[PATCH 00/16] makedumpfile-1.5.0-rc: Introduce cyclic mode to fix memory usage.

[kumagai-atsushi@xxxxxxxxxxxxxxxxx (Atsushi Kumagai)]

Hello,

I post this patchset as release candidate of v1.5.0.
If there are no comments, I will release them as official version in a week.

Explanation:

  This version introduces the "cyclic mode" as a default running mode.

  Before this version, makedumpfile uses the amount of memory depending 
  on physical memory size, because it saves the analytical data for whole
  memory at a time.

  On the other hand, cyclic mode uses fixed amount of memory regardless of
  physical memory size, because this mode analyzes only constant region of
  memory per cycle as below:

    [v1.4.7 or before]
      cycle                       1
                    +-----------------     -----+
      vmcore        |                  ...      | 
                    +-----------------     -----+

    [v1.5.0]
      cycle           1   2   3   4    ...    N
                    +-----------------     -----+
      vmcore        |   |   |   |   |  ...  |   | 
                    +-----------------     -----+

  And, the number of cycles is represented as:
     
    N = physical memory size / (page size * bit per byte(8) * BUFSIZE_CYCLIC)
   
  BUFSIZE_CYCLIC is the buffer size for analysis, default size is 1 Mbyte.

  BTW, in v1.5.0, cyclic mode may cause some slow down of filtering process
  when N is large. 
  I'm going to improve this issue with new filtering logic (called mem_map array logic)
  in a future version.

  At least in v1.5.0, if you feel cyclic mode is slow, you can try 2 workarounds:

    1. Use old running mode with "--non-cyclic" option.

    2. Decrease the number of cycles by increasing BUFSIZE_CYCLIC with 
       "--cyclic-buffer" option.

  Please refer to the manual page for how to use these options.


I am waiting for your comments.


Thanks
Atsushi Kumagai