PSARC 2008/138 Soft CPU and processor set bindings

6656791 Weaker CPU and processor set bindings is useful

12 files changed, 217 insertions, 54 deletions

diff --git a/usr/src/uts/common/disp/cpupart.c b/usr/src/uts/common/disp/cpupart.c
index ecd5aff873..715813600e 100644
--- a/usr/src/uts/common/disp/cpupart.c
+++ b/usr/src/uts/common/disp/cpupart.c
@@ -19,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -100,6 +100,9 @@ static uint_t		cp_max_numparts;
 #define	PSTOCP(psid)	((cpupartid_t)((psid) == PS_NONE ? CP_DEFAULT : (psid)))
 #define	CPTOPS(cpid)	((psetid_t)((cpid) == CP_DEFAULT ? PS_NONE : (cpid)))
 
+
+static int cpupart_unbind_threads(cpupart_t *, boolean_t);
+
 /*
  * Find a CPU partition given a processor set ID.
  */
@@ -284,6 +287,7 @@ cpupart_move_cpu(cpu_t *cp, cpupart_t *newpp, int forced)
 	int lgrp_diff_lpl;
 	lpl_t	*cpu_lpl;
 	int	ret;
+	boolean_t unbind_all_threads = (forced != 0);
 
 	ASSERT(MUTEX_HELD(&cpu_lock));
 	ASSERT(newpp != NULL);
@@ -309,11 +313,38 @@ cpupart_move_cpu(cpu_t *cp, cpupart_t *newpp, int forced)
 		 */
 		move_threads = 0;
 	} else if (oldpp->cp_ncpus == 1) {
-		cpu_state_change_notify(cp->cpu_id, CPU_CPUPART_IN);
-		return (EBUSY);
+		/*
+		 * The last CPU is removed from a partition which has threads
+		 * running in it. Some of these threads may be bound to this
+		 * CPU.
+		 *
+		 * Attempt to unbind threads from the CPU and from the processor
+		 * set. Note that no threads should be bound to this CPU since
+		 * cpupart_move_threads will refuse to move bound threads to
+		 * other CPUs.
+		 */
+		(void) cpu_unbind(oldpp->cp_cpulist->cpu_id, B_FALSE);
+		(void) cpupart_unbind_threads(oldpp, B_FALSE);
+
+		if (!disp_bound_partition(cp, 0)) {
+			/*
+			 * No bound threads in this partition any more
+			 */
+			move_threads = 0;
+		} else {
+			/*
+			 * There are still threads bound to the partition
+			 */
+			cpu_state_change_notify(cp->cpu_id, CPU_CPUPART_IN);
+			return (EBUSY);
+		}
 	}
 
-	if (forced && (ret = cpu_unbind(cp->cpu_id)) != 0) {
+	/*
+	 * If forced flag is set unbind any threads from this CPU.
+	 * Otherwise unbind soft-bound threads only.
+	 */
+	if ((ret = cpu_unbind(cp->cpu_id, unbind_all_threads)) != 0) {
 		cpu_state_change_notify(cp->cpu_id, CPU_CPUPART_IN);
 		return (ret);
 	}
@@ -798,26 +829,23 @@ cpupart_create(psetid_t *psid)
 	return (0);
 }
 
-
 /*
- * Destroy a partition.
+ * Move threads from specified partition to cp_default. If `force' is specified,
+ * move all threads, otherwise move only soft-bound threads.
  */
-int
-cpupart_destroy(psetid_t psid)
+static int
+cpupart_unbind_threads(cpupart_t *pp, boolean_t unbind_all)
 {
-	cpu_t	*cp, *first_cp;
-	cpupart_t *pp, *newpp;
-	int	err = 0;
 	void 	*projbuf, *zonebuf;
 	kthread_t *t;
 	proc_t	*p;
+	int	err = 0;
+	psetid_t psid = pp->cp_id;
 
 	ASSERT(pool_lock_held());
-	mutex_enter(&cpu_lock);
+	ASSERT(MUTEX_HELD(&cpu_lock));
 
-	pp = cpupart_find(psid);
 	if (pp == NULL || pp == &cp_default) {
-		mutex_exit(&cpu_lock);
 		return (EINVAL);
 	}
 
