Received: from malur.postgresql.org ([217.196.149.56])
	by arkaria.postgresql.org with esmtps
 (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)
	(Exim 4.92)
	(envelope-from <pgsql-performance-owner+archive@lists.postgresql.org>)
	id 1lKndo-0006iI-H8
	for pgsql-performance@arkaria.postgresql.org; Fri, 12 Mar 2021 19:40:08 +0000
Received: from localhost ([127.0.0.1] helo=malur.postgresql.org)
	by malur.postgresql.org with esmtp (Exim 4.92)
	(envelope-from <pgsql-performance-owner+archive@lists.postgresql.org>)
	id 1lKndn-0006WO-Dd
	for pgsql-performance@arkaria.postgresql.org; Fri, 12 Mar 2021 19:40:07 +0000
Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29])
	by malur.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)
	(Exim 4.92)
	(envelope-from <bruce@momjian.us>)
	id 1lKndn-0006WG-6A
	for pgsql-performance@lists.postgresql.org; Fri, 12 Mar 2021 19:40:07 +0000
Received: from momjian.us ([72.94.173.45])
	by magus.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)
	(Exim 4.92)
	(envelope-from <bruce@momjian.us>)
	id 1lKndg-0006Ke-FI
	for pgsql-performance@postgresql.org; Fri, 12 Mar 2021 19:40:06 +0000
Received: from bruce by momjian.us with local (Exim 4.92)
	(envelope-from <bruce@momjian.us>)
	id 1lKnde-0001kT-N9; Fri, 12 Mar 2021 14:39:58 -0500
Date: Fri, 12 Mar 2021 14:39:58 -0500
From: Bruce Momjian <bruce@momjian.us>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Luca Ferrari <fluca1978@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: FreeBSD UFS & fsync
Message-ID: <20210312193958.GA5362@momjian.us>
References: 
 <CAKoxK+5mb7X6+ojzufJQb_s-way4ntjtOG+bbMtifGrccirYGg@mail.gmail.com>
 <CA+hUKG+0DWFSZTGmezxZttXTy0YYrX=oemxiw8Gzz3hSTU64Jw@mail.gmail.com>
 <CAKoxK+7PgBe=38ZBJk3z7Qp7erMV9cG7Rx10uUPAorjpC+aVhA@mail.gmail.com>
 <CAKoxK+7sjq-WhedUFfaBT8svW+-F4tb11fM1xsWo+7LvusRhwg@mail.gmail.com>
 <20210311142945.GB2469@momjian.us>
 <CAKoxK+6ueNbgSR80At9RsZ7C1fYx3TjB9GhjAWT1q=TUzC1VuA@mail.gmail.com>
 <CA+hUKG+18FSyKWx5FOSHzOjgLvp+btNGTFaj14eDJ7-W8JHtTw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: 
 <CA+hUKG+18FSyKWx5FOSHzOjgLvp+btNGTFaj14eDJ7-W8JHtTw@mail.gmail.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
List-Id: <pgsql-performance.lists.postgresql.org>
List-Help: <https://lists.postgresql.org/manage/>
List-Subscribe: <https://lists.postgresql.org/manage/>
List-Post: <mailto:pgsql-performance@lists.postgresql.org>
List-Owner: <mailto:pgsql-performance-owner@lists.postgresql.org>
List-Archive: <https://www.postgresql.org/list/pgsql-performance>
Archived-At: 
 <https://www.postgresql.org/message-id/20210312193958.GA5362%40momjian.us>
Precedence: bulk

On Fri, Mar 12, 2021 at 10:33:29PM +1300, Thomas Munro wrote:
> On Fri, Mar 12, 2021 at 10:09 PM Luca Ferrari <fluca1978@gmail.com> wrote:
> >        fdatasync                         16269.365 ops/sec      61 usecs/op
> >        fsync                              8471.429 ops/sec     118 usecs/op
> 
> > Non-sync'ed 8kB writes:
> >        write                            278484.510 ops/sec       4 usecs/op
> 
> > tps = 136.963971 (excluding connections establishing)
> 
> It looks like your system is performing very badly for some other
> reason, so that synchronous I/O waits are only a small proportion of
> the time, and thus fsync=off doesn't speed things up very much.  I'd
> look into profiling the system to try to figure out what it's doing...
> maybe it's suffering from super slow hypercalls for gettimeofday(), or
> something like that?

And we have pg_test_timing for gettimeofday() testing.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee