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 22AE21BB9F for ; Wed, 11 Apr 2018 16:34:52 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6C16484250; Wed, 11 Apr 2018 14:34:51 +0000 (UTC) Received: from [10.36.112.36] (ovpn-112-36.ams2.redhat.com [10.36.112.36]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CCB93215CDAF; Wed, 11 Apr 2018 14:34:49 +0000 (UTC) From: Maxime Coquelin 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> <20e69848-eedf-9e53-55eb-d5be1366a629@redhat.com> Message-ID: <038762e8-ca3d-fd1e-b531-5761059f8cc3@redhat.com> Date: Wed, 11 Apr 2018 16:34:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20e69848-eedf-9e53-55eb-d5be1366a629@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 11 Apr 2018 14:34:51 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 11 Apr 2018 14:34:51 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.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: Wed, 11 Apr 2018 14:34:52 -0000 On 03/29/2018 02:14 PM, Maxime Coquelin wrote: > > > 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? Applied to dpdk-next-virtio/master Thanks, Maxime > 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 >>