@@ -829,10 +857,6 @@ cpupart_destroy(psetid_t psid)
 	projbuf = fss_allocbuf(FSS_NPROJ_BUF, FSS_ALLOC_PROJ);
 	zonebuf = fss_allocbuf(FSS_NPROJ_BUF, FSS_ALLOC_ZONE);
 
-	/*
-	 * First need to unbind all the threads currently bound to the
-	 * partition.  Then do the actual destroy (which moves the CPUs).
-	 */
 	mutex_enter(&pidlock);
 	t = curthread;
 	do {
@@ -847,17 +871,23 @@ again:			p = ttoproc(t);
 				mutex_exit(&p->p_lock);
 				goto again;
 			}
-			err = cpupart_bind_thread(t, PS_NONE, 1,
-			    projbuf, zonebuf);
-			if (err) {
-				mutex_exit(&p->p_lock);
-				mutex_exit(&pidlock);
-				mutex_exit(&cpu_lock);
-				fss_freebuf(projbuf, FSS_ALLOC_PROJ);
-				fss_freebuf(zonebuf, FSS_ALLOC_ZONE);
-				return (err);
+
+			/*
+			 * Can only unbind threads which have revocable binding
+			 * unless force unbinding requested.
+			 */
+			if (unbind_all || TB_PSET_IS_SOFT(t)) {
+				err = cpupart_bind_thread(t, PS_NONE, 1,
+				    projbuf, zonebuf);
+				if (err) {
+					mutex_exit(&p->p_lock);
+					mutex_exit(&pidlock);
+					fss_freebuf(projbuf, FSS_ALLOC_PROJ);
+					fss_freebuf(zonebuf, FSS_ALLOC_ZONE);
+					return (err);
+				}
+				t->t_bind_pset = PS_NONE;
 			}
-			t->t_bind_pset = PS_NONE;
 			mutex_exit(&p->p_lock);
 		}
 		t = t->t_next;
@@ -866,6 +896,36 @@ again:			p = ttoproc(t);
 	mutex_exit(&pidlock);
 	fss_freebuf(projbuf, FSS_ALLOC_PROJ);
 	fss_freebuf(zonebuf, FSS_ALLOC_ZONE);
+	return (err);
+}
+
+/*
+ * Destroy a partition.
+ */
+int
+cpupart_destroy(psetid_t psid)
+{
+	cpu_t	*cp, *first_cp;
+	cpupart_t *pp, *newpp;
+	int	err = 0;
+
+	ASSERT(pool_lock_held());
+	mutex_enter(&cpu_lock);
+
+	pp = cpupart_find(psid);
+	if (pp == NULL || pp == &cp_default) {
+		mutex_exit(&cpu_lock);
+		return (EINVAL);
+	}
+
+	/*
+	 * Unbind all the threads currently bound to the partition.
+	 */
+	err = cpupart_unbind_threads(pp, B_TRUE);
+	if (err) {
+		mutex_exit(&cpu_lock);
+		return (err);
+	}
 
 	newpp = &cp_default;
 	while ((cp = pp->cp_cpulist) != NULL) {
diff --git a/usr/src/uts/common/disp/thread.c b/usr/src/uts/common/disp/thread.c
index 27e6034f05..0d4fd8e26c 100644
--- a/usr/src/uts/common/disp/thread.c
+++ b/usr/src/uts/common/disp/thread.c
@@ -107,6 +107,9 @@ int lwp_cache_sz = 32;
 int t_cache_sz = 8;
 static kt_did_t next_t_id = 1;
 
+/* Default mode for thread binding to CPUs and processor sets */
+int default_binding_mode = TB_ALLHARD;
+
 /*
  * Min/Max stack sizes for stack size parameters
  */
@@ -419,6 +422,7 @@ thread_create(
 	t->t_stime = lbolt;
 	t->t_schedflag = TS_LOAD | TS_DONT_SWAP;
 	t->t_bind_cpu = PBIND_NONE;
+	t->t_bindflag = (uchar_t)default_binding_mode;
 	t->t_bind_pset = PS_NONE;
 	t->t_plockp = &pp->p_lock;
 	t->t_copyops = NULL;
diff --git a/usr/src/uts/common/os/cpu.c b/usr/src/uts/common/os/cpu.c
index 80c2198c80..a06b5fb189 100644
--- a/usr/src/uts/common/os/cpu.c
+++ b/usr/src/uts/common/os/cpu.c
@@ -1231,6 +1231,7 @@ cpu_offline(cpu_t *cp, int flags)
 	lpl_t	*cpu_lpl;
 	proc_t	*p;
 	int	lgrp_diff_lpl;
+	boolean_t unbind_all_threads = (flags & CPU_FORCED) != 0;
 
