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From: "Pierre C" on 7 Jun 2010 06:37
> On Sunday 30 May 2010 18:29:31 Greg Stark wrote:
>> On Sun, May 30, 2010 at 4:54 AM, Tom Lane <tgl(a)sss.pgh.pa.us> wrote:
>> > I read through that thread and couldn't find much discussion of
>> > alternative CRC implementations --- we spent all our time on arguing
>> > about whether we needed 64-bit CRC or not.

SSE4.2 has a hardware CRC32 instruction, this might be interesting to
use...

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From: Yeb Havinga on 7 Jun 2010 15:20
Florian Pflug wrote:
> On Jun 7, 2010, at 12:45 , Andres Freund wrote:
>
>> On Monday 07 June 2010 12:37:13 Pierre C wrote:
>>
>>>> On Sunday 30 May 2010 18:29:31 Greg Stark wrote:
>>>>
>>>>> On Sun, May 30, 2010 at 4:54 AM, Tom Lane <tgl(a)sss.pgh.pa.us> wrote:
>>>>>
>>>>>> I read through that thread and couldn't find much discussion of
>>>>>> alternative CRC implementations --- we spent all our time on arguing
>>>>>> about whether we needed 64-bit CRC or not.
>>>>>>
>>> SSE4.2 has a hardware CRC32 instruction, this might be interesting to
>>> use...
>>>
>> Different polynom unfortunately...
>>
>
> Since only the WAL uses CRC, I guess the polynomial could be changed though. pg_upgrade for example shouldn't care.
>
> RFC3385 compares different checksumming methods for use in iSCSI, and CRC32c (which uses the same polynomial as the SSE4.2 instruction) wins. Here's
> a link: http://www.faqs.org/rfcs/rfc3385.html
>
The linux kernel also uses it when it's availabe, see e.g.
http://tomoyo.sourceforge.jp/cgi-bin/lxr/source/arch/x86/crypto/crc32c-intel.c

regards,
Yeb Havinga


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From: "Pierre C" on 8 Jun 2010 06:10

> The linux kernel also uses it when it's availabe, see e.g.
> http://tomoyo.sourceforge.jp/cgi-bin/lxr/source/arch/x86/crypto/crc32c-intel.c

If you guys are interested I have a Core i7 here, could run a little
benchmark.

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