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From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: "Chen, Junjie J" <junjie.j.chen@intel.com>,
	"yliu@fridaylinux.org" <yliu@fridaylinux.org>,
	"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] doc: add driver limitation for vhost dequeue zero copy
Date: Mon, 26 Feb 2018 04:44:07 +0000	[thread overview]
Message-ID: <ED26CBA2FAD1BF48A8719AEF02201E36514508B4@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <1519483453-12613-1-git-send-email-junjie.j.chen@intel.com>

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
> 
> 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?

> 
> Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
> ---
>  doc/guides/sample_app_ug/vhost.rst | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> 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/guides/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.
> 
>  **--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
> --
> 2.0.1

next prev parent reply	other threads:[~2018-02-26  4:44 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-24 14:44 Junjie Chen
2018-02-26  4:44 ` Tan, Jianfeng [this message]
2018-03-13  9:12   ` Kovacevic, Marko
2018-03-13  9:18     ` Chen, Junjie J
2018-02-27  9:21 ` [dpdk-dev] [PATCH v2] " Junjie Chen
2018-03-06  8:57   ` Maxime Coquelin
2018-03-09  5:17     ` Chen, Junjie J
2018-03-09 10:07   ` [dpdk-dev] [PATCH v3] " Junjie Chen
2018-03-12  3:15     ` Tan, Jianfeng
2018-03-13  9:19       ` Chen, Junjie J
2018-03-14 16:24     ` [dpdk-dev] [PATCH v4] " Junjie Chen
2018-03-19  6:56       ` Tan, Jianfeng
2018-03-29 12:14       ` Maxime Coquelin
2018-04-11 14:34         ` Maxime Coquelin

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