From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by dpdk.org (Postfix) with ESMTP id A7BE94CAB for ; Mon, 26 Feb 2018 05:44:15 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Feb 2018 20:44:11 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,396,1515484800"; d="scan'208";a="37421184" Received: from fmsmsx104.amr.corp.intel.com ([10.18.124.202]) by orsmga002.jf.intel.com with ESMTP; 25 Feb 2018 20:44:11 -0800 Received: from fmsmsx154.amr.corp.intel.com (10.18.116.70) by fmsmsx104.amr.corp.intel.com (10.18.124.202) with Microsoft SMTP Server (TLS) id 14.3.319.2; Sun, 25 Feb 2018 20:44:11 -0800 Received: from shsmsx151.ccr.corp.intel.com (10.239.6.50) by FMSMSX154.amr.corp.intel.com (10.18.116.70) with Microsoft SMTP Server (TLS) id 14.3.319.2; Sun, 25 Feb 2018 20:44:10 -0800 Received: from shsmsx103.ccr.corp.intel.com ([169.254.4.116]) by SHSMSX151.ccr.corp.intel.com ([169.254.3.116]) with mapi id 14.03.0319.002; Mon, 26 Feb 2018 12:44:09 +0800 From: "Tan, Jianfeng" To: "Chen, Junjie J" , "yliu@fridaylinux.org" , "maxime.coquelin@redhat.com" CC: "dev@dpdk.org" Thread-Topic: [PATCH] doc: add driver limitation for vhost dequeue zero copy Thread-Index: AQHTrT3mNlznCdVwVUaiwcs8XsLhwqO2HLYA Date: Mon, 26 Feb 2018 04:44:07 +0000 Message-ID: References: <1519483453-12613-1-git-send-email-junjie.j.chen@intel.com> In-Reply-To: <1519483453-12613-1-git-send-email-junjie.j.chen@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH] 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: Mon, 26 Feb 2018 04:44:16 -0000 Hi Junjie, > -----Original Message----- > From: Chen, Junjie J > Sent: Saturday, February 24, 2018 10:44 PM > To: yliu@fridaylinux.org; maxime.coquelin@redhat.com; Tan, Jianfeng > Cc: dev@dpdk.org; Chen, Junjie J > Subject: [PATCH] doc: add driver limitation for vhost dequeue zero copy >=20 > 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. IMO, it's a limitation that can be fixed. Do you want to try fixing it? >=20 > Signed-off-by: Junjie Chen > --- > doc/guides/sample_app_ug/vhost.rst | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) >=20 > diff --git a/doc/guides/sample_app_ug/vhost.rst > b/doc/guides/sample_app_ug/vhost.rst > index a4bdc6a..1591a31 100644 > --- a/doc/guides/sample_app_ug/vhost.rst > +++ b/doc/guides/sample_app_ug/vhost.rst Besides, we might also need to put such limitation at http://dpdk.org/doc/g= uides/prog_guide/vhost_lib.html Thanks, Jianfeng > @@ -147,7 +147,10 @@ retries on an RX burst, it takes effect only when rx > retry is enabled. The > default value is 15. >=20 > **--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=3D0) due to currently we don't setup iommu dma > mapping for > +guest memory. >=20 > **--vlan-strip 0|1** > VLAN strip option is removed, because different NICs have different > behaviors > -- > 2.0.1