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lib/raid6/altivec: Add vpermxor implementation for raid6 Q syndrome

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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 <matthew.brown.dev@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
[mpe: Add VPERMXOR macro so we can build with old binutils]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Matt Brown
2017-08-04 13:42:32 +10:00
committed by Michael Ellerman
parent 7004263bd4
commit 751ba79cc5
7 changed files with 161 additions and 3 deletions
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4
include/linux/raid/pq.h
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@@ -107,6 +107,10 @@ extern const struct raid6_calls raid6_avx512x2;
extern const struct raid6_calls raid6_avx512x4;
extern const struct raid6_calls raid6_tilegx8;
extern const struct raid6_calls raid6_s390vx8;
extern const struct raid6_calls raid6_vpermxor1;
extern const struct raid6_calls raid6_vpermxor2;
extern const struct raid6_calls raid6_vpermxor4;
extern const struct raid6_calls raid6_vpermxor8;
struct raid6_recov_calls {
void (*data2)(int, size_t, int, int, void **);