From owner-freebsd-net@FreeBSD.ORG  Mon Apr  8 17:30:13 2013
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115])
 by hub.freebsd.org (Postfix) with ESMTP id C78D28A1
 for <freebsd-net@freebsd.org>; Mon,  8 Apr 2013 17:30:13 +0000 (UTC)
 (envelope-from VenkatKumar.Duvvuru@Emulex.Com)
Received: from CMEXEDGE1.ext.emulex.com (cmexedge1.ext.emulex.com
 [138.239.224.99]) by mx1.freebsd.org (Postfix) with ESMTP id 914F2CD0
 for <freebsd-net@freebsd.org>; Mon,  8 Apr 2013 17:30:13 +0000 (UTC)
Received: from CMEXHTCAS2.ad.emulex.com (138.239.115.218) by
 CMEXEDGE1.ext.emulex.com (138.239.224.99) with Microsoft SMTP Server (TLS) id
 14.2.318.4; Mon, 8 Apr 2013 10:15:36 -0700
Received: from CMEXMB1.ad.emulex.com ([169.254.1.136]) by
 CMEXHTCAS2.ad.emulex.com ([2002:8aef:71b8::8aef:71b8]) with mapi id
 14.02.0318.004; Mon, 8 Apr 2013 10:14:58 -0700
From: "Duvvuru,Venkat Kumar" <VenkatKumar.Duvvuru@Emulex.Com>
To: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
Subject: drbr_enqueue - OCE driver - Freebsd 9.1
Thread-Topic: drbr_enqueue - OCE driver - Freebsd 9.1
Thread-Index: Ac40fItUT8/z+mHWRfWrn38wP/SoOw==
Date: Mon, 8 Apr 2013 17:14:59 +0000
Message-ID: <BF3270C86E8B1349A26C34E4EC1C44CB2B82015D@CMEXMB1.ad.emulex.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach: 
X-MS-TNEF-Correlator: 
x-originating-ip: [10.226.252.152]
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
X-Content-Filtered-By: Mailman/MimeDel 2.1.14
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 08 Apr 2013 17:30:13 -0000

Hi,
In the transmit path, if enqueue mechanism is used instead of blocking on t=
he lock, the throughput is not good in some scenarios (especially single qu=
eue, multiple connections).
For example:
if (TRY_LOCK(&wq->tx_lock)) {
           status =3D oce_multiq_transmit(ifp, m, wq);
           UNLOCK(&wq->tx_lock);
     } else {
           status =3D drbr_enqueue(ifp, wq->br, m);
     }

Instead of the above code where the request is enqueued if I use a normal L=
OCK and block on it, it is giving good performance.

Any suggestions on why the throughput is low in case of enqueue mechanism.

Thx,
Venkat.