From owner-freebsd-performance@FreeBSD.ORG  Wed Aug 24 21:00:40 2005
Return-Path: <owner-freebsd-performance@FreeBSD.ORG>
X-Original-To: freebsd-performance@freebsd.org
Delivered-To: freebsd-performance@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 1D75E16A41F
	for <freebsd-performance@freebsd.org>;
	Wed, 24 Aug 2005 21:00:40 +0000 (GMT)
	(envelope-from jarek@adeon.lublin.pl)
Received: from v00061.home.net.pl (list.pl [212.85.96.61])
	by mx1.FreeBSD.org (Postfix) with SMTP id 399D343D45
	for <freebsd-performance@freebsd.org>;
	Wed, 24 Aug 2005 21:00:36 +0000 (GMT)
	(envelope-from jarek@adeon.lublin.pl)
Received: from bib251.neoplus.adsl.tpnet.pl (jarek.list@home@83.28.117.251)
	by matrix01.home.net.pl with SMTP; Wed, 24 Aug 2005 21:00:32 -0000
Date: Wed, 24 Aug 2005 23:00:23 +0200
From: JG <jarek@adeon.lublin.pl>
X-Mailer: The Bat! (v3.0) Professional
X-Priority: 3 (Normal)
Message-ID: <1626642863.20050824230023@adeon.lublin.pl>
To: Jonathan Noack <noackjr@alumni.rice.edu>
In-Reply-To: <430CBC18.6040902@alumni.rice.edu>
References: <1168719770.20050824183357@adeon.lublin.pl>
	<430CBC18.6040902@alumni.rice.edu>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Cc: freebsd-performance@freebsd.org
Subject: Re[2]: slow tar performance on fbsd5
X-BeenThere: freebsd-performance@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: JG <jarek@adeon.lublin.pl>
List-Id: Performance/tuning <freebsd-performance.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-performance>,
	<mailto:freebsd-performance-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-performance>
List-Post: <mailto:freebsd-performance@freebsd.org>
List-Help: <mailto:freebsd-performance-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-performance>,
	<mailto:freebsd-performance-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 24 Aug 2005 21:00:40 -0000

> Will noatime make a difference when unpacking a tar archive (assuming an
> otherwise idle system, at least)?  My understanding of atime is that it
> might slow down the disk for later accesses due to atime writes, but
> when creating files it shouldn't have any effect.  Is that not correct?

Yes, you're right.

> Your other settings appear ok, but I'd turn off hyperthreading.  Almost
> every FreeBSD/HT test has shown that it reduces performance because the
> scheduler is not HT-aware.  When the system is relatively idle (single
> dd running, for example), it might not pessimize things, but it will
> most likely slow you down under load.

HTT is a big performance hit for me, mainly for webserver. I've much worse diskinfo
results without HTT, don't know why. Tar is upacking a bit longer with HTT disabled.

> This sounds like you're running into the old "lemming syncer" problem.
> There is currently some work on disk schedulers (even a Summer of Code
> project), but it will most likely not make it into 5.x.

Agrh..

Regards,
Jarek