From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>,
"aconole@redhat.com" <aconole@redhat.com>,
"sodey@sonusnet.com" <sodey@sonusnet.com>,
"yuanhan.liu@linux.intel.com" <yuanhan.liu@linux.intel.com>,
"thomas.monjalon@6wind.com" <thomas.monjalon@6wind.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v3 7/9] net/virtio: Add MTU feature support
Date: Mon, 10 Apr 2017 06:48:36 +0000 [thread overview]
Message-ID: <ED26CBA2FAD1BF48A8719AEF02201E365119A998@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <1e0af6da-cb01-fb91-c0b0-efa08ebd9f21@redhat.com>
> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> Sent: Saturday, April 8, 2017 12:41 AM
> To: Tan, Jianfeng; aconole@redhat.com; sodey@sonusnet.com;
> yuanhan.liu@linux.intel.com; thomas.monjalon@6wind.com; dev@dpdk.org
> Subject: Re: [PATCH v3 7/9] net/virtio: Add MTU feature support
>
> Hi Jianfeng,
>
> On 04/05/2017 04:50 PM, Tan, Jianfeng wrote:
> >
> >
> > On 4/5/2017 9:54 PM, Maxime Coquelin wrote:
> >>
> >>
> >> On 04/05/2017 11:42 AM, Tan, Jianfeng wrote:
> >>> Hi Maxime,
> >>>
> >>> Thank you for replying.
> >>>
> >>> On 4/5/2017 3:11 PM, Maxime Coquelin wrote:
> >>>> Hi Jianfeng,
> >>>>
> >>>> On 04/05/2017 06:52 AM, Tan, Jianfeng wrote:
> >>>>> Hi Maxime,
> >>>>>
> >>>>> Have some confusion about this feature. Please help confirm.
> >>>>>
> >>>>> (1) With this feature, we only support to advertise MTU value which is
> >>>>> defined by QEMU to frontend and backend driver separately. (2) But
> it
> >>>>> does not allow frontend driver to set a different MTU to QEMU and
> then
> >>>>> to vhost backend.
> >>>>>
> >>>>> Correct?
> >>>>> If it's correct, why not MTU works like (2)?
> >>>>
> >>>> Because idea is that the hosts advertises the maximum MTU value it
> >>>> supports. The frontend driver is free to use a smaller value. The goal
> >>>> of this change is to make possible to set a uniform MTU value across
> >>>> the infrastructure, the management tools giving a hint to the guests on
> >>>> the MTU value it should use.
> >>>
> >>> Based on that MTU is the maximum packet size that can be sent instead
> of
> >>> that can be received:
> >>> (1) Why vhost (as a device) does not drop any packets which are longer
> >>> than MTU when dequeue()?
> >> That's a good point.
> >> As when MTU value is negotiated, the guest agrees not to send larger
> >> packets. But we cannot trust the guest, so vhost needs to check the
> >> packet length.
> >>
> >>> (2) See some NICs also use MTU to calculate maximum packet size that
> can
> >>> be received, like ixgbe, i40e, shall we also do that?
> >> Can you give me some pointers to the code?
> >
> > Please refer ixgbe_dev_mtu_set(), and i40e_dev_mtu_set().
>
> Thanks. Yes, we could also do that.
>
> I can send a patch for this and another one to check the size of the
> packet respects negotiated MTU value. Or maybe you want to do this?
I'll help review then.
Thanks,
Jianfeng
next prev parent reply other threads:[~2017-04-10 6:48 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-13 14:28 [dpdk-dev] [PATCH 0/7] virtio/vhost: " Maxime Coquelin
2017-02-13 14:28 ` [dpdk-dev] [PATCH 1/7] vhost: Enable VIRTIO_NET_F_MTU feature Maxime Coquelin
2017-02-13 14:28 ` [dpdk-dev] [PATCH 2/7] vhost: vhost-user: Add MTU protocol feature support Maxime Coquelin
2017-02-13 14:28 ` [dpdk-dev] [PATCH 3/7] vhost: Add new ready status flag Maxime Coquelin
2017-02-13 14:28 ` [dpdk-dev] [PATCH 4/7] vhost: Add API to get/set MTU value Maxime Coquelin
2017-02-13 14:28 ` [dpdk-dev] [PATCH 5/7] net/vhost: Implement mtu_set callback Maxime Coquelin
2017-02-13 14:28 ` [dpdk-dev] [PATCH 6/7] net/virtio: Add MTU feature support Maxime Coquelin
2017-02-16 19:31 ` Aaron Conole
2017-02-16 21:17 ` Maxime Coquelin
2017-02-13 14:28 ` [dpdk-dev] [PATCH 7/7] app/testpmd: print MTU value in show port info Maxime Coquelin
2017-02-23 7:10 ` [dpdk-dev] [PATCH 0/7] virtio/vhost: Add MTU feature support Yuanhan Liu
2017-03-01 7:44 ` Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 " Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 1/7] vhost: Enable VIRTIO_NET_F_MTU feature Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 2/7] vhost: vhost-user: Add MTU protocol feature support Maxime Coquelin
2017-03-08 2:31 ` Yuanhan Liu
2017-03-12 10:24 ` Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 3/7] vhost: Add new ready status flag Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 4/7] vhost: Add API to get MTU value Maxime Coquelin
2017-03-08 2:45 ` Yuanhan Liu
2017-03-12 10:23 ` Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 5/7] net/vhost: Fill rte_eth_dev's MTU property Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 6/7] net/virtio: Add MTU feature support Maxime Coquelin
2017-03-06 8:27 ` [dpdk-dev] [PATCH v2 7/7] app/testpmd: print MTU value in show port info Maxime Coquelin
2017-03-07 21:57 ` [dpdk-dev] [PATCH v2 0/7] virtio/vhost: Add MTU feature support Thomas Monjalon
2017-03-12 10:00 ` Maxime Coquelin
2017-03-12 16:33 ` [dpdk-dev] [PATCH v3 0/9] " Maxime Coquelin
2017-03-12 16:33 ` [dpdk-dev] [PATCH v3 1/9] vhost: Enable VIRTIO_NET_F_MTU feature Maxime Coquelin
2017-03-12 16:33 ` [dpdk-dev] [PATCH v3 2/9] vhost: vhost-user: Add MTU protocol feature support Maxime Coquelin
2017-03-12 16:34 ` [dpdk-dev] [PATCH v3 3/9] vhost: Add new ready status flag Maxime Coquelin
2017-03-12 16:34 ` [dpdk-dev] [PATCH v3 4/9] vhost: Add API to get MTU value Maxime Coquelin
2017-03-16 8:00 ` Yuanhan Liu
2017-03-16 11:37 ` Maxime Coquelin
2017-03-17 5:32 ` Yuanhan Liu
2017-03-17 9:59 ` Maxime Coquelin
2017-03-20 8:42 ` Yuanhan Liu
2017-03-12 16:34 ` [dpdk-dev] [PATCH v3 5/9] vhost: export " Maxime Coquelin
2017-03-12 16:34 ` [dpdk-dev] [PATCH v3 6/9] net/vhost: Fill rte_eth_dev's MTU property Maxime Coquelin
2017-03-12 16:34 ` [dpdk-dev] [PATCH v3 7/9] net/virtio: Add MTU feature support Maxime Coquelin
2017-04-05 4:52 ` Tan, Jianfeng
2017-04-05 7:11 ` Maxime Coquelin
2017-04-05 9:42 ` Tan, Jianfeng
2017-04-05 13:54 ` Maxime Coquelin
2017-04-05 14:50 ` Tan, Jianfeng
2017-04-07 16:40 ` Maxime Coquelin
2017-04-10 6:48 ` Tan, Jianfeng [this message]
2017-03-12 16:34 ` [dpdk-dev] [PATCH v3 8/9] doc: announce Virtio and Vhost MTU support Maxime Coquelin
2017-03-12 16:34 ` [dpdk-dev] [PATCH v3 9/9] app/testpmd: print MTU value in show port info Maxime Coquelin
2017-03-22 8:58 ` [dpdk-dev] [PATCH v3 0/9] virtio/vhost: Add MTU feature support Yuanhan Liu
2017-03-22 9:03 ` Maxime Coquelin
2017-03-28 5:39 ` Yao, Lei A
2017-03-30 11:34 ` Maxime Coquelin
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