From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Chas Williams <3chas3@gmail.com>, Thomas Monjalon <thomas@monjalon.net>
Cc: Chas Williams <chas3@att.com>,
dev@dpdk.org, skhare@vmware.com, stable@dpdk.org
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] net/vmxnet3: keep link state consistent
Date: Tue, 17 Apr 2018 20:25:59 +0100 [thread overview]
Message-ID: <7001889b-9a98-c353-ad9c-207bffc6869a@intel.com> (raw)
In-Reply-To: <CAG2-Gk=iqowLDZ2fFqa_5K437g+uFjTCiaJYiKCBV29uA5g3Xw@mail.gmail.com>
On 4/5/2018 4:01 PM, Chas Williams wrote:
> On Thu, Apr 5, 2018 at 6:03 AM, Thomas Monjalon <thomas@monjalon.net> wrote:
>> 20/03/2018 15:12, Ferruh Yigit:
>>> On 3/18/2018 1:45 AM, Chas Williams wrote:
>>>> From: Chas Williams <chas3@att.com>
>>>>
>>>> The vmxnet3 never attempts link speed negotiation. As a virtual device
>>>> the link speed is vague at best. However, it is important for certain
>>>> applications, like bonding, to see a consistent link_status. 802.3ad
>>>> requires that only links of the same cost (link speed) be enslaved.
>>>> Keeping the link status consistent in vmxnet3 avoids races with bonding
>>>> enslavement.
>>
>> I don't understand the issue.
>> Are you sure it is not an issue in bonding?
>
> 802.3ad "requires" you to bond together links of the same speed and duplex. The
> primary reason for this (or so I gather) is to ensure that the
> spanning-tree cost for
> each port is the same. If you fail from one link to another, you
> don't want a spanning
> tree reconfiguration.
>
> The problem exists in general for most of the PMDs -- see
> https://dpdk.org/ml/archives/dev/2018-April/094696.html
>
> The problem is more vexing for AUTONEG and bonding. I am still thinking about
> that. You don't know until you go to activate the slave and bonding
> only makes its
> check during the setup phase. So for virtual adapters and bonding, not using
> AUTONEG makes more sense because it is just easier to handle.
>
>>
>> About the right value to set for virtual PMDs, I don't know, both are fakes.
>> I thought that AUTONEG better convey the vague link speed you describe.
>
> It's not vague. There is no negotiation of any sort. The link speed
> (and therefore cost)
> of the link is fixed. While the particular rate you get from the
> adapter depends
> on a number of factors, the link speed isn't going to change. The
> adapter is not
> going to change the link speed from 10G to 1G or change from full duplex to half
> duplex.
Hi Chas, Thomas,
What is the latest status of this patch? Is it agreed to convert link_autoneg to
ETH_LINK_FIXED for following PMDs [1]?
[1]
pcap
softnic
vmxnet3
>
>>
>>
>>>> Author: Thomas Monjalon <thomas@monjalon.net>
>>>> Date: Fri Jan 5 18:38:55 2018 +0100
>>>>
>>>> Fixes: 1e3a958f40b3 ("ethdev: fix link autonegotiation value")
>>>> Cc: stable@dpdk.org
>>>
>>> There were a few more PMDs [1] they have been updated from FIXED to AUTONEG with
>>> above commit, do you think should we update them back to FIXED as well?
>>>
>>> [1]
>>> pcap
>>> softnic
>>> vmxnet3
>>
>> Yes, they all can be fixed/LINK_FIXED :) I guess
>>
>>
>>
next prev parent reply other threads:[~2018-04-17 19:26 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-18 1:45 [dpdk-stable] " Chas Williams
2018-03-20 14:12 ` Ferruh Yigit
2018-03-20 14:42 ` Chas Williams
2018-04-05 10:03 ` [dpdk-stable] [dpdk-dev] " Thomas Monjalon
2018-04-05 15:01 ` Chas Williams
2018-04-17 19:25 ` Ferruh Yigit [this message]
2018-04-17 20:24 ` Thomas Monjalon
2018-04-18 16:23 ` Ferruh Yigit
2018-04-18 16:59 ` Yong Wang
2018-04-20 0:10 ` [dpdk-stable] " Ferruh Yigit
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