Eric Lee / smarc-fsl-linux-kernel

20 Mar, 2018

1 commit

  • 751ba79cc   lib/raid6/altivec: Add vpermxor implementation for raid6 Q syndrome ... Browse Code ยป

    This patch uses the vpermxor instruction to optimise the raid6 Q
    syndrome. This instruction was made available with POWER8, ISA version
    2.07. It allows for both vperm and vxor instructions to be done in a
    single instruction. This has been tested for correctness on a ppc64le
    vm with a basic RAID6 setup containing 5 drives.

    The performance benchmarks are from the raid6test in the
    /lib/raid6/test directory. These results are from an IBM Firestone
    machine with ppc64le architecture. The benchmark results show a 35%
    speed increase over the best existing algorithm for powerpc (altivec).
    The raid6test has also been run on a big-endian ppc64 vm to ensure it
    also works for big-endian architectures.

    Performance benchmarks:
    raid6: altivecx4 gen() 18773 MB/s
    raid6: altivecx8 gen() 19438 MB/s

    raid6: vpermxor4 gen() 25112 MB/s
    raid6: vpermxor8 gen() 26279 MB/s

    Signed-off-by: Matt Brown
    Reviewed-by: Daniel Axtens
    [mpe: Add VPERMXOR macro so we can build with old binutils]
    Signed-off-by: Michael Ellerman

    Matt Brown