Re: [dpdk-dev] [PATCH] eal: Initial implementation of PQoS EAL extension

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Feb 24, 2016 at 11:31:47AM +0100, Thomas Monjalon wrote:
> 2016-02-24 10:10, Bruce Richardson:
> > On Wed, Feb 24, 2016 at 09:24:33AM +0100, Thomas Monjalon wrote:
> > > 2016-02-23 23:03, Kantecki, Tomasz:
> > > > > From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> > > > > If there is nothing specific in DPDK for PQos, why writing an example in
> > > > > DPDK?
> > > > The example makes it much easier to use the technology with DPDK.
> > > > 
> > > > > Maybe the example should be better in the library itself.
> > > > The library in question (https://github.com/01org/intel-cmt-cat) has a couple of examples but none of them refers to DPDK.
> > > > 
> > > > > I suggest to mention the library in
> > > > > doc/guides/linux_gsg/nic_perf_intel_platform.rst
> > > > Ok it can be added to this document. Does it imply -1 for the sample code idea?
> > > 
> > > I may be wrong but I have the feeling the example is more about PQoS than DPDK.
> > > So yes, I would vote -1.
> > > 
> > Well, the intersection of DPDK and PQoS is what the example is really all about,
> > and as such it is relevant to both DPDK and the library itself. Platform QoS
> > can be of great use to packet processing applications for helping to ensure that
> > the app gets the resources it needed - especially in a virtualised world - and
> > so we believe that having an example in DPDK showing how to use PQoS with DPDK
> > is well worthwhile having. It's more effective than a simple doc update in
> > raising awareness of the existence of the feature, and also provides for DPDK
> > users a readily available app for the user to start playing with to evaluate
> > PQoS for their own use-cases.
> > I also fail to see what the downside of having the sample app is - it won't add
> > significantly to the project maintenance overhead.
> 
> We need to draw a line in the sand to decide what can go in DPDK examples because
> any code using some DPDK functions could require to be integrated.
> Until now, the examples were used to demonstrate some DPDK API.
> Here you are advocating that examples are "marketing tools" to bring awareness on
> a library.
> I have no strong opinion, except that we cannot host and maintain 100 examples.
> Other opinions are welcome.

I think it comes down to whether it contributes something that would be useful
and appreciated by the users. 

[While the majority of sample apps have been for showing off DPDK APIs, that's
not exclusively the case. There is the DPDK-QAT example, and also the
exception_path example showing how to use DPDK with TUN/TAP. I believe both
these add value for DPDK users and these examples, and others like them,
are worth having.]

So, in summary, I honestly think that having an example that shows platform 
QoS functionality being used with DPDK is worth having as it is something that
would be useful to DPDK users.

/Bruce