From owner-freebsd-current@FreeBSD.ORG  Mon Mar 22 08:23:46 2010
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 351A01065673;
	Mon, 22 Mar 2010 08:23:46 +0000 (UTC)
	(envelope-from phk@critter.freebsd.dk)
Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222])
	by mx1.freebsd.org (Postfix) with ESMTP id E88F98FC1A;
	Mon, 22 Mar 2010 08:23:45 +0000 (UTC)
Received: from critter.freebsd.dk (critter.freebsd.dk [192.168.61.3])
	by phk.freebsd.dk (Postfix) with ESMTP id 27AF56435;
	Mon, 22 Mar 2010 08:23:44 +0000 (UTC)
Received: from critter.freebsd.dk (localhost [127.0.0.1])
	by critter.freebsd.dk (8.14.3/8.14.3) with ESMTP id o2M8NhGQ005755;
	Mon, 22 Mar 2010 08:23:43 GMT (envelope-from phk@critter.freebsd.dk)
To: Andriy Gapon <avg@icyb.net.ua>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Sun, 21 Mar 2010 16:56:32 +0200."
	<4BA633A0.2090108@icyb.net.ua> 
Date: Mon, 22 Mar 2010 08:23:43 +0000
Message-ID: <5754.1269246223@critter.freebsd.dk>
Sender: phk@critter.freebsd.dk
Cc: Alexander Motin <mav@FreeBSD.org>, freebsd-current@FreeBSD.org,
	Ivan Voras <ivoras@FreeBSD.org>, freebsd-arch@FreeBSD.org
Subject: Re: Increasing MAXPHYS 
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 22 Mar 2010 08:23:46 -0000

In message <4BA633A0.2090108@icyb.net.ua>, Andriy Gapon writes:
>on 21/03/2010 16:05 Alexander Motin said the following:
>> Ivan Voras wrote:
>>> Hmm, it looks like it could be easy to spawn more g_* threads (and,
>>> barring specific class behaviour, it has a fair chance of working out of
>>> the box) but the incoming queue will need to also be broken up for
>>> greater effect.
>> 
>> According to "notes", looks there is a good chance to obtain races, as
>> some places expect only one up and one down thread.
>
>I haven't given any deep thought to this issue, but I remember us discussing
>them over beer :-)

The easiest way to obtain more parallelism, is to divide the mesh into
multiple independent meshes.

This will do you no good if you have five disks in a RAID-5 config, but
if you have two disks each mounted on its own filesystem, you can run
a g_up & g_down for each of them.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.