After one of my analysis passes to evaluate methods for SMP TLB mgmt, I

noticed some major enhancements available for UP situations.  The number
of UP TLB flushes is decreased much more than significantly with these
changes.  Since a TLB flush appears to cost minimally approx 80 cycles,
this is a "nice" enhancement, equiv to eliminating between 40 and 160
instructions per TLB flush.

Changes include making sure that kernel threads all use the same PTD,
and eliminate unneeded PTD switches at context switch time.

14 files changed, 241 insertions, 42 deletions

diff --git a/sys/amd64/amd64/cpu_switch.S b/sys/amd64/amd64/cpu_switch.S
index 4d57b64..df0bda8 100644
--- a/sys/amd64/amd64/cpu_switch.S
+++ b/sys/amd64/amd64/cpu_switch.S
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.63 1997/09/21 15:03:58 peter Exp $
+ *	$Id: swtch.s,v 1.64 1997/10/10 09:44:06 peter Exp $
  */
 
 #include "npx.h"
@@ -86,6 +86,11 @@ _hlt_vector:	.long	_default_halt	/* pointer to halt routine */
 
 	.globl	_want_resched
 _want_resched:	.long	0		/* we need to re-run the scheduler */
+#if defined(SWTCH_OPTIM_STATS)
+	.globl	_swtch_optim_stats, _tlb_flush_count
+_swtch_optim_stats:	.long	0		/* number of _swtch_optims */
+_tlb_flush_count:	.long	0
+#endif
 
 	.text
 /*
@@ -252,6 +257,9 @@ _idle:
 	/* use our idleproc's "context" */
 	movl	_my_idlePTD,%ecx
 	movl	%ecx,%cr3
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	$_idlestack_top,%ecx
 	movl	%ecx,%esp
 
@@ -259,8 +267,7 @@ _idle:
 #ifdef VM86
 	movl	_my_tr, %esi
 #endif /* VM86 */
-	movl	$_common_tss, %eax
-	movl	%ecx, TSS_ESP0(%eax)
+	movl	%ecx, _common_tss + TSS_ESP0
 
 #ifdef VM86
 	btrl	%esi, _private_tss
@@ -302,6 +309,9 @@ _idle:
 	.globl	idle_loop
 idle_loop:
 
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	%cr3,%eax			/* ouch! */
 	movl	%eax,%cr3
 
@@ -357,15 +367,27 @@ idle_loop:
 #else
 	xorl	%ebp,%ebp
 	movl	$HIDENAME(tmpstk),%esp
-	movl	_IdlePTD,%ecx
-	movl	%ecx,%cr3
+#if defined(OVERLY_CONSERVATIVE_PTD_MGMT)
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_swtch_optim_stats
+#endif
+	movl	_IdlePTD, %ecx
+	movl	%cr3, %eax
+	cmpl	%ecx, %eax
+	je		2f
+#if defined(SWTCH_OPTIM_STATS)
+	decl	_swtch_optim_stats
+	incl	_tlb_flush_count
+#endif
+	movl	%ecx, %cr3
+2:
+#endif
 
 	/* update common_tss.tss_esp0 pointer */
 #ifdef VM86
 	movl	_my_tr, %esi
 #endif /* VM86 */
-	movl	$_common_tss, %eax
-	movl	%esp, TSS_ESP0(%eax)
+	movl	%esp, _common_tss + TSS_ESP0
 
 #ifdef VM86
 	btrl	%esi, _private_tss
@@ -576,16 +598,28 @@ swtch_com:
 
 	movl	%eax,P_BACK(%ecx) 		/* isolate process to run */
 	movl	P_ADDR(%ecx),%edx
-	movl	PCB_CR3(%edx),%ebx
 
 #ifdef SMP
+	movl	PCB_CR3(%edx),%ebx
 	/* Grab the private PT pointer from the outgoing process's PTD */
 	movl	$_PTD, %esi
 	movl	4*MPPTDI(%esi), %eax		/* fetch cpu's prv pt */
-#endif /* SMP */
-
+#else
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_swtch_optim_stats
+#endif
 	/* switch address space */
+	movl	%cr3,%ebx
+	cmpl	PCB_CR3(%edx),%ebx
+	je		4f
+#if defined(SWTCH_OPTIM_STATS)
+	decl	_swtch_optim_stats
+	incl	_tlb_flush_count
+#endif
+	movl	PCB_CR3(%edx),%ebx
+#endif /* SMP */
 	movl	%ebx,%cr3
+4:
 
