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From: Cong Wang <cwang@twopensource.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev <netdev@vger.kernel.org>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	David Miller <davem@davemloft.net>
Subject: Re: Why do we prefer skb->priority to tc filters?
Date: Wed, 11 Mar 2015 12:18:16 -0700	[thread overview]
Message-ID: <CAHA+R7Pa6ypGoUr5jJfbayzwjLA-C78NOa1iPmsbmx+wXP56AA@mail.gmail.com> (raw)
In-Reply-To: <1426098340.11398.59.camel@edumazet-glaptop2.roam.corp.google.com>

On Wed, Mar 11, 2015 at 11:25 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Wed, 2015-03-11 at 11:08 -0700, Cong Wang wrote:
>> On Wed, Mar 11, 2015 at 10:34 AM, Cong Wang <cwang@twopensource.com> wrote:
>> >
>> > Given that skb->priority can be specified in user-space, doesn't this
>> > mean some application can always override our rules specified by tc
>> > filters? I think we should always respect tc filters over any
>> > application setting.
>> >
>>
>> Hmm, on the other hand, skb->priority can be changed in cgroup
>> too, in this case the current behavior seems correct. :-/ Interesting.
>
> Note that even HTB has the following code :
>

I am not surprised.

[...]

>
> So if skb->priority happens to match sch->handle or any class handle,
> we queue packet into a queue, without calling tc_classify()

This is exactly why I am asking, kernel respects user's choice so much
that it could override even both cgroup prio and tc filters, I don't know
what is the reason behind, but this means our tc filters can not work
with an application which sets skb->priority. For example, our tc filters
classify the packets from this socket into flow 1:1, but application
sets 1:2 by itself...

  reply	other threads:[~2015-03-11 19:18 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-11 17:34 Why do we prefer skb->priority to tc filters? Cong Wang
2015-03-11 18:08 ` Cong Wang
2015-03-11 18:25   ` Eric Dumazet
2015-03-11 19:18     ` Cong Wang [this message]
2015-03-11 20:09       ` Eric Dumazet
2015-03-11 20:46         ` Cong Wang
2015-03-11 21:47           ` Eric Dumazet
2015-03-11 22:12             ` Cong Wang
2015-03-12  0:00               ` Eric Dumazet
2015-03-12 16:59                 ` Cong Wang
2015-03-12 17:25                   ` Cong Wang
2015-03-12  7:53             ` Dmitry Sytchev
2015-03-12 17:08               ` Cong Wang

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