From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by dpdk.org (Postfix) with ESMTP id 372C02C5E for ; Thu, 29 Mar 2018 14:14:58 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A13728182D01; Thu, 29 Mar 2018 12:14:57 +0000 (UTC) Received: from [10.36.112.54] (ovpn-112-54.ams2.redhat.com [10.36.112.54]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7E0C710B00A2; Thu, 29 Mar 2018 12:14:56 +0000 (UTC) To: Junjie Chen , jianfeng.tan@intel.com, yliu@fridaylinux.org, "Mcnamara, John" Cc: dev@dpdk.org References: <1520590048-151284-1-git-send-email-junjie.j.chen@intel.com> <1521044656-105962-1-git-send-email-junjie.j.chen@intel.com> From: Maxime Coquelin Message-ID: <20e69848-eedf-9e53-55eb-d5be1366a629@redhat.com> Date: Thu, 29 Mar 2018 14:14:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <1521044656-105962-1-git-send-email-junjie.j.chen@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Thu, 29 Mar 2018 12:14:57 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Thu, 29 Mar 2018 12:14:57 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'maxime.coquelin@redhat.com' RCPT:'' Subject: Re: [dpdk-dev] [PATCH v4] doc: add driver limitation for vhost dequeue zero copy X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Mar 2018 12:14:58 -0000 On 03/14/2018 05:24 PM, Junjie Chen wrote: > In vhost-switch example, when binding nic to vfio-pci with iommu enabled, > dequeue zero copy cannot work in VM2NIC mode due to no iommu dma mapping > is setup for guest memory currently. > > Signed-off-by: Junjie Chen Reviewed-by: Maxime Coquelin John, as this is a doc patch for Vhost, does it go through the doc tree or through Virtio one? Thanks, Maxime > --- > Changes in V4: > - make words more accurate > Changes in V3: > - update limitation to iommu > Changes in V2: > - add doc in vhost lib > doc/guides/prog_guide/vhost_lib.rst | 5 +++++ > doc/guides/sample_app_ug/vhost.rst | 5 ++++- > 2 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst > index 18227b6..b49e36e 100644 > --- a/doc/guides/prog_guide/vhost_lib.rst > +++ b/doc/guides/prog_guide/vhost_lib.rst > @@ -83,6 +83,11 @@ The following is an overview of some key Vhost API functions: > of those segments, thus the fewer the segments, the quicker we will get > the mapping. NOTE: we may speed it by using tree searching in future. > > + * zero copy can not work when using vfio-pci with iommu mode currently, this > + is because we don't setup iommu dma mapping for guest memory. If you have > + to use vfio-pci driver, please insert vfio-pci kernel module in noiommu > + mode. > + > - ``RTE_VHOST_USER_IOMMU_SUPPORT`` > > IOMMU support will be enabled when this flag is set. It is disabled by > diff --git a/doc/guides/sample_app_ug/vhost.rst b/doc/guides/sample_app_ug/vhost.rst > index a4bdc6a..f0bb169 100644 > --- a/doc/guides/sample_app_ug/vhost.rst > +++ b/doc/guides/sample_app_ug/vhost.rst > @@ -147,7 +147,10 @@ retries on an RX burst, it takes effect only when rx retry is enabled. The > default value is 15. > > **--dequeue-zero-copy** > -Dequeue zero copy will be enabled when this option is given. > +Dequeue zero copy will be enabled when this option is given. it is worth to > +note that if NIC is binded to driver with iommu enabled, dequeue zero copy > +cannot work at VM2NIC mode (vm2vm=0) due to currently we don't setup iommu > +dma mapping for guest memory. > > **--vlan-strip 0|1** > VLAN strip option is removed, because different NICs have different behaviors >