 #ifdef SMP
 	/* Copy the private PT to the new process's PTD */
@@ -597,6 +631,9 @@ swtch_com:
 	 */
 	movl	%eax, 4*MPPTDI(%esi)		/* restore cpu's prv page */
 
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	/* XXX: we have just changed the page tables.. reload.. */
 	movl	%ebx, %cr3
 #endif /* SMP */
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index d6db6e6..0aeefb2 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)machdep.c	7.4 (Berkeley) 6/3/91
- *	$Id: machdep.c,v 1.277 1997/12/04 14:35:39 jkh Exp $
+ *	$Id: machdep.c,v 1.278 1997/12/04 21:21:24 jmg Exp $
  */
 
 #include "apm.h"
@@ -150,6 +150,14 @@ int	msgbufmapped = 0;		/* set when safe to use msgbuf */
 int _udatasel, _ucodesel;
 u_int	atdevbase;
 
+#if defined(SWTCH_OPTIM_STATS)
+extern int swtch_optim_stats;
+SYSCTL_INT(_debug, OID_AUTO, swtch_optim_stats,
+	CTLFLAG_RD, &swtch_optim_stats, 0, "");
+SYSCTL_INT(_debug, OID_AUTO, tlb_flush_count,
+	CTLFLAG_RD, &tlb_flush_count, 0, "");
+#endif
+
 
 int physmem = 0;
 int cold = 1;
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 2a8561f..0286bdb 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -39,7 +39,7 @@
  * SUCH DAMAGE.
  *
  *	from:	@(#)pmap.c	7.7 (Berkeley)	5/12/91
- *	$Id: pmap.c,v 1.172 1997/11/07 19:58:34 tegge Exp $
+ *	$Id: pmap.c,v 1.173 1997/11/20 19:30:31 bde Exp $
  */
 
 /*
@@ -1116,6 +1116,28 @@ pmap_unuse_pt(pmap, va, mpte)
 	return pmap_unwire_pte_hold(pmap, mpte);
 }
 
+#if !defined(SMP)
+void
+pmap_pinit0(pmap)
+	struct pmap *pmap;
+{
+	pmap->pm_pdir =
+		(pd_entry_t *)kmem_alloc_pageable(kernel_map, PAGE_SIZE);
+	pmap_kenter((vm_offset_t) pmap->pm_pdir, (vm_offset_t) IdlePTD);
+	pmap->pm_flags = 0;
+	pmap->pm_count = 1;
+	pmap->pm_ptphint = NULL;
+	TAILQ_INIT(&pmap->pm_pvlist);
+}
+#else
+void
+pmap_pinit0(pmap)
+	struct pmap *pmap;
+{
+	pmap_pinit(pmap);
+}
+#endif
+
 /*
  * Initialize a preallocated and zeroed pmap structure,
  * such as one in a vmspace structure.
@@ -3247,6 +3269,9 @@ pmap_mincore(pmap, addr)
 void
 pmap_activate(struct proc *p)
 {
+#if defined(SWTCH_OPTIM_STATS)
+	++tlb_flush_count;
+#endif
 	load_cr3(p->p_addr->u_pcb.pcb_cr3 =
 		vtophys(p->p_vmspace->vm_pmap.pm_pdir));
 }
diff --git a/sys/amd64/amd64/support.S b/sys/amd64/amd64/support.S
index 2ae3e20..3b9970f 100644
--- a/sys/amd64/amd64/support.S
+++ b/sys/amd64/amd64/support.S
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: support.s,v 1.56 1997/08/09 00:02:44 dyson Exp $
+ *	$Id: support.s,v 1.57 1997/09/02 20:05:30 bde Exp $
  */
 
 #include "npx.h"
@@ -1517,6 +1517,9 @@ ENTRY(rcr3)
 
