Synopsis: SMP amd64 system exhibits excessive cpu shootdown IPIs

State-Changed-From-To: open->analyzed
State-Changed-By: chs@netbsd.org
State-Changed-When: Sun, 09 Oct 2005 16:43:03 +0000
State-Changed-Why:
this is due to the DEBUG code in uvm_map.c.  the loop calling pmap_extract()
to verify that there are no pmap entries in a range where there shouldn't be
make the pmap code do an awful lot of TLB invalidation IPIs.  eventually
we should rewrite the amd64 pmap to have a KSEG0-like region where it can
access any physical page without needing to map it again.  that will fix
this problem and also be a nice improvement in general.  for now, just
don't use DEBUG MP kernels if you want the system to perform well.