From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: "Chen, Junjie J" <junjie.j.chen@intel.com>,
"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
"yliu@fridaylinux.org" <yliu@fridaylinux.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v4] doc: add driver limitation for vhost dequeue zero copy
Date: Mon, 19 Mar 2018 06:56:51 +0000 [thread overview]
Message-ID: <ED26CBA2FAD1BF48A8719AEF02201E3651493A08@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <1521044656-105962-1-git-send-email-junjie.j.chen@intel.com>
> -----Original Message-----
> From: Chen, Junjie J
> Sent: Thursday, March 15, 2018 12:24 AM
> To: Tan, Jianfeng; maxime.coquelin@redhat.com; yliu@fridaylinux.org
> Cc: dev@dpdk.org; Chen, Junjie J
> Subject: [PATCH v4] doc: add driver limitation for vhost dequeue zero copy
>
> 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 <junjie.j.chen@intel.com>
Reviewed-by: Jianfeng Tan <jianfeng.tan@intel.com>
Thanks!
> ---
> 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
> --
> 2.0.1
next prev parent reply other threads:[~2018-03-19 6:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-24 14:44 [dpdk-dev] [PATCH] " Junjie Chen
2018-02-26 4:44 ` Tan, Jianfeng
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 [this message]
2018-03-29 12:14 ` Maxime Coquelin
2018-04-11 14:34 ` Maxime Coquelin
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