 /* void load_cr3(caddr_t cr3) */
 ENTRY(load_cr3)
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	4(%esp),%eax
 	movl	%eax,%cr3
 	ret
diff --git a/sys/amd64/amd64/support.s b/sys/amd64/amd64/support.s
index 2ae3e20..3b9970f 100644
--- a/sys/amd64/amd64/support.s
+++ b/sys/amd64/amd64/support.s
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: support.s,v 1.56 1997/08/09 00:02:44 dyson Exp $
+ *	$Id: support.s,v 1.57 1997/09/02 20:05:30 bde Exp $
  */
 
 #include "npx.h"
@@ -1517,6 +1517,9 @@ ENTRY(rcr3)
 
 /* void load_cr3(caddr_t cr3) */
 ENTRY(load_cr3)
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	4(%esp),%eax
 	movl	%eax,%cr3
 	ret
diff --git a/sys/amd64/amd64/swtch.s b/sys/amd64/amd64/swtch.s
index 4d57b64..df0bda8 100644
--- a/sys/amd64/amd64/swtch.s
+++ b/sys/amd64/amd64/swtch.s
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.63 1997/09/21 15:03:58 peter Exp $
+ *	$Id: swtch.s,v 1.64 1997/10/10 09:44:06 peter Exp $
  */
 
 #include "npx.h"
@@ -86,6 +86,11 @@ _hlt_vector:	.long	_default_halt	/* pointer to halt routine */
 
 	.globl	_want_resched
 _want_resched:	.long	0		/* we need to re-run the scheduler */
+#if defined(SWTCH_OPTIM_STATS)
+	.globl	_swtch_optim_stats, _tlb_flush_count
+_swtch_optim_stats:	.long	0		/* number of _swtch_optims */
+_tlb_flush_count:	.long	0
+#endif
 
 	.text
 /*
@@ -252,6 +257,9 @@ _idle:
 	/* use our idleproc's "context" */
 	movl	_my_idlePTD,%ecx
 	movl	%ecx,%cr3
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	$_idlestack_top,%ecx
 	movl	%ecx,%esp
 
@@ -259,8 +267,7 @@ _idle:
 #ifdef VM86
 	movl	_my_tr, %esi
 #endif /* VM86 */
-	movl	$_common_tss, %eax
-	movl	%ecx, TSS_ESP0(%eax)
+	movl	%ecx, _common_tss + TSS_ESP0
 
 #ifdef VM86
 	btrl	%esi, _private_tss
@@ -302,6 +309,9 @@ _idle:
 	.globl	idle_loop
 idle_loop:
 
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	%cr3,%eax			/* ouch! */
 	movl	%eax,%cr3
 
@@ -357,15 +367,27 @@ idle_loop:
 #else
 	xorl	%ebp,%ebp
 	movl	$HIDENAME(tmpstk),%esp
-	movl	_IdlePTD,%ecx
-	movl	%ecx,%cr3
+#if defined(OVERLY_CONSERVATIVE_PTD_MGMT)
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_swtch_optim_stats
+#endif
+	movl	_IdlePTD, %ecx
+	movl	%cr3, %eax
+	cmpl	%ecx, %eax
+	je		2f
+#if defined(SWTCH_OPTIM_STATS)
+	decl	_swtch_optim_stats
+	incl	_tlb_flush_count
+#endif
+	movl	%ecx, %cr3
+2:
+#endif
 
 	/* update common_tss.tss_esp0 pointer */
 #ifdef VM86
 	movl	_my_tr, %esi
 #endif /* VM86 */
-	movl	$_common_tss, %eax
-	movl	%esp, TSS_ESP0(%eax)
+	movl	%esp, _common_tss + TSS_ESP0
 
 #ifdef VM86
 	btrl	%esi, _private_tss
@@ -576,16 +598,28 @@ swtch_com:
 
 	movl	%eax,P_BACK(%ecx) 		/* isolate process to run */
 	movl	P_ADDR(%ecx),%edx
-	movl	PCB_CR3(%edx),%ebx
 
 #ifdef SMP
+	movl	PCB_CR3(%edx),%ebx
 	/* Grab the private PT pointer from the outgoing process's PTD */
 	movl	$_PTD, %esi
 	movl	4*MPPTDI(%esi), %eax		/* fetch cpu's prv pt */
-#endif /* SMP */
-
+#else
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_swtch_optim_stats
+#endif
 	/* switch address space */
+	movl	%cr3,%ebx
+	cmpl	PCB_CR3(%edx),%ebx
+	je		4f
+#if defined(SWTCH_OPTIM_STATS)
+	decl	_swtch_optim_stats
+	incl	_tlb_flush_count
+#endif
+	movl	PCB_CR3(%edx),%ebx
+#endif /* SMP */
 	movl	%ebx,%cr3
+4:
 
