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cvs commit: src/sys/kern src/sys/sys src/sys/checkpt

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 18 Nov 2004 05:09:55 -0800 (PST)

dillon      2004/11/18 05:09:55 PST

DragonFly src repository

  Modified files:
    sys/kern             imgact_elf.c kern_descrip.c 
    sys/sys              kern_syscall.h vnode.h 
    sys/checkpt          checkpt.c 
  Lots of bug fixes to the checkpointing code.  The big fix is that you can
  now checkpoint a program that you have checkpoint-restored.  i.e. you run
  program X, you checkpoint it, you checkpoint-restore X from the checkpoint,
  and then you checkpoint it again.  The issue here is the when a checkpointed
  program is restored the checkpoint file is used to map portions of the image
  of the restored program.  If you then tried to checkpoint the restored image
  the system would overwrite or destroy the original checkpoint file and
  the new checkpoint file would have references to the old file (now
  non-existant) file.  Any attempt to restore the recursed checkpoint would
  result in a seg-fault.  That is now fixed.
  * Remove the previous checkpoint file before saving the new one.  If the
    program we are checkpointing happens to be a checkpoint restore from the
    same file then overwriting the file would wind up corrupting the
    image set we are trying to save.
  * When checkpointing a program that has been checkpoint-restored do not
    attempt to save the file handles for the vnode representing the
    checkpoint-restored program's own checkpoint file (which is a good chunk
    of its backing store), because this vnode is likely to be destroyed the
    moment we close the handle, since we are likely replacing the previous
    checkpoint file.  Instead, the backing store representing the old
    checkpoint file is copied to the new one.
  * Re-checkpointing a program (hitting ^E multiple times) now properly
    replaces the checkpoint file.
  * Properly close any file descriptors from the checkpt(1) program itself
    when restoring a checkpointed program, properly replace any file descriptors
    that need replacing.
  * Properly replace p_comm[] when restoring a checkpoint file, so checkpointing
    again saves under the same program name.  'ps' output is still wrong,
  * Add an iterator to the checkpoint file, accessible via kern.ckptfile,
    so successive checkpoints save to a blah.ckpt.1, blah.ckpt.2, etc,
    rather then always overwriting blah.ckpt (the iterator could be saved
    in the proc structure).
  * Add back as a 'feature' the ability for the new checkpoint file to
    reference the old one.  That is, each new checkpoint file would represent
    a delta relative to the old one.  This might be useful when checkpointing
    programs with ever growing data setse so as not to have to copy the
    entire contents of the program to the checkpoint file each time you want
    to make a new checkpoint.  It would be hell on the VM system, but it
    would work.
  * Add an option to checkpt(1) so you can checkpoint-restore-enter-gdb all
    in one go, to be able to debug a checkpointed file more easily.
  Inspired by: Brook Davis's HPC presentation.  He expressed an interest in
  	     possibly porting the checkpoint code so I figure I ought to
  	     fix it up.
  Revision  Changes    Path
  1.24      +21 -2     src/sys/kern/imgact_elf.c
  1.32      +6 -1      src/sys/kern/kern_descrip.c
  1.21      +1 -0      src/sys/sys/kern_syscall.h
  1.27      +1 -1      src/sys/sys/vnode.h
  1.7       +67 -12    src/sys/checkpt/checkpt.c


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