Re: [patch v4, kernel version 3.2.1] net/ipv4/ip_gre: Ethernetmultipoint GRE over IP

From: Štefan Gula
Date: Wed Jan 25 2012 - 17:57:38 EST


2012/1/25 David Miller <davem@xxxxxxxxxxxxx>:
> From: Jesse Gross <jesse@xxxxxxxxxx>
> Date: Tue, 24 Jan 2012 23:11:06 -0800
>
>> On Tue, Jan 24, 2012 at 8:02 PM, David Miller <davem@xxxxxxxxxxxxx> wrote:
>>> From: Joseph Glanville <joseph.glanville@xxxxxxxxxxxxxx>
>>> Date: Wed, 25 Jan 2012 14:48:37 +1100
>>>
>>>> The reason why this patch is useful is that it stands to be the only
>>>> true mulitpoint L2 VPN with a kernel space forwarding plane.
>>>
>>> So what you're telling me is that I added this huge openvswitch
>>> thing essentially for nothing?
>>
>> I think it's actually the opposite - Open vSwitch can be used to
>> implement this type of thing as well as for many other use cases.
>
> Then openvswitch is exactly where you should be prototyping and
> implementing support for this sort of stuff.
>
> And only if you cannot obtain reasonable performance using openvswitch
> should you be even entertaining the notion of a static implementation.
>
> That's the whole premise behind putting openvswitch into the tree, so
> that guys like you can play around in userspace without having to make
> any kernel changes at all.
>
> I am not applying these patches, the more things you say the more I am
> convinced they are not appropriate.
>
The performance is one of the most critical thing why I have chosen to
build kernel patch in the first place instead of some user-space app.
If I used this approach, I would probably end up with patch for
OpenVPN project instead in that time. I am not telling that
openvswitch is not a good place for prototyping, but I believe that
this patch is beyond that border as it successfully run in environment
with more 98 linux-based APs, used for 4K+ users, with no issue for
more than 2 years. The performance results from Joseph Glanville even
adds value to it. So I still don't get the point, why my patch and
openvswitch cannot coexists in the kernel together and let user/admin
to choose to correct solution for him/her.
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