 	ASSERT(MUTEX_HELD(&cpu_lock));
 
@@ -1258,9 +1259,11 @@ cpu_offline(cpu_t *cp, int flags)
 	if (ncpus_online <= 1 || pp->cp_ncpus <= 1 || cpu_intr_count(cp) < 2)
 		return (EBUSY);
 	/*
-	 * Unbind all thread bound to our CPU if we were asked to.
+	 * Unbind all soft-bound threads bound to our CPU and hard bound threads
+	 * if we were asked to.
 	 */
-	if (flags & CPU_FORCED && (error = cpu_unbind(cp->cpu_id)) != 0)
+	error = cpu_unbind(cp->cpu_id, unbind_all_threads);
+	if (error != 0)
 		return (error);
 	/*
 	 * We shouldn't be bound to this CPU ourselves.
@@ -2434,7 +2437,7 @@ cpu_bind_thread(kthread_id_t tp, processorid_t bind, processorid_t *obind,
     int *error)
 {
 	processorid_t	binding;
-	cpu_t		*cp;
+	cpu_t		*cp = NULL;
 
 	ASSERT(MUTEX_HELD(&cpu_lock));
 	ASSERT(MUTEX_HELD(&ttoproc(tp)->p_lock));
@@ -2447,12 +2450,47 @@ cpu_bind_thread(kthread_id_t tp, processorid_t bind, processorid_t *obind,
 	 * reporting PBIND_NONE for a process when some LWPs are bound.
 	 */
 	binding = tp->t_bind_cpu;
-	if (binding != PBIND_NONE)
-		*obind = binding;	/* record old binding */
 
-	if (bind == PBIND_QUERY) {
+	switch (bind) {
+	case PBIND_QUERY:
+		/* Just return the old binding */
+		*obind = binding;
+		thread_unlock(tp);
+		return (0);
+
+	case PBIND_QUERY_TYPE:
+		/* Return the binding type */
+		*obind = TB_CPU_IS_SOFT(tp) ? PBIND_SOFT : PBIND_HARD;
+		thread_unlock(tp);
+		return (0);
+
+	case PBIND_SOFT:
+		/*
+		 *  Set soft binding for this thread and return the actual
+		 *  binding
+		 */
+		TB_CPU_SOFT_SET(tp);
+		*obind = binding;
+		thread_unlock(tp);
+		return (0);
+
+	case PBIND_HARD:
+		/*
+		 *  Set hard binding for this thread and return the actual
+		 *  binding
+		 */
+		TB_CPU_HARD_SET(tp);
+		*obind = binding;
 		thread_unlock(tp);
 		return (0);
+
+	case PBIND_NONE:
+		break;
+
+	default:
+		/* record old binding */
+		*obind = binding;
+		break;
 	}
 
 	/*
@@ -2472,11 +2510,11 @@ cpu_bind_thread(kthread_id_t tp, processorid_t bind, processorid_t *obind,
 
 	binding = bind;
 	if (binding != PBIND_NONE) {
-		cp = cpu[binding];
+		cp = cpu_get((processorid_t)binding);
 		/*
-		 * Make sure binding is in right partition.
+		 * Make sure binding is valid and is in right partition.
 		 */
-		if (tp->t_cpupart != cp->cpu_part) {
+		if (cp == NULL || tp->t_cpupart != cp->cpu_part) {
 			*error = EINVAL;
 			thread_unlock(tp);
 			return (0);
@@ -2702,10 +2740,13 @@ cpuset_bounds(cpuset_t *s, uint_t *smallestid, uint_t *largestid)
 #endif	/* CPUSET_WORDS */
 
