From: | Yeb Havinga <yebhavinga(at)gmail(dot)com> |
---|---|
To: | Florian Pflug <fgp(at)phlo(dot)org> |
Cc: | Andres Freund <andres(at)anarazel(dot)de>, Pierre C <lists(at)peufeu(dot)com>, Greg Stark <gsstark(at)mit(dot)edu>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bruce Momjian <bruce(at)momjian(dot)us>, pgsql-hackers(at)postgresql(dot)org, singh(dot)gurjeet(at)gmail(dot)com |
Subject: | Re: Re: [RFC][PATCH]: CRC32 is limiting at COPY/CTAS/INSERT ... SELECT + speeding it up |
Date: | 2010-06-07 19:20:55 |
Message-ID: | 4C0D4697.2030501@gmail.com |
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Lists: | pgsql-hackers |
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(at)sss(dot)pgh(dot)pa(dot)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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