Re: [v6, 1/2] raid6/altivec: Add vpermxor implementation for raid6 Q syndrome

On Fri, 2017-08-04 at 03:42:32 UTC, Matt Brown wrote:

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 <redacted>
Reviewed-by: Daniel Axtens <redacted>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/751ba79cc552c146595cd439b21c4f

cheers