From: Avi Kivity <avi@scylladb.com>
To: Ferruh Yigit <ferruh.yigit@intel.com>, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH 1/3] kcp: add kernel control path kernel module
Date: Mon, 29 Feb 2016 12:58:42 +0200 [thread overview]
Message-ID: <56D42462.3020905@scylladb.com> (raw)
In-Reply-To: <56D420E5.9010802@intel.com>
On 02/29/2016 12:43 PM, Ferruh Yigit wrote:
> On 2/29/2016 9:43 AM, Avi Kivity wrote:
>> On 02/28/2016 10:16 PM, Ferruh Yigit wrote:
>>> On 2/28/2016 3:34 PM, Avi Kivity wrote:
>>>> On 01/27/2016 06:24 PM, Ferruh Yigit wrote:
>>>>> This kernel module is based on KNI module, but this one is stripped
>>>>> version of it and only for control messages, no data transfer
>>>>> functionality provided.
>>>>>
>>>>> This Linux kernel module helps userspace application create virtual
>>>>> interfaces and when a control command issued into that virtual
>>>>> interface, module pushes the command to the userspace and gets the
>>>>> response back for the caller application.
>>>>>
>>>>> The Linux tools like ethtool/ifconfig/ip can be used on virtual
>>>>> interfaces but not ones for related data, like tcpdump.
>>>>>
>>>>> In long term this patch intends to replace the KNI and KNI will be
>>>>> depreciated.
>>>> Instead of adding yet another out-of-tree kernel module, why not extend
>>>> the existing in-tree tap driver? This will make everyone's life easier.
>>>>
>>>> Since tap also supports data transfer, an application can also forward
>>>> packets not intended to it to the kernel, and forward packets from the
>>>> kernel through the device.
>>>>
>>> Hi Avi,
>>>
>>> KDP (Kernel Data Path) does what you have described, it is implemented
>>> as PMD and it benefits from tap driver to data transfer through the
>>> kernel. It also support custom kernel module for better performance.
>>>
>>> For KCP (Kernel Control Path), network driver forwards control commands
>>> to the userspace driver, I doubt this is something wanted for tun/tap
>>> driver, so extending tun/tap driver like this can be hard to upstream.
>> Have you tried asking? Maybe if you explain it they will be open to the
>> extension.
>>
> Not communicated but tun/tap already doing something different.
> For KCP, created interface is map of the DPDK port. All data interface
> shows coming from DPDK port. For example if you get stats information
> with ifconfig, the values you observe are DPDK port statistics -not
> statistics of data between userspace and kernelspace, statistics of data
> forwarded between DPDK ports. If you down the interface, DPDK port
> stopped, etc...
>
> If you extend the tun/tap, it won't be map of the DPDK port, and if you
> get statistics information from that interface, what do you expect to
> see, the data transferred between kernel and userspace, or underlying
> DPDK port forwarding statistics?
Good point. But you really have to involve netdev on this, or you'll
live out-of-tree forever.
> Extending tun/tap in a way we want, forwarding all control commands to
> userspace, will break the current tun/tap, this doesn't looks like a
> valid option to me.
It's possible to enhance it while preserving backwards compatibility, by
enabling a feature flag (statistics from userspace).
> For data path, using tun/tap is OK and we are already doing it, for the
> control path I believe we need a new driver.
>
>> Certainly it will be better to have KCP and KDP use the same kernel
>> interface name; so we'll need to either add data path support to kcp
>> (causing duplication with tap), or add control path support to tap. I
>> think the latter is preferable.
>>
> Why it is better to have same interface? Anyone who is not interested
> with kernel data path may want to control DPDK ports using common tools,
> or want to get some basic information and stats using ethtool or
> ifconfig. Why we need to bind two different functionality together?
Having two interfaces will be confusing for the user. If I wish to
firewall data packets coming from the dpdk port, do I set firewall rules
on dpdk0 or tap0?
I don't think it matters whether you extend tap, or add a data path to
kcp, but if you want to upstream it, it needs to be blessed by netdev.
>
>>> We are investigating about adding a native support to Linux kernel for
>>> KCP, but there is no task started for this right now, any support is
>>> welcome.
