Eric Lee / smarc-fsl-linux-kernel

22 Apr, 2015

2 commits

  • a582564b2   md/raid6 algorithms: xor_syndrome() for SSE2 ... Browse Code »

    The second and (last) optimized XOR syndrome calculation. This version
    supports right and left side optimization. All CPUs with architecture
    older than Haswell will benefit from it.

    It should be noted that SSE2 movntdq kills performance for memory areas
    that are read and written simultaneously in chunks smaller than cache
    line size. So use movdqa instead for P/Q writes in sse21 and sse22 XOR
    functions.

    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
     

13 Dec, 2012

1 commit

12 Aug, 2010

1 commit

11 Aug, 2010

1 commit