 #ifdef SMP
 	/* Copy the private PT to the new process's PTD */
@@ -597,6 +631,9 @@ swtch_com:
 	 */
 	movl	%eax, 4*MPPTDI(%esi)		/* restore cpu's prv page */
 
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	/* XXX: we have just changed the page tables.. reload.. */
 	movl	%ebx, %cr3
 #endif /* SMP */
diff --git a/sys/amd64/include/cpufunc.h b/sys/amd64/include/cpufunc.h
index 3b7eb9c..4143dce 100644
--- a/sys/amd64/include/cpufunc.h
+++ b/sys/amd64/include/cpufunc.h
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: cpufunc.h,v 1.3 1997/09/05 20:20:31 smp Exp smp $
+ *	$Id: cpufunc.h,v 1.72 1997/09/07 22:01:27 fsmp Exp $
  */
 
 /*
@@ -45,6 +45,9 @@
 
 #include <machine/lock.h>
 
+#if defined(SWTCH_OPTIM_STATS)
+extern int tlb_flush_count;
+#endif
 
 #ifdef	__GNUC__
 
@@ -234,6 +237,9 @@ invltlb(void)
 	 */
 	__asm __volatile("movl %%cr3, %0; movl %0, %%cr3" : "=r" (temp)
 			 : : "memory");
+#if defined(SWTCH_OPTIM_STATS)
+	++tlb_flush_count;
+#endif
 }
 
 #endif	/* SMP */
diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index d6db6e6..0aeefb2 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)machdep.c	7.4 (Berkeley) 6/3/91
- *	$Id: machdep.c,v 1.277 1997/12/04 14:35:39 jkh Exp $
+ *	$Id: machdep.c,v 1.278 1997/12/04 21:21:24 jmg Exp $
  */
 
 #include "apm.h"
@@ -150,6 +150,14 @@ int	msgbufmapped = 0;		/* set when safe to use msgbuf */
 int _udatasel, _ucodesel;
 u_int	atdevbase;
 
+#if defined(SWTCH_OPTIM_STATS)
+extern int swtch_optim_stats;
+SYSCTL_INT(_debug, OID_AUTO, swtch_optim_stats,
+	CTLFLAG_RD, &swtch_optim_stats, 0, "");
+SYSCTL_INT(_debug, OID_AUTO, tlb_flush_count,
+	CTLFLAG_RD, &tlb_flush_count, 0, "");
+#endif
+
 
 int physmem = 0;
 int cold = 1;
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index 2a8561f..0286bdb 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -39,7 +39,7 @@
  * SUCH DAMAGE.
  *
  *	from:	@(#)pmap.c	7.7 (Berkeley)	5/12/91
- *	$Id: pmap.c,v 1.172 1997/11/07 19:58:34 tegge Exp $
+ *	$Id: pmap.c,v 1.173 1997/11/20 19:30:31 bde Exp $
  */
 
 /*
@@ -1116,6 +1116,28 @@ pmap_unuse_pt(pmap, va, mpte)
 	return pmap_unwire_pte_hold(pmap, mpte);
 }
 
+#if !defined(SMP)
+void
+pmap_pinit0(pmap)
+	struct pmap *pmap;
+{
+	pmap->pm_pdir =
+		(pd_entry_t *)kmem_alloc_pageable(kernel_map, PAGE_SIZE);
+	pmap_kenter((vm_offset_t) pmap->pm_pdir, (vm_offset_t) IdlePTD);
+	pmap->pm_flags = 0;
+	pmap->pm_count = 1;
+	pmap->pm_ptphint = NULL;
+	TAILQ_INIT(&pmap->pm_pvlist);
+}
+#else
+void
+pmap_pinit0(pmap)
+	struct pmap *pmap;
+{
+	pmap_pinit(pmap);
+}
+#endif
+
 /*
  * Initialize a preallocated and zeroed pmap structure,
  * such as one in a vmspace structure.
@@ -3247,6 +3269,9 @@ pmap_mincore(pmap, addr)
 void
 pmap_activate(struct proc *p)
 {
+#if defined(SWTCH_OPTIM_STATS)
+	++tlb_flush_count;
+#endif
 	load_cr3(p->p_addr->u_pcb.pcb_cr3 =
 		vtophys(p->p_vmspace->vm_pmap.pm_pdir));
 }
diff --git a/sys/i386/i386/support.s b/sys/i386/i386/support.s
index 2ae3e20..3b9970f 100644
--- a/sys/i386/i386/support.s
+++ b/sys/i386/i386/support.s
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: support.s,v 1.56 1997/08/09 00:02:44 dyson Exp $
+ *	$Id: support.s,v 1.57 1997/09/02 20:05:30 bde Exp $
  */
 
