Re: Cost of XLogInsert CRC calculations

> -----Original Message-----
> From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
> Sent: 16 May 2005 17:36
> To: Mark Cave-Ayland (External)
> Cc: pgsql-hackers(at)postgresql(dot)org
> Subject: Re: [HACKERS] Cost of XLogInsert CRC calculations

(cut)

> I did some experimentation and concluded that gcc is screwing
> up big-time on optimizing the CRC64 code for 32-bit Intel.
> It does much better on every other architecture though.

Hi Tom,

Thanks very much for showing that the unint64 slowdown was caused by the
optimisation done by gcc - I've had a go at filing a bug with the gcc people
at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21617 so it would be
interesting see if they can solve this. Perhaps like you suggest, the short
term solution is to use the uint32 CRC64 code everywhere at the moment. I
hope to find some time later this week to write and test some CRC32
routines, and will post the results back to the list.

Many thanks,

Mark.

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