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

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Message-ID: <CAPoR37bE=WfpfKYdYz-L3y7XNjeTqYj7BQm=MoEVe8V08360ZA@mail.gmail.com>
Date:   Thu, 10 Aug 2017 09:41:16 +1000
From:   Matt Brown <matthew.brown.dev@...il.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" 
        <linuxppc-dev@...ts.ozlabs.org>, Daniel Axtens <dja@...ens.net>,
        gayatri.kammela@...el.com, shli@...com, fenghua.yu@...el.com,
        megha.dey@...ux.intel.com, schwidefsky@...ibm.com,
        linux-kernel@...r.kernel.org, anup.patel@...adcom.com
Subject: Re: [v6 1/2] raid6/altivec: Add vpermxor implementation for raid6 Q syndrome

On Wed, Aug 9, 2017 at 11:26 PM, Michael Ellerman <mpe@...erman.id.au> wrote:
> Matt Brown <matthew.brown.dev@...il.com> writes:
>
>> 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@...il.com>
>> Reviewed-by: Daniel Axtens <dja@...ens.net>
>> ---
>> v6:
>>       - added vpermxor files to .gitignore
>>       - fixup whitespace
>>       - added vpermxor objs to test/Makefile
>> v5:
>>       - moved altivec.uc fix into other patch in series
>> ---
>>  include/linux/raid/pq.h |   4 ++
>>  lib/raid6/.gitignore    |   1 +
>>  lib/raid6/Makefile      |  27 ++++++++++++-
>>  lib/raid6/algos.c       |   4 ++
>>  lib/raid6/test/Makefile |  17 +++++++-
>>  lib/raid6/vpermxor.uc   | 104 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  6 files changed, 154 insertions(+), 3 deletions(-)
>>  create mode 100644 lib/raid6/vpermxor.uc
>
> This version at least is not Cc'ed to any of the folks that
> get_maintainers.pl identifies for these files:
>
> $ ./scripts/get_maintainer.pl -f lib/raid6
> shli@...com
> gayatri.kammela@...el.com
> fenghua.yu@...el.com
> megha.dey@...ux.intel.com
> schwidefsky@...ibm.com
> anup.patel@...adcom.com
> linux-kernel@...r.kernel.org
>
>
> This seems like mostly a list of random folks who've touched this code,
> but maybe some of them would have comments?
>

Ah my bad. I've CC'ed them into this email chain.
Apologies for not including you guys in the original email.
Here is a link to the patchworks patch:
http://patchwork.ozlabs.org/patch/797576/

Thanks,
Matt Brown