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

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-02-24 15:14, Ananyev, Konstantin:
> 
> > > > 2016-02-24 10:22, Ananyev, Konstantin:
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> > > > > > Sent: Wednesday, February 24, 2016 10:10 AM
> > > > > > To: Thomas Monjalon
> > > > > > Cc: dev@dpdk