>>>
>>>
next prev parent reply other threads:[~2016-02-29 10:58 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1453911849-16562-1-git-send-email-ferruh.yigit@intel.com>
2016-01-27 16:24 ` Ferruh Yigit
2016-01-28 9:49 ` Remy Horton
2016-01-28 13:50 ` Ferruh Yigit
2016-02-28 15:34 ` Avi Kivity
2016-02-28 20:16 ` Ferruh Yigit
2016-02-29 9:43 ` Avi Kivity
2016-02-29 10:43 ` Ferruh Yigit
2016-02-29 10:58 ` Avi Kivity [this message]
2016-02-29 11:06 ` Thomas Monjalon
2016-02-29 11:35 ` Ferruh Yigit
2016-02-29 15:05 ` Ferruh Yigit
2016-02-29 15:19 ` Panu Matilainen
2016-02-29 15:27 ` Thomas Monjalon
2016-02-29 16:04 ` Panu Matilainen
2016-02-29 14:33 ` Jay Rolette
2016-03-01 22:40 ` Bruce Richardson
2016-03-02 2:02 ` Stephen Hemminger
2016-03-02 8:27 ` Panu Matilainen
2016-03-02 10:47 ` Vincent JARDIN
2016-03-02 10:51 ` Jim Thompson
2016-03-02 12:03 ` Vincent JARDIN
2016-03-02 22:51 ` Jim Thompson
2016-03-02 11:21 ` Thomas Monjalon
2016-03-02 22:35 ` Thomas Monjalon
2016-03-03 8:31 ` Panu Matilainen
2016-03-03 10:05 ` Ferruh Yigit
2016-03-03 10:11 ` Thomas Monjalon
2016-03-03 10:51 ` Panu Matilainen
2016-03-10 0:04 ` Thomas Monjalon
2016-03-10 6:31 ` Vincent JARDIN
2016-03-02 22:18 ` Jay Rolette
2016-03-03 10:11 ` Ferruh Yigit
2016-03-03 16:59 ` Stephen Hemminger
2016-03-03 18:18 ` Ferruh Yigit
2016-02-29 11:27 ` Ferruh Yigit
2016-02-29 11:39 ` Avi Kivity
2016-02-29 14:35 ` Ferruh Yigit
2016-02-29 20:11 ` Stephen Hemminger
2016-03-01 0:35 ` Ferruh Yigit
2016-01-27 16:24 ` [dpdk-dev] [PATCH 2/3] rte_ctrl_if: add control interface library Ferruh Yigit
2016-01-28 11:14 ` Remy Horton
2016-01-28 13:15 ` Ferruh Yigit
2016-01-28 13:24 ` Jay Rolette
2016-01-28 13:56 ` Ferruh Yigit
2016-01-28 13:57 ` Ananyev, Konstantin
2016-01-28 14:22 ` Yigit, Ferruh
2016-01-27 16:24 ` [dpdk-dev] [PATCH 3/3] examples/ethtool: add control interface support to the application Ferruh Yigit
2016-02-12 13:45 ` [dpdk-dev] [PATCH v2 0/3] Use common Linux tools to control DPDK ports Ferruh Yigit
2016-02-12 13:45 ` [dpdk-dev] [PATCH v2 1/3] kcp: add kernel control path kernel module Ferruh Yigit
2016-02-12 13:45 ` [dpdk-dev] [PATCH v2 2/3] rte_ctrl_if: add control interface library Ferruh Yigit
2016-02-17 19:58 ` Ananyev, Konstantin
2016-02-18 10:43 ` Yigit, Ferruh
2016-02-12 13:45 ` [dpdk-dev] [PATCH v2 3/3] examples/ethtool: add control interface support to the application Ferruh Yigit
2016-02-17 19:39 ` Ananyev, Konstantin
2016-02-18 10:11 ` Yigit, Ferruh
2016-02-26 14:10 ` [dpdk-dev] [PATCH v3 0/4] Use common Linux tools to control DPDK ports Ferruh Yigit
2016-02-26 14:10 ` [dpdk-dev] [PATCH v3 1/4] lib/librte_ethtool: move librte_ethtool form examples to lib folder Ferruh Yigit
2016-02-26 14:10 ` [dpdk-dev] [PATCH v3 2/4] kcp: add kernel control path kernel module Ferruh Yigit
2016-03-01 1:02 ` Stephen Hemminger
2016-03-01 15:53 ` Ferruh Yigit
2016-02-26 14:10 ` [dpdk-dev] [PATCH v3 3/4] rte_ctrl_if: add control interface library Ferruh Yigit
2016-02-26 14:10 ` [dpdk-dev] [PATCH v3 4/4] examples/ethtool: add control interface support to the application Ferruh Yigit
2016-02-29 9:33 ` [dpdk-dev] [PATCH v3 0/4] Use common Linux tools to control DPDK ports Remy Horton
2016-03-01 15:41 ` [dpdk-dev] [PATCH v4 " Ferruh Yigit
2016-03-01 15:41 ` [dpdk-dev] [PATCH v4 1/4] lib/librte_ethtool: move librte_ethtool form examples to lib folder Ferruh Yigit
2016-03-01 15:41 ` [dpdk-dev] [PATCH v4 2/4] kcp: add kernel control path kernel module Ferruh Yigit
2016-03-01 23:06 ` Stephen Hemminger
2016-03-02 11:05 ` Ferruh Yigit
2016-03-01 23:09 ` Stephen Hemminger
2016-03-01 23:10 ` Stephen Hemminger
2016-03-02 11:06 ` Ferruh Yigit
2016-03-01 15:41 ` [dpdk-dev] [PATCH v4 3/4] rte_ctrl_if: add control interface library Ferruh Yigit
2016-03-01 15:42 ` [dpdk-dev] [PATCH v4 4/4] examples/ethtool: add control interface support to the application Ferruh Yigit
2016-03-09 11:41 ` [dpdk-dev] [PATCH v5 0/4] Use common Linux tools to control DPDK ports Ferruh Yigit
2016-03-09 11:41 ` [dpdk-dev] [PATCH v5 1/4] lib/librte_ethtool: move librte_ethtool form examples to lib folder Ferruh Yigit
2016-03-09 11:41 ` [dpdk-dev] [PATCH v5 2/4] kcp: add kernel control path kernel module Ferruh Yigit
2016-03-09 11:41 ` [dpdk-dev] [PATCH v5 3/4] rte_ctrl_if: add control interface library Ferruh Yigit
2016-03-09 11:41 ` [dpdk-dev] [PATCH v5 4/4] examples/ethtool: add control interface support to the application Ferruh Yigit
2016-03-09 12:23 ` Ananyev, Konstantin
2016-03-14 15:31 ` [dpdk-dev] [PATCH v5 0/4] Use common Linux tools to control DPDK ports Ferruh Yigit
2016-03-14 17:40 ` Jay Rolette
2016-03-15 0:00 ` Ferruh Yigit
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