From owner-freebsd-fs@FreeBSD.ORG  Sun Oct  2 22:33:32 2011
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: freebsd-fs@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 30DEA106564A
	for <freebsd-fs@freebsd.org>; Sun,  2 Oct 2011 22:33:32 +0000 (UTC)
	(envelope-from freebsd-fs@m.gmane.org)
Received: from lo.gmane.org (lo.gmane.org [80.91.229.12])
	by mx1.freebsd.org (Postfix) with ESMTP id AFC9E8FC0C
	for <freebsd-fs@freebsd.org>; Sun,  2 Oct 2011 22:33:31 +0000 (UTC)
Received: from list by lo.gmane.org with local (Exim 4.69)
	(envelope-from <freebsd-fs@m.gmane.org>) id 1RAUbC-0004z2-HU
	for freebsd-fs@freebsd.org; Mon, 03 Oct 2011 00:33:30 +0200
Received: from 15-91.dsl.iskon.hr ([89.164.15.91])
	by main.gmane.org with esmtp (Gmexim 0.1 (Debian))
	id 1AlnuQ-0007hv-00
	for <freebsd-fs@freebsd.org>; Mon, 03 Oct 2011 00:33:30 +0200
Received: from ivoras by 15-91.dsl.iskon.hr with local (Gmexim 0.1 (Debian))
	id 1AlnuQ-0007hv-00
	for <freebsd-fs@freebsd.org>; Mon, 03 Oct 2011 00:33:30 +0200
X-Injected-Via-Gmane: http://gmane.org/
To: freebsd-fs@freebsd.org
From: Ivan Voras <ivoras@freebsd.org>
Date: Mon, 03 Oct 2011 00:33:15 +0200
Lines: 33
Message-ID: <j6aorc$hf0$1@dough.gmane.org>
References: <CAOfDtXMm9K_fbOmvG2gvXxDfKakkgpPt9MLifqDxa4wCibMExg@mail.gmail.com>
	<alpine.GSO.1.10.1110011122030.882@multics.mit.edu>
	<CADLo83-s_3H8PbbxOPPxbe0m10U0U5JW-feB294dFs+Q3iTWvg@mail.gmail.com>
	<CAGMYy3ssi+kAuufDTHA1z6u7jRrZwRRkCCkcO94GHNGF9Rku_w@mail.gmail.com>
	<20111002020231.GA70864@icarus.home.lan>
	<CAGMYy3sCCxOiVqeP4PVbvxnpcyoyQZoL+w3nY8STYnpUNfj6JQ@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
X-Complaints-To: usenet@dough.gmane.org
X-Gmane-NNTP-Posting-Host: 15-91.dsl.iskon.hr
User-Agent: Mozilla/5.0 (Windows NT 6.1;
	rv:7.0.1) Gecko/20110929 Thunderbird/7.0.1
In-Reply-To: <CAGMYy3sCCxOiVqeP4PVbvxnpcyoyQZoL+w3nY8STYnpUNfj6JQ@mail.gmail.com>
Subject: Re: is TMPFS still highly experimental?
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 02 Oct 2011 22:33:32 -0000

On 02/10/2011 07:27, Xin LI wrote:

> The problem Ivan have asserted was not confirmed by anyone who have
> swap configured properly.  Gleb have pointed out that it might be
> related to a series of integer overflow by the way (he have also fixed
> a lot of tmpfs issues by the way).

Well, instead of guessing I can point you to the way I got the original
situation - you said you have ZFS configured so it would be easy for you
to check.

You should to something like this:

	- configure your system to the best of your abilities (but post what
you did different from the defaults)
	- install postgresql (8.4+, but I don't think the version is
important), configure it so it gets half the system memory or 2/3 the
system memory for its shared_buffers.
	- install pgbench
	- initialize pgbench so that the database definitely is larger than the
entire memory you got (NOTE: THIS IS NOT A CONTRIVED TEST - lots of
databases in practice are larger than the RAM in the server).
	- run pgbench & observe the results.

This should create really bad contention problem for memory between
postgresql and ZFS, which should manifest itself in tmpfs shrinking to 0
bytes free.

If you don't get this problem then great, it might be solved!


(for more info on pgbench, see this:
http://www.westnet.com/~gsmith/content/postgresql/pgbench-scaling.htm).