cvs commit: src/sys/vm vm_fault.c

Alan Cox alc at
Sat Aug 25 11:43:16 PDT 2007

alc         2007-08-25 18:43:16 UTC

  FreeBSD src repository

  Modified files:        (Branch: RELENG_6)
    sys/vm               vm_fault.c 
  MFC revision 1.234
    Eliminate the special case handling of OBJT_DEVICE objects in
    vm_fault_additional_pages() that was introduced in revision 1.47.  Then
    as now, it is unnecessary because dev_pager_haspage() returns zero for
    both the number of pages to read ahead and read behind, producing the
    same exact behavior by vm_fault_additional_pages() as the special case
  MFC revision 1.235
    Two changes to vm_fault_additional_pages():
    1. Rewrite the backward scan.  Specifically, reverse the order in which
       pages are allocated so that upon failure it is never necessary to
       free pages that were just allocated.  Moreover, any allocated pages
       can be put to use.  This makes the backward scan behave just like the
       forward scan.
    2. Eliminate an explicit, unsynchronized check for low memory before
       calling vm_page_alloc().  It serves no useful purpose.  It is, in
       effect, optimizing the uncommon case at the expense of the common
  Revision   Changes    Path  +11 -28    src/sys/vm/vm_fault.c

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