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 2EE1923D for ; Tue, 6 Mar 2018 09:57:12 +0100 (CET) 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 B83054023150; Tue, 6 Mar 2018 08:57:11 +0000 (UTC) Received: from [10.36.112.61] (ovpn-112-61.ams2.redhat.com [10.36.112.61]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B016E10FFE6D; Tue, 6 Mar 2018 08:57:09 +0000 (UTC) To: Junjie Chen , yliu@fridaylinux.org, jianfeng.tan@intel.com Cc: dev@dpdk.org References: <1519483453-12613-1-git-send-email-junjie.j.chen@intel.com> <1519723268-28723-1-git-send-email-junjie.j.chen@intel.com> From: Maxime Coquelin Message-ID: <156edfa4-da00-70c8-f3e8-a034f1db5ae2@redhat.com> Date: Tue, 6 Mar 2018 09:57:07 +0100 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: <1519723268-28723-1-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 [10.11.55.6]); Tue, 06 Mar 2018 08:57:11 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Tue, 06 Mar 2018 08:57:11 +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 v2] 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: Tue, 06 Mar 2018 08:57:12 -0000 On 02/27/2018 10:21 AM, Junjie Chen wrote: > In vhost-switch example, when binding nic to vfio-pci, 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 > --- > Changes in V2: > - add doc in vhost lib > > doc/guides/prog_guide/vhost_lib.rst | 3 +++ > doc/guides/sample_app_ug/vhost.rst | 5 ++++- > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst > index 18227b6..bdf77d6 100644 > --- a/doc/guides/prog_guide/vhost_lib.rst > +++ b/doc/guides/prog_guide/vhost_lib.rst > @@ -83,6 +83,9 @@ 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 does not work when using vfio-pci driver currently, this is > + because we don't setup iommu dma mapping for guest memory. > + I guess that it should work with vfio-pci in noiommu mode? Maybe worth to clarify. > - ``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..840c1fd 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 vfio-pci driver, 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 >