Re: [dpdk-dev] 2.3 Roadmap

["Wiles, Keith" <keith.wiles@intel.com>]

On 12/1/15, 10:54 AM, "dev on behalf of Richardson, Bruce" <dev-bounces@dpdk.org on behalf of bruce.richardson@intel.com> wrote:

>
>
>> -----Original Message-----
>> From: Aaron Conole [mailto:aconole@redhat.com]
>> Sent: Tuesday, December 1, 2015 3:31 PM
>> To: Richardson, Bruce <bruce.richardson@intel.com>
>> Cc: Panu Matilainen <pmatilai@redhat.com>; dev@dpdk.org
>> Subject: Re: [dpdk-dev] 2.3 Roadmap
>> 
>> Bruce Richardson <bruce.richardson@intel.com> writes:
>> > On Tue, Dec 01, 2015 at 04:58:08PM +0200, Panu Matilainen wrote:
>> >> On 12/01/2015 04:48 PM, Vincent JARDIN wrote:
>> >> >On 01/12/2015 15:27, Panu Matilainen wrote:
>> >> >>The problem with that (unless I'm missing something here) is that
>> >> >>KNI requires using out-of-tree kernel modules which makes it pretty
>> >> >>much a non-option for distros.
>> >> >
>> >> >It works fine with some distros. I do not think it should be an
>> argument.
>> >>
>> >> Its not a question of *working*, its that out-of-tree kernel modules
>> >> are considered unsupportable by the kernel people. So relying on KNI
>> >> would make the otherwise important and desireable tcpdump feature
>> >> non-existent on at least Fedora and RHEL where such modules are
>> >> practically outright banned by distro policies.
>> >>
>> >> 	- Panu -
>> >
>> > Yes, KNI is a bit of a problem right now in that way.
>> >
>> > How about a solution which is just based around the idea of setting up
>> > a generic port mirroring callback? Hopefully in the future we can get
>> > KNI exposed as a PMD, and we already have a ring PMD, and could
>> > possibly do a generic file/fifo PMD.
>> > Between the 3, we could then have multiple options for intercepting
>> > traffic going in/out of an app. The callback would just have to copy
>> > the traffic to the selected interface before returning it to the app as
>> normal?
>> >
>> > /Bruce
>> 
>> I'm actually working on a patch series that uses a TAP device (it's
>> currently been only minorly tested) called back from the port input. The
>> benefit is no dependancy on kernel modules (just TUN/TAP support). I don't
>> have a way of signaling sampling, so right now, it's just drinking from
>> the firehose. Nothing I'm ready to put out publicly (because it's ugly -
>> just a PoC), but it allows a few things:
>> 
>> 1) on demand on/off using standard linux tools (ifconfig/ip to set tap
>>    device up/down)
>> 2) Can work with any tool which reads off of standard linux interfaces
>>    (tcpdump/wireshark work out of the box, but you could plug in any
>>    pcap or non-pcap tool)
>> 3) Doesn't require changes to the application (no command line switches
>>    during startup, etc.)
>> 
>> As I said, I'm not ready to put it out there publicly, because I haven't
>> had a chance to check the performance, and it's definitely not following
>> any kind of DPDK-like coding style. Just wanted to throw this out as food
>> for thought - if you think this approach is worthwhile I can try to
>> prioritize it, at least to get an RFC series out.
>> 
>> -Aaron
>
>Once I had a generic file-handling PMD written, I was then considering extending
>it to work with TUN/TAP too. :-)
>I think a TAP PMD would be useful for the downstream distros who can't package
>KNI as it is right now.

In Pktgen I used tap interface to wireshark and that worked very nicely the only problem is it was slow :-(
Having a tap PMD would be nice to be able to remove that code from Pktgen.
>
>/Bruce
>


Regards,
Keith