sys/ufs/ufs/ufs_quota.c
--- a/sys/ufs/ufs/ufs_quota.c
+++ b/sys/ufs/ufs/ufs_quota.c
@@ -179,7 +179,7 @@
 			if ((dq = ip->i_dquot[i]) == NODQUOT)
 				continue;
 			DQI_LOCK(dq);
-			DQI_WAIT(dq, PINOD+1, "chkdq1");
+			DQI_WAIT(dq, PINOD, "chkdq1");
 			ncurblocks = dq->dq_curblocks + change;
 			if (ncurblocks >= 0)
 				dq->dq_curblocks = ncurblocks;
@@ -201,7 +201,7 @@
 			continue;
 		warn = 0;
 		DQI_LOCK(dq);
-		DQI_WAIT(dq, PINOD+1, "chkdq2");
+		DQI_WAIT(dq, PINOD, "chkdq2");
 		if (do_check) {
 			error = chkdqchg(ip, change, cred, i, &warn);
 			if (error) {
@@ -215,7 +215,7 @@
 					if (dq == NODQUOT)
 						continue;
 					DQI_LOCK(dq);
-					DQI_WAIT(dq, PINOD+1, "chkdq3");
+					DQI_WAIT(dq, PINOD, "chkdq3");
 					ncurblocks = dq->dq_curblocks - change;
 					if (ncurblocks >= 0)
 						dq->dq_curblocks = ncurblocks;
@@ -320,7 +320,7 @@
 			if ((dq = ip->i_dquot[i]) == NODQUOT)
 				continue;
 			DQI_LOCK(dq);
-			DQI_WAIT(dq, PINOD+1, "chkiq1");
+			DQI_WAIT(dq, PINOD, "chkiq1");
 			if (dq->dq_curinodes >= -change)
 				dq->dq_curinodes += change;
 			else
@@ -341,7 +341,7 @@
 			continue;
 		warn = 0;
 		DQI_LOCK(dq);
-		DQI_WAIT(dq, PINOD+1, "chkiq2");
+		DQI_WAIT(dq, PINOD, "chkiq2");
 		if (do_check) {
 			error = chkiqchg(ip, change, cred, i, &warn);
 			if (error) {
@@ -355,7 +355,7 @@
 					if (dq == NODQUOT)
 						continue;
 					DQI_LOCK(dq);
-					DQI_WAIT(dq, PINOD+1, "chkiq3");
+					DQI_WAIT(dq, PINOD, "chkiq3");
 					if (dq->dq_curinodes >= change)
 						dq->dq_curinodes -= change;
 					else
@@ -855,7 +855,7 @@
 		return (error);
 	dq = ndq;
 	DQI_LOCK(dq);
-	DQI_WAIT(dq, PINOD+1, "setqta");
+	DQI_WAIT(dq, PINOD, "setqta");
 	/*
 	 * Copy all but the current values.
 	 * Reset time limit if previously had no soft limit or were
@@ -918,7 +918,7 @@
 		return (error);
 	dq = ndq;
 	DQI_LOCK(dq);
-	DQI_WAIT(dq, PINOD+1, "setuse");
+	DQI_WAIT(dq, PINOD, "setuse");
 	/*
 	 * Reset time limit if have a soft limit and were
 	 * previously under it, but are now over it.
@@ -1314,7 +1314,7 @@
 	if (dq != NULL) {
 		DQH_UNLOCK();
 hfound:		DQI_LOCK(dq);
-		DQI_WAIT(dq, PINOD+1, "dqget");
+		DQI_WAIT(dq, PINOD, "dqget");
 		DQI_UNLOCK(dq);
 		if (dq->dq_ump == NULL) {
 			dqrele(vp, dq);
@@ -1588,7 +1588,7 @@
 		vn_lock(dqvp, LK_EXCLUSIVE | LK_RETRY);
 
 	DQI_LOCK(dq);
-	DQI_WAIT(dq, PINOD+2, "dqsync");
+	DQI_WAIT(dq, PINOD, "dqsync");
 	if ((dq->dq_flags & DQ_MOD) == 0)
 		goto out;
 	dq->dq_flags |= DQ_LOCK;
@@ -1742,7 +1742,7 @@
 		if ((dq = qrp[i]) == NODQUOT)
 			continue;
 		DQI_LOCK(dq);
-		DQI_WAIT(dq, PINOD+1, "adjqta");
+		DQI_WAIT(dq, PINOD, "adjqta");
 		ncurblocks = dq->dq_curblocks + blkcount;
 		if (ncurblocks >= 0)
 			dq->dq_curblocks = ncurblocks;
diff --git a/tests/sys/kern/ptrace_test.c b/tests/sys/kern/ptrace_test.c
--- a/tests/sys/kern/ptrace_test.c
+++ b/tests/sys/kern/ptrace_test.c
@@ -34,7 +34,6 @@
 #include <sys/ptrace.h>
 #include <sys/procfs.h>
 #include <sys/queue.h>
-#include <sys/runq.h>
 #include <sys/syscall.h>
 #include <sys/sysctl.h>
 #include <sys/user.h>
@@ -2027,7 +2026,7 @@
 		    sched_get_priority_min(SCHED_FIFO)) / 2;
 		CHILD_REQUIRE(pthread_setschedparam(pthread_self(),
 		    SCHED_FIFO, &sched_param) == 0);
-		sched_param.sched_priority -= RQ_PPQ;
+		sched_param.sched_priority -= 1;
 		CHILD_REQUIRE(pthread_setschedparam(t, SCHED_FIFO,
 		    &sched_param) == 0);
 
@@ -2130,7 +2129,7 @@
 		    sched_get_priority_min(SCHED_FIFO)) / 2;
 		CHILD_REQUIRE(pthread_setschedparam(pthread_self(),
 		    SCHED_FIFO, &sched_param) == 0);
-		sched_param.sched_priority -= RQ_PPQ;
+		sched_param.sched_priority -= 1;
 		CHILD_REQUIRE(pthread_setschedparam(t, SCHED_FIFO,
 		    &sched_param) == 0);