On E, 2005-05-16 at 12:12 +0100, Mark Cave-Ayland wrote: > > -----Original Message----- > > From: Mark Cave-Ayland [mailto:[EMAIL PROTECTED] > > Sent: 16 May 2005 09:04 > > To: 'Simon Riggs' > > Cc: 'Christopher Kings-Lynne'; 'Tom Lane'; 'Bruce Momjian'; > > 'pgsql-hackers@postgresql.org' > > Subject: RE: [HACKERS] Cost of XLogInsert CRC calculations >
> > Win32 UINT64: 0x782104059a01660 (crc0) ~158us > Win32 UINT32: 0x78210405 (crc1), 0x59a01660 (crc0) ~58us > FC1 UINT64: 0x782104059a01660 (crc0) ~76us > FC1 UINT32: 0x78210405 (crc1), 0x59a01660 (crc0) ~29us It would interesting to see how much of the time taken is actual algorithm and how much is getting at the data (i.e the fact that the page has to go through CPU at all, instead DMA'ing it to disk). In your test setup you probably have the whole thing in CPU cache already, but still it would be interesting to time the same thing with some simple algorithm, like XOR over the whole 8k page, for comparison. -- Hannu Krosing <[EMAIL PROTECTED]> ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly