Eric Lee / smarc-fsl-linux-kernel

22 Apr, 2015

2 commits

  • 9a5ce91d0   md/raid6 algorithms: xor_syndrome() for generic int ... Browse Code »

    Start the algorithms with the very basic one. It is left and right
    optimized. That means we can avoid all calculations for unneeded pages
    above the right stop offset. For pages below the left start offset we
    still need the syndrome multiplication but without reading data pages.

    Signed-off-by: Markus Stockhausen
    Signed-off-by: NeilBrown

    Markus Stockhausen
     
  • fe5cbc6e0   md/raid6 algorithms: delta syndrome functions ... Browse Code »

    v3: s-o-b comment, explanation of performance and descision for
    the start/stop implementation

    Implementing rmw functionality for RAID6 requires optimized syndrome
    calculation. Up to now we can only generate a complete syndrome. The
    target P/Q pages are always overwritten. With this patch we provide
    a framework for inplace P/Q modification. In the first place simply
    fill those functions with NULL values.

    xor_syndrome() has two additional parameters: start & stop. These
    will indicate the first and last page that are changing during a
    rmw run. That makes it possible to avoid several unneccessary loops
    and speed up calculation. The caller needs to implement the following
    logic to make the functions work.

    1) xor_syndrome(disks, start, stop, ...): "Remove" all data of source
    blocks inside P/Q between (and including) start and end.

    2) modify any block with start
    Signed-off-by: NeilBrown

    Markus Stockhausen
     

20 Oct, 2011

1 commit

11 Aug, 2010

1 commit