cvs commit: src/sys/kern vfs_vnops.c

David Rhodus drhodus at
Mon Mar 29 07:22:30 PST 2004

drhodus     2004/03/29 07:21:42 PST

DragonFly src repository

  Modified files:
    sys/kern             vfs_vnops.c 
  *	Change the offset alignment in vn_rdwe_inchunks()
  	This is primarily used by the ELF image activator.
  FreeBSD src repository
    Modified files:
      sys/kern             vfs_vnops.c
    Align the offset in vn_rdwr_inchunks() so that at most the first and
    the last chunk are misaligned relative to a MAXBSIZE byte boundary.
    vn_rdwr_inchunks() is used mainly for elf core dumps, and elf sections
    are usually perfectly misaligned relative to MAXBSIZE, and chunking
    prevents the file system from doing much realigning.
    This gives a surprisingly large speedup for core dumps -- from 50 to
    13 seconds for a 512MB core dump here.  The pessimization was mostly
    from an interaction of the misalignment with IO_DIRECT.  It increased
    the number of i/o's for each chunk by a factor of 5 (3 writes and 2
    read-before-writes instead of 1 write).
  Revision  Changes    Path
  1.17      +12 -2     src/sys/kern/vfs_vnops.c

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