From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <mst@redhat.com>
Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28])
 by dpdk.org (Postfix) with ESMTP id 3CE528DA4
 for <dev@dpdk.org>; Thu,  1 Oct 2015 11:42:09 +0200 (CEST)
Received: from int-mx14.intmail.prod.int.phx2.redhat.com
 (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27])
 by mx1.redhat.com (Postfix) with ESMTPS id 7888C461F0;
 Thu,  1 Oct 2015 09:42:08 +0000 (UTC)
Received: from redhat.com (ovpn-116-83.ams2.redhat.com [10.36.116.83])
 by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id
 t919g4lZ018795; Thu, 1 Oct 2015 05:42:06 -0400
Date: Thu, 1 Oct 2015 12:42:04 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Avi Kivity <avi@scylladb.com>
Message-ID: <20151001123335-mutt-send-email-mst@redhat.com>
References: <560BDE24.8000308@scylladb.com>
 <20150930165359-mutt-send-email-mst@redhat.com>
 <560BF782.4070308@scylladb.com>
 <20150930175848-mutt-send-email-mst@redhat.com>
 <560C0171.7080507@scylladb.com> <20150930204016.GA29975@redhat.com>
 <20151001113828-mutt-send-email-mst@redhat.com>
 <560CF44A.60102@scylladb.com>
 <20151001120027-mutt-send-email-mst@redhat.com>
 <560CFB66.5050904@scylladb.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <560CFB66.5050904@scylladb.com>
X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] Having troubles binding an SR-IOV VF to
 uio_pci_generic on Amazon instance
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
X-List-Received-Date: Thu, 01 Oct 2015 09:42:09 -0000

On Thu, Oct 01, 2015 at 12:22:46PM +0300, Avi Kivity wrote:
> even when they are some users
> prefer to avoid the performance penalty.

I don't think there's a measureable penalty from passing through the
IOMMU, as long as mappings are mostly static (i.e. iommu=pt).  I sure
never saw any numbers that show such.

-- 
MST