 /*
- * Unbind all user threads bound to a given CPU.
+ * Unbind threads bound to specified CPU.
+ *
+ * If `unbind_all_threads' is true, unbind all user threads bound to a given
+ * CPU. Otherwise unbind all soft-bound user threads.
  */
 int
-cpu_unbind(processorid_t cpu)
+cpu_unbind(processorid_t cpu, boolean_t unbind_all_threads)
 {
 	processorid_t obind;
 	kthread_t *tp;
@@ -2731,6 +2772,12 @@ cpu_unbind(processorid_t cpu)
 		do {
 			if (tp->t_bind_cpu != cpu)
 				continue;
+			/*
+			 * Skip threads with hard binding when
+			 * `unbind_all_threads' is not specified.
+			 */
+			if (!unbind_all_threads && TB_CPU_IS_HARD(tp))
+				continue;
 			err = cpu_bind_thread(tp, PBIND_NONE, &obind, &berr);
 			if (ret == 0)
 				ret = err;
diff --git a/usr/src/uts/common/os/lwp.c b/usr/src/uts/common/os/lwp.c
index 39ca56ac7d..d80f32c658 100644
--- a/usr/src/uts/common/os/lwp.c
+++ b/usr/src/uts/common/os/lwp.c
@@ -346,12 +346,15 @@ grow:
 		t->t_bind_cpu = binding = PBIND_NONE;
 		t->t_cpupart = oldpart = &cp_default;
 		t->t_bind_pset = PS_NONE;
+		t->t_bindflag = (uchar_t)default_binding_mode;
 	} else {
 		binding = curthread->t_bind_cpu;
 		t->t_bind_cpu = binding;
 		oldpart = t->t_cpupart;
 		t->t_cpupart = curthread->t_cpupart;
 		t->t_bind_pset = curthread->t_bind_pset;
+		t->t_bindflag = curthread->t_bindflag |
+		    (uchar_t)default_binding_mode;
 	}
 
 	/*
diff --git a/usr/src/uts/common/sys/cpuvar.h b/usr/src/uts/common/sys/cpuvar.h
index c7b76b32ea..cd0d027866 100644
--- a/usr/src/uts/common/sys/cpuvar.h
+++ b/usr/src/uts/common/sys/cpuvar.h
@@ -668,7 +668,7 @@ void	cpu_destroy_bound_threads(cpu_t *cp);
 
 extern int cpu_bind_thread(kthread_t *tp, processorid_t bind,
     processorid_t *obind, int *error);
-extern int cpu_unbind(processorid_t cpu_id);
+extern int cpu_unbind(processorid_t cpu_id, boolean_t force);
 extern void thread_affinity_set(kthread_t *t, int cpu_id);
 extern void thread_affinity_clear(kthread_t *t);
 extern void affinity_set(int cpu_id);
diff --git a/usr/src/uts/common/sys/processor.h b/usr/src/uts/common/sys/processor.h
index 4d6f90e988..3a76c8c9b4 100644
--- a/usr/src/uts/common/sys/processor.h
+++ b/usr/src/uts/common/sys/processor.h
@@ -25,7 +25,7 @@
  */
 
 /*
- * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -106,6 +106,9 @@ typedef struct {
  */
 #define	PBIND_NONE	-1	/* LWP/thread is not bound */
 #define	PBIND_QUERY	-2	/* don't set, just return the binding */
+#define	PBIND_HARD	-3	/* prevents offlining CPU (default) */
+#define	PBIND_SOFT	-4	/* allows offlining CPU */
+#define	PBIND_QUERY_TYPE	-5	/* Return binding type */
 
 /*
  * User-level system call interface prototypes
diff --git a/usr/src/uts/common/sys/pset.h b/usr/src/uts/common/sys/pset.h
index 395b3850a8..f98e327620 100644
--- a/usr/src/uts/common/sys/pset.h
+++ b/usr/src/uts/common/sys/pset.h
@@ -2,9 +2,8 @@
  * CDDL HEADER START
  *
  * The contents of this file are subject to the terms of the
- * Common Development and Distribution License, Version 1.0 only
- * (the "License").  You may not use this file except in compliance
- * with the License.
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
  *
  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  * or http://www.opensolaris.org/os/licensing.
@@ -20,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -45,6 +44,9 @@ typedef int psetid_t;
 #define	PS_NONE		-1
 #define	PS_QUERY	-2
 #define	PS_MYID		-3
+#define	PS_SOFT		-4
+#define	PS_HARD		-5
+#define	PS_QUERY_TYPE	-6
 
