cvs commit: src/sys/i386/i386 pmap.c src/sys/i386/include pmap.h

Peter Wemm peter at
Tue Jun 29 08:57:10 PDT 2004

peter       2004-06-29 15:57:05 UTC

  FreeBSD src repository

  Modified files:
    sys/i386/i386        pmap.c 
    sys/i386/include     pmap.h 
  Reduce the size of pv entries by 15%.  This saves 1MB of KVA for mapping
  pv entries per 1GB of user virtual memory.  (eg: if we had 1GB file was
  mmaped into 30 processes, that would theoretically reduce the KVA demand by
  30MB for pv entries.  In reality though, we limit pv entries so we don't
  have that many at once.)
  We used to store the vm_page_t for the page table page.  But we recently
  had the pa of the ptp, or can calculate it fairly quickly.  If we wanted
  to avoid the shift/mask operation in pmap_pde(), we could recover the
  pa but that means we have to store it for a while.
  This does not measurably change performance.
  Suggested by:  alc
  Tested by:  alc
  Revision  Changes    Path
  1.479     +15 -16    src/sys/i386/i386/pmap.c
  1.112     +0 -1      src/sys/i386/include/pmap.h

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