Revive backed out pmap related changes from Feb 2002. The highlights are:

- It actually works this time, honest!
- Fine grained TLB shootdowns for SMP on i386.  IPI's are very expensive,
  so try and optimize things where possible.
- Introduce ranged shootdowns that can be done as a single IPI.
- PG_G support for i386
- Specific-cpu targeted shootdowns.  For example, there is no sense in
  globally purging the TLB cache for where we are stealing a page from
  the local unshared process on the local cpu.  Use pm_active to track
  this.
- Add some instrumentation for the tlb shootdown code.
- Rip out SMP code from <machine/cpufunc.h>
- Try and fix some very bogus PG_G and PG_PS interactions that were bad
  enough to cause vm86 bios calls to break.  vm86 depended on our existing
  bugs and this was the cause of the VESA panics last time.
- Fix the silly one-line error that caused the 'panic: bad pte' last time.
- Fix a couple of other silly one-line errors that should have caused more
  pain than they did.

Some more work is needed:
- pmap_{zero,copy}_page[_idle].  These can be done without IPI's if we
  have a hook in cpu_switch.
- The IPI handlers need some cleanup.  I have a bogus %ds load that can
  be avoided.
- APTD handling is rather bogus and appears to be a large source of
  global TLB IPI shootdowns for no really good reason.

I see speedups of between 1.5% and ~4% on buildworlds in a while 1 loop.
I expect to see a bigger difference when there is significant pageout
activity or the system otherwise has memory shortages.

I have backed out a few optimizations that I had been using over the last
few days in order to be a little more conservative.  I'll revisit these
again over the next few days as the dust settles.

New option:  DISABLE_PG_G - In case I missed something.

1 files changed, 5 insertions, 4 deletions

diff --git a/sys/i386/include/pmap.h b/sys/i386/include/pmap.h
index e6ac669..e0789fc 100644
--- a/sys/i386/include/pmap.h
+++ b/sys/i386/include/pmap.h
@@ -151,7 +151,7 @@ extern pt_entry_t PTmap[], APTmap[];
 extern pd_entry_t PTD[], APTD[];
 extern pd_entry_t PTDpde, APTDpde;
 
-extern pd_entry_t IdlePTD;	/* physical address of "Idle" state directory */
+extern pd_entry_t *IdlePTD;	/* physical address of "Idle" state directory */
 #endif
 
 #ifdef _KERNEL
@@ -253,14 +253,15 @@ extern char *ptvmmap;		/* poor name! */
 extern vm_offset_t virtual_avail;
 extern vm_offset_t virtual_end;
 
-void	pmap_bootstrap( vm_offset_t, vm_offset_t);
+void	pmap_bootstrap(vm_offset_t, vm_offset_t);
 void	*pmap_mapdev(vm_offset_t, vm_size_t);
 void	pmap_unmapdev(vm_offset_t, vm_size_t);
 pt_entry_t *pmap_pte(pmap_t, vm_offset_t) __pure2;
 vm_page_t pmap_use_pt(pmap_t, vm_offset_t);
-#ifdef SMP
 void	pmap_set_opt(void);
-#endif
+void	pmap_invalidate_page(pmap_t, vm_offset_t);
+void	pmap_invalidate_range(pmap_t, vm_offset_t, vm_offset_t);
+void	pmap_invalidate_all(pmap_t);
 
 #endif /* _KERNEL */