 /* types of processor sets */
 #define	PS_SYSTEM	1
diff --git a/usr/src/uts/common/sys/thread.h b/usr/src/uts/common/sys/thread.h
index 6fced086b3..eee18d53f9 100644
--- a/usr/src/uts/common/sys/thread.h
+++ b/usr/src/uts/common/sys/thread.h
@@ -125,6 +125,7 @@ typedef struct _kthread {
 	pri_t	t_epri;		/* inherited thread priority */
 	pri_t	t_cpri;		/* thread scheduling class priority */
 	char	t_writer;	/* sleeping in lwp_rwlock_lock(RW_WRITE_LOCK) */
+	uchar_t	t_bindflag;	/* CPU and pset binding type */
 	label_t	t_pcb;		/* pcb, save area when switching */
 	lwpchan_t t_lwpchan;	/* reason for blocking */
 #define	t_wchan0	t_lwpchan.lc_wchan0
@@ -415,6 +416,21 @@ typedef struct _kthread {
 #define	TS_ANYWAITQ	(TS_PROJWAITQ|TS_ZONEWAITQ)
 
 /*
+ * Thread binding types
+ */
+#define	TB_ALLHARD	0
+#define	TB_CPU_SOFT	0x01		/* soft binding to CPU */
+#define	TB_PSET_SOFT	0x02		/* soft binding to pset */
+
+#define	TB_CPU_SOFT_SET(t)		((t)->t_bindflag |= TB_CPU_SOFT)
+#define	TB_CPU_HARD_SET(t)		((t)->t_bindflag &= ~TB_CPU_SOFT)
+#define	TB_PSET_SOFT_SET(t)		((t)->t_bindflag |= TB_PSET_SOFT)
+#define	TB_PSET_HARD_SET(t)		((t)->t_bindflag &= ~TB_PSET_SOFT)
+#define	TB_CPU_IS_SOFT(t)		((t)->t_bindflag & TB_CPU_SOFT)
+#define	TB_CPU_IS_HARD(t)		(!TB_CPU_IS_SOFT(t))
+#define	TB_PSET_IS_SOFT(t)		((t)->t_bindflag & TB_PSET_SOFT)
+
+/*
  * No locking needed for AST field.
  */
 #define	aston(t)		((t)->t_astflag = 1)
@@ -564,6 +580,8 @@ extern disp_lock_t stop_lock;		/* lock protecting stopped threads */
 
 caddr_t	thread_stk_init(caddr_t);	/* init thread stack */
 
+extern int default_binding_mode;
+
 #endif	/* _KERNEL */
 
 /*
diff --git a/usr/src/uts/common/syscall/processor_bind.c b/usr/src/uts/common/syscall/processor_bind.c
index 129129d7d1..7ff855a86b 100644
--- a/usr/src/uts/common/syscall/processor_bind.c
+++ b/usr/src/uts/common/syscall/processor_bind.c
@@ -19,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -219,6 +219,9 @@ processor_bind(idtype_t idtype, id_t id, processorid_t bind,
 
 	case PBIND_NONE:
 	case PBIND_QUERY:
+	case PBIND_HARD:
+	case PBIND_SOFT:
+	case PBIND_QUERY_TYPE:
 		break;
 	}
 
@@ -333,7 +336,7 @@ processor_bind(idtype_t idtype, id_t id, processorid_t bind,
 		if (id == P_MYID || bind != PBIND_NONE || cpu_get(id) == NULL)
 			ret = EINVAL;
 		else
-			ret = cpu_unbind(id);
+			ret = cpu_unbind(id, B_TRUE);
 		break;
 
 	case P_ALL:
@@ -345,7 +348,7 @@ processor_bind(idtype_t idtype, id_t id, processorid_t bind,
 			do {
 				if ((cp->cpu_flags & CPU_EXISTS) == 0)
 					continue;
-				i = cpu_unbind(cp->cpu_id);
+				i = cpu_unbind(cp->cpu_id, B_TRUE);
 				if (ret == 0)
 					ret = i;
 			} while ((cp = cp->cpu_next) != cpu_list);
diff --git a/usr/src/uts/common/syscall/pset.c b/usr/src/uts/common/syscall/pset.c
index 767529fc5d..b0427e009e 100644
--- a/usr/src/uts/common/syscall/pset.c
+++ b/usr/src/uts/common/syscall/pset.c
@@ -19,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -251,7 +251,24 @@ pset_bind_thread(kthread_t *tp, psetid_t pset, psetid_t *oldpset, void *projbuf,
 	ASSERT(MUTEX_HELD(&ttoproc(tp)->p_lock));
 
