From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Alexander Korotkov <a.korotkov@postgrespro.ru>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Should we cacheline align PGXACT?
In-reply-to: <7503E425-6651-4D40-83FD-592AF580D618@gmail.com>
References: 
 <CAPpHfdtJY4zOEDsjad6J5AyZMqZcv6gSY9AkKpA7qN3jyQ2+1Q@mail.gmail.com>
 <7503E425-6651-4D40-83FD-592AF580D618@gmail.com>
Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Sat, 20 Aug 2016 14:33:13 -0400"
Date: Sat, 20 Aug 2016 14:38:52 -0400
Message-ID: <29160.1471718332@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

Robert Haas <robertmhaas@gmail.com> writes:
> Wow, nice results.  My intuition on why PGXACT helped in the first place was that it minimized the number of cache lines that had to be touched to take a snapshot. Padding obviously would somewhat increase that again, so I can't quite understand why it seems to be helping... any idea?

That's an interesting point.  I wonder whether this whole thing will be
useless or even counterproductive after (if) Heikki's CSN-snapshot patch
gets in.  I would certainly not mind reverting the PGXACT/PGPROC
separation if it proves no longer helpful after that.

			regards, tom lane


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers