kvm on amd64 - >6G?

[Barry Boes]

I could apply such a patch to my servers, but there are two disadvantages :
  o who wants to apply kernel patches to mission critical servers? Isn't
     that a linux thing (joke!) 
  o what about apps like the linuxulator that might not stand for this?

On the tunable option : with today's kmem_size and kmem_size_max
tunables, would there also be a need to tune the portion of address
space available to kmem?

Thanks,
Barry

Kris Kennaway writes:
 > Barry Boes wrote:
 > > With the advent of ZFS, Solaris users are devoting 30G or more to
 > > their ARC caches today.  If FreeBSD 8 is going to up the KVM size, is
 > > there a reason to not increase the limit to something that will not be
 > > reached in the lifetime of 8?  100GB?
 > 
 > It's easily configurable on HEAD.  From an email alc sent me:
 > 
 > ----
 > This:
 > 
 > Index: amd64/include/pmap.h
 > ===================================================================
 > --- amd64/include/pmap.h        (revision 180373)
 > +++ amd64/include/pmap.h        (working copy)
 > @@ -111,7 +111,7 @@
 > 
 > /* Initial number of kernel page tables. */
 > #ifndef NKPT
 > -#define        NKPT            32
 > +#define        NKPT            1023
 > #endif
 > 
 > #define NKPML4E                1               /* number of kernel PML4 
 > slots */
 > Index: amd64/include/vmparam.h
 > ===================================================================
 > --- amd64/include/vmparam.h     (revision 180373)
 > +++ amd64/include/vmparam.h     (working copy)
 > @@ -163,7 +163,7 @@
 >   */
 > 
 > #define        VM_MAX_KERNEL_ADDRESS   KVADDR(KPML4I, NPDPEPG-1, 
 > NPDEPG-1, NPTEPG-1)
 > -#define        VM_MIN_KERNEL_ADDRESS   KVADDR(KPML4I, NPDPEPG-7, 0, 0)
 > +#define        VM_MIN_KERNEL_ADDRESS   KVADDR(KPML4I, 0, 0, 0)
 > 
 > #define        DMAP_MIN_ADDRESS        KVADDR(DMPML4I, 0, 0, 0)
 > #define        DMAP_MAX_ADDRESS        KVADDR(DMPML4I+1, 0, 0, 0)
 > 
 > will now get you this:
 > 
 > vm.kvm_free: 547729960960
 > vm.kvm_size: 549755809792
 > 
 > on HEAD.  :-)
 > ----
 > 
 > Kris