From owner-freebsd-current@FreeBSD.ORG  Mon Jan  7 10:38:07 2013
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115])
 by hub.freebsd.org (Postfix) with ESMTP id 16943658
 for <freebsd-current@freebsd.org>; Mon,  7 Jan 2013 10:38:07 +0000 (UTC)
 (envelope-from daniel@digsys.bg)
Received: from smtp-sofia.digsys.bg (smtp-sofia.digsys.bg [193.68.3.230])
 by mx1.freebsd.org (Postfix) with ESMTP id 73263C1A
 for <freebsd-current@freebsd.org>; Mon,  7 Jan 2013 10:38:05 +0000 (UTC)
Received: from [192.92.129.185] ([192.92.129.185]) (authenticated bits=0)
 by smtp-sofia.digsys.bg (8.14.5/8.14.5) with ESMTP id r07AFIR7072459
 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO);
 Mon, 7 Jan 2013 12:15:19 +0200 (EET) (envelope-from daniel@digsys.bg)
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\))
Subject: Re: ZFS/RAIDZ and SAMBA: abyssimal performance
From: Daniel Kalchev <daniel@digsys.bg>
In-Reply-To: <1ADC2ECB-70FF-4DDD-9D62-16E2EEECDD8B@my.gd>
Date: Mon, 7 Jan 2013 12:14:51 +0200
Content-Transfer-Encoding: quoted-printable
Message-Id: <A73352A5-12BE-4EC8-A5BC-C1D7C13E0A24@digsys.bg>
References: <50E6DE91.7010404@zedat.fu-berlin.de>
 <1ADC2ECB-70FF-4DDD-9D62-16E2EEECDD8B@my.gd>
To: Fleuriot Damien <ml@my.gd>
X-Mailer: Apple Mail (2.1499)
Cc: Current FreeBSD <freebsd-current@freebsd.org>,
 "O. Hartmann" <ohartman@zedat.fu-berlin.de>
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
 <freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/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, 07 Jan 2013 10:38:07 -0000


On Jan 4, 2013, at 4:06 PM, Fleuriot Damien <ml@my.gd> wrote:

>=20
> And network cards:
> # Up a bit our intel cards parameters
> hw.em.txd=3D4096
> hw.em.rxd=3D4096
> hw.em.tx_int_delay=3D512
> hw.em.rx_int_delay=3D512
> hw.em.tx_abs_int_delay=3D1024
> hw.em.rx_abs_int_delay=3D1024
>=20

I am curious why we need to manually set up these values. Especially the =
txd/rxd -- here are few controllers supported by the em driver that =
can't handle 4096 descriptors and the choice could really be made at =
driver attach time.. That could also permit different em interfaces in =
the system (using different chips) to have different settings.

My belief is the auto tuning should set things up for maximum =
performance, given the hardware and if someone really needs smaller =
queues they could just use the tunables.=20

Are there drawbacks?

Daniel=