[email protected] wrote on 04/03/2017 01:58:03 PM: > From: Andres Freund <[email protected]> > To: Alexander Korotkov <[email protected]> > Cc: David Steele <[email protected]>, Ashutosh Sharma > <[email protected]>, Simon Riggs <[email protected]>, Alvaro > Herrera <[email protected]>, Robert Haas > <[email protected]>, Bernd Helmle <[email protected]>, Tomas > Vondra <[email protected]>, pgsql-hackers <pgsql- > [email protected]> > Date: 04/03/2017 01:59 PM > Subject: Re: [HACKERS] Should we cacheline align PGXACT? > Sent by: [email protected] > > On 2017-03-25 19:35:35 +0300, Alexander Korotkov wrote: > > On Wed, Mar 22, 2017 at 12:23 AM, David Steele <[email protected]> wrote: > > > > > Hi Alexander > > > > > > On 3/10/17 8:08 AM, Alexander Korotkov wrote: > > > > > > Results look good for me. Idea of committing both of patches looks > > >> attractive. > > >> We have pretty much acceleration for read-only case and small > > >> acceleration for read-write case. > > >> I'll run benchmark on 72-cores machine as well. > > >> > > > > > > Have you had a chance to run those tests yet? > > > > > > > I discovered an interesting issue. > > I found that ccce90b3 (which was reverted) gives almost same effect as > > PGXACT alignment on read-only test on 72-cores machine. > > That's possibly because it changes alignment? > > > > That shouldn't be related to the functionality of ccce90b3 itself, because > > read-only test don't do anything with clog. And that appears to be true. > > Padding of PGPROC gives same positive effect as ccce90b3. Padding patch > > (pgproc-pad.patch) is attached. It's curious that padding changes size of > > PGPROC from 816 bytes to 848 bytes. So, size of PGPROC remains 16-byte > > aligned. So, probably effect is related to distance between PGPROC > > members... > > > > See comparison of 16-bytes alignment of PGXACT + reduce PGXACT access vs. > > padding of PGPROC. > > My earlier testing had showed that padding everything is the best > approach :/ > My approach has been to, generally, pad "everything" as well. In my testing on power, I padded PGXACT to 16 bytes. To my surprise, with the padding in isolation, the performance (on hammerdb) was slightly degraded.
Jim Van Fleet > > I'm inclined to push this to the next CF, it seems we need a lot more > benchmarking here. > > Greetings, > > Andres Freund > > > -- > Sent via pgsql-hackers mailing list ([email protected]) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers >
