From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: "Tan, Jianfeng" <jianfeng.tan@intel.com>,
aconole@redhat.com, sodey@sonusnet.com,
yuanhan.liu@linux.intel.com, thomas.monjalon@6wind.com,
dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v3 7/9] net/virtio: Add MTU feature support
Date: Wed, 5 Apr 2017 15:54:00 +0200 [thread overview]
Message-ID: <d40fba46-0ce2-7943-ea25-bfd67a619188@redhat.com> (raw)
In-Reply-To: <a832d123-c086-f0a5-7d1f-649f825c1041@intel.com>
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?
Thanks,
Maxime
next prev parent reply other threads:[~2017-04-05 13:54 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 [this message]
2017-04-05 14:50 ` Tan, Jianfeng
2017-04-07 16:40 ` Maxime Coquelin
2017-04-10 6:48 ` Tan, Jianfeng
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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