 #include "npx.h"
@@ -1517,6 +1517,9 @@ ENTRY(rcr3)
 
 /* void load_cr3(caddr_t cr3) */
 ENTRY(load_cr3)
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	4(%esp),%eax
 	movl	%eax,%cr3
 	ret
diff --git a/sys/i386/i386/swtch.s b/sys/i386/i386/swtch.s
index 4d57b64..df0bda8 100644
--- a/sys/i386/i386/swtch.s
+++ b/sys/i386/i386/swtch.s
@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: swtch.s,v 1.63 1997/09/21 15:03:58 peter Exp $
+ *	$Id: swtch.s,v 1.64 1997/10/10 09:44:06 peter Exp $
  */
 
 #include "npx.h"
@@ -86,6 +86,11 @@ _hlt_vector:	.long	_default_halt	/* pointer to halt routine */
 
 	.globl	_want_resched
 _want_resched:	.long	0		/* we need to re-run the scheduler */
+#if defined(SWTCH_OPTIM_STATS)
+	.globl	_swtch_optim_stats, _tlb_flush_count
+_swtch_optim_stats:	.long	0		/* number of _swtch_optims */
+_tlb_flush_count:	.long	0
+#endif
 
 	.text
 /*
@@ -252,6 +257,9 @@ _idle:
 	/* use our idleproc's "context" */
 	movl	_my_idlePTD,%ecx
 	movl	%ecx,%cr3
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	$_idlestack_top,%ecx
 	movl	%ecx,%esp
 
@@ -259,8 +267,7 @@ _idle:
 #ifdef VM86
 	movl	_my_tr, %esi
 #endif /* VM86 */
-	movl	$_common_tss, %eax
-	movl	%ecx, TSS_ESP0(%eax)
+	movl	%ecx, _common_tss + TSS_ESP0
 
 #ifdef VM86
 	btrl	%esi, _private_tss
@@ -302,6 +309,9 @@ _idle:
 	.globl	idle_loop
 idle_loop:
 
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	movl	%cr3,%eax			/* ouch! */
 	movl	%eax,%cr3
 
@@ -357,15 +367,27 @@ idle_loop:
 #else
 	xorl	%ebp,%ebp
 	movl	$HIDENAME(tmpstk),%esp
-	movl	_IdlePTD,%ecx
-	movl	%ecx,%cr3
+#if defined(OVERLY_CONSERVATIVE_PTD_MGMT)
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_swtch_optim_stats
+#endif
+	movl	_IdlePTD, %ecx
+	movl	%cr3, %eax
+	cmpl	%ecx, %eax
+	je		2f
+#if defined(SWTCH_OPTIM_STATS)
+	decl	_swtch_optim_stats
+	incl	_tlb_flush_count
+#endif
+	movl	%ecx, %cr3
+2:
+#endif
 
 	/* update common_tss.tss_esp0 pointer */
 #ifdef VM86
 	movl	_my_tr, %esi
 #endif /* VM86 */
-	movl	$_common_tss, %eax
-	movl	%esp, TSS_ESP0(%eax)
+	movl	%esp, _common_tss + TSS_ESP0
 
 #ifdef VM86
 	btrl	%esi, _private_tss
@@ -576,16 +598,28 @@ swtch_com:
 
 	movl	%eax,P_BACK(%ecx) 		/* isolate process to run */
 	movl	P_ADDR(%ecx),%edx
-	movl	PCB_CR3(%edx),%ebx
 