 	*oldpset = tp->t_bind_pset;
-	if (pset != PS_QUERY) {
+
+	switch (pset) {
+	case PS_SOFT:
+		TB_PSET_SOFT_SET(tp);
+		break;
+
+	case PS_HARD:
+		TB_PSET_HARD_SET(tp);
+		break;
+
+	case PS_QUERY:
+		break;
+
+	case PS_QUERY_TYPE:
+		*oldpset = TB_PSET_IS_SOFT(tp) ? PS_SOFT : PS_HARD;
+		break;
+
+	default:
 		/*
 		 * Must have the same UID as the target process or
 		 * have PRIV_PROC_OWNER privilege.
@@ -273,7 +290,10 @@ pset_bind_thread(kthread_t *tp, psetid_t pset, psetid_t *oldpset, void *projbuf,
 		if ((error = cpupart_bind_thread(tp, pset, 0,
 		    projbuf, zonebuf)) == 0)
 			tp->t_bind_pset = pset;
+
+		break;
 	}
+
 	return (error);
 }
 
@@ -285,7 +305,7 @@ pset_bind_process(proc_t *pp, psetid_t pset, psetid_t *oldpset, void *projbuf,
 	kthread_t *tp;
 
 	/* skip kernel processes */
-	if (pset != PS_QUERY && pp->p_flag & SSYS) {
+	if ((pset != PS_QUERY) && pp->p_flag & SSYS) {
 		*oldpset = PS_NONE;
 		return (0);
 	}
@@ -463,7 +483,8 @@ pset_bind(psetid_t pset, idtype_t idtype, id_t id, psetid_t *opset)
 	void		*projbuf, *zonebuf;
 
 	pool_lock();
-	if (pset != PS_QUERY) {
+	if ((pset != PS_QUERY) && (pset != PS_SOFT) &&
+	    (pset != PS_HARD) && (pset != PS_QUERY_TYPE)) {
 		/*
 		 * Check if the set actually exists before checking
 		 * permissions.  This is the historical error
diff --git a/usr/src/uts/i86pc/os/mlsetup.c b/usr/src/uts/i86pc/os/mlsetup.c
index f33f60e320..c099fc9764 100644
--- a/usr/src/uts/i86pc/os/mlsetup.c
+++ b/usr/src/uts/i86pc/os/mlsetup.c
@@ -19,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -241,6 +241,7 @@ mlsetup(struct regs *rp)
 	t0.t_disp_queue = &cpu0_disp;
 	t0.t_bind_cpu = PBIND_NONE;
 	t0.t_bind_pset = PS_NONE;
+	t0.t_bindflag = (uchar_t)default_binding_mode;
 	t0.t_cpupart = &cp_default;
 	t0.t_clfuncs = &sys_classfuncs.thread;
 	t0.t_copyops = NULL;
diff --git a/usr/src/uts/sun4/os/mlsetup.c b/usr/src/uts/sun4/os/mlsetup.c
index 6cefe6cc99..db8066c8ca 100644
--- a/usr/src/uts/sun4/os/mlsetup.c
+++ b/usr/src/uts/sun4/os/mlsetup.c
@@ -19,7 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 
@@ -162,6 +162,7 @@ mlsetup(struct regs *rp, kfpu_t *fp)
 	t0.t_disp_queue = &cpu0_disp;
 	t0.t_bind_cpu = PBIND_NONE;
 	t0.t_bind_pset = PS_NONE;
+	t0.t_bindflag = (uchar_t)default_binding_mode;
 	t0.t_cpupart = &cp_default;
 	t0.t_clfuncs = &sys_classfuncs.thread;
 	t0.t_copyops = NULL;