Date: Fri, 9 Apr 2021 15:36:58 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>,
	Stephen Frost <sfrost@snowman.net>,
	Andres Freund <andres@anarazel.de>,
	Jakub Wartak <Jakub.Wartak@tomtom.com>,
	Alvaro Herrera <alvherre@2ndquadrant.com>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Dmitry Dolgov <9erthalion6@gmail.com>,
	David Steele <david@pgmasters.net>, pgsql-hackers@postgresql.org
Subject: Re: WIP: WAL prefetch (another approach)
Message-ID: <20210409203658.GU6592@telsasoft.com>
References: <20210214231815.GO27507@tamriel.snowman.net>
 <17b3f450-048c-f3a6-7086-259523f33cbc@enterprisedb.com>
 <20210317214331.GF20766@tamriel.snowman.net>
 <28c3352e-5388-6410-aae7-05907079e6c9@enterprisedb.com>
 <CA+hUKGLHTjbBPFX6E1ZCGVyQD30-vWtH=N6EcHEzW13q+jh7FQ@mail.gmail.com>
 <8dd2dcc2-0b6b-a4ab-c1b3-032c0a5ab1c3@enterprisedb.com>
 <CA+hUKGKmkKfH1h9XG5ctYCgqeOHGdN5bHMoQMZLR=+kLY0PQzA@mail.gmail.com>
 <CA+hUKGLsF8sEE+n3qoaV6+XjmYEwYoFVDbLPbYTGz7oGkL=iZA@mail.gmail.com>
 <20210409033703.GP6592@telsasoft.com>
 <CA+hUKG+deAXJUigdX4yDqwzWyqr6qLA8StiWJVFOHTy83eqqtA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: 
 <CA+hUKG+deAXJUigdX4yDqwzWyqr6qLA8StiWJVFOHTy83eqqtA@mail.gmail.com>
User-Agent: Mutt/1.9.4 (2018-02-28)
Archived-At: 
 <https://www.postgresql.org/message-id/20210409203658.GU6592%40telsasoft.com>
Precedence: bulk

On Sat, Apr 10, 2021 at 08:27:42AM +1200, Thomas Munro wrote:
> On Fri, Apr 9, 2021 at 3:37 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> > Here's some little language fixes.
> 
> Thanks!  Done.  I rewrote the gibberish comment that made you say
> "XXX: what?".  Pushed.
> 
> > BTW, before beginning "recovery", PG syncs all the data dirs.
> > This can be slow, and it seems like the slowness is frequently due to file
> > metadata.  For example, that's an obvious consequence of an OS crash, after
> > which the page cache is empty.  I've made a habit of running find /zfs -ls |wc
> > to pre-warm it, which can take a little bit, but then the recovery process
> > starts moments later.  I don't have any timing measurements, but I expect that
> > starting to stat() all data files as soon as possible would be a win.
> 
> Did you see commit 61752afb, "Provide
> recovery_init_sync_method=syncfs"?  Actually I believe it's safe to
> skip that phase completely and do a tiny bit more work during
> recovery, which I'd like to work on for v15[1].

Yes, I have it in my list for v14 deployment.  Thanks for that.

Did you see this?
https://www.postgresql.org/message-id/GV0P278MB0483490FEAC879DCA5ED583DD2739%40GV0P278MB0483.CHEP278.PROD.OUTLOOK.COM

I meant to mail you so you could include it in the same commit, but forgot
until now.

-- 
Justin