 #ifdef SMP
+	movl	PCB_CR3(%edx),%ebx
 	/* Grab the private PT pointer from the outgoing process's PTD */
 	movl	$_PTD, %esi
 	movl	4*MPPTDI(%esi), %eax		/* fetch cpu's prv pt */
-#endif /* SMP */
-
+#else
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_swtch_optim_stats
+#endif
 	/* switch address space */
+	movl	%cr3,%ebx
+	cmpl	PCB_CR3(%edx),%ebx
+	je		4f
+#if defined(SWTCH_OPTIM_STATS)
+	decl	_swtch_optim_stats
+	incl	_tlb_flush_count
+#endif
+	movl	PCB_CR3(%edx),%ebx
+#endif /* SMP */
 	movl	%ebx,%cr3
+4:
 
 #ifdef SMP
 	/* Copy the private PT to the new process's PTD */
@@ -597,6 +631,9 @@ swtch_com:
 	 */
 	movl	%eax, 4*MPPTDI(%esi)		/* restore cpu's prv page */
 
+#if defined(SWTCH_OPTIM_STATS)
+	incl	_tlb_flush_count
+#endif
 	/* XXX: we have just changed the page tables.. reload.. */
 	movl	%ebx, %cr3
 #endif /* SMP */
diff --git a/sys/i386/include/cpufunc.h b/sys/i386/include/cpufunc.h
index 3b7eb9c..4143dce 100644
--- a/sys/i386/include/cpufunc.h
+++ b/sys/i386/include/cpufunc.h
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: cpufunc.h,v 1.3 1997/09/05 20:20:31 smp Exp smp $
+ *	$Id: cpufunc.h,v 1.72 1997/09/07 22:01:27 fsmp Exp $
  */
 
 /*
@@ -45,6 +45,9 @@
 
 #include <machine/lock.h>
 
+#if defined(SWTCH_OPTIM_STATS)
+extern int tlb_flush_count;
+#endif
 
 #ifdef	__GNUC__
 
@@ -234,6 +237,9 @@ invltlb(void)
 	 */
 	__asm __volatile("movl %%cr3, %0; movl %0, %%cr3" : "=r" (temp)
 			 : : "memory");
+#if defined(SWTCH_OPTIM_STATS)
+	++tlb_flush_count;
+#endif
 }
 
 #endif	/* SMP */
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index d4ea42b..620e1b9 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -39,7 +39,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)init_main.c	8.9 (Berkeley) 1/21/94
- * $Id: init_main.c,v 1.77 1997/12/06 04:11:09 sef Exp $
+ * $Id: init_main.c,v 1.78 1997/12/12 04:00:57 dyson Exp $
  */
 
 #include "opt_devfs.h"
@@ -401,7 +401,7 @@ proc0_init(dummy)
 	/* Allocate a prototype map so we have something to fork. */
 	p->p_vmspace = &vmspace0;
 	vmspace0.vm_refcnt = 1;
-	pmap_pinit(&vmspace0.vm_pmap);
+	pmap_pinit0(&vmspace0.vm_pmap);
 	vm_map_init(&vmspace0.vm_map, round_page(VM_MIN_ADDRESS),
 	    trunc_page(VM_MAXUSER_ADDRESS), TRUE);
 	vmspace0.vm_map.pmap = &vmspace0.vm_pmap;
diff --git a/sys/vm/pmap.h b/sys/vm/pmap.h
index 2c9697a..291cb01 100644
--- a/sys/vm/pmap.h
+++ b/sys/vm/pmap.h
@@ -61,7 +61,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: pmap.h,v 1.23 1997/08/05 22:07:21 dyson Exp $
+ * $Id: pmap.h,v 1.24 1997/08/05 23:03:24 dyson Exp $
  */
 
 /*
@@ -113,6 +113,7 @@ void		 pmap_pageable __P((pmap_t, vm_offset_t, vm_offset_t,
 		    boolean_t));
 vm_offset_t	 pmap_phys_address __P((int));
 void		 pmap_pinit __P((pmap_t));
+void		 pmap_pinit0 __P((pmap_t));
 void		 pmap_protect __P((pmap_t, vm_offset_t, vm_offset_t,
 		    vm_prot_t));
 void		 pmap_qenter __P((vm_offset_t, vm_page_t *, int));