cvs commit: src/sys/kern imgact_elf.c src/sys/vm vm_extern.h vm_glue.c

[Alan Cox]

alc         2005-12-16 18:34:14 UTC

  FreeBSD src repository

  Modified files:
    sys/kern             imgact_elf.c 
    sys/vm               vm_extern.h vm_glue.c 
  Log:
  Use sf_buf_alloc() instead of vm_map_find() on exec_map to create the
  ephemeral mappings that are used as the source for three copy
  operations from kernel space to user space.  There are two reasons for
  making this change: (1) Under heavy load exec_map can fill up causing
  vm_map_find() to fail.  When it fails, the nascent process is aborted
  (SIGABRT).  Whereas, this reimplementation using sf_buf_alloc()
  sleeps.  (2) Although it is possible to sleep on vm_map_find()'s
  failure until address space becomes available (see kmem_alloc_wait()),
  using sf_buf_alloc() is faster.  Furthermore, the reimplementation
  uses a CPU private mapping, avoiding a TLB shootdown on
  multiprocessors.
  
  Problem uncovered by: kris@
  Reviewed by: tegge@
  MFC after: 3 weeks
  
  Revision  Changes    Path
  1.167     +29 -61    src/sys/kern/imgact_elf.c
  1.77      +2 -0      src/sys/vm/vm_extern.h
  1.214     +72 -0     src/sys/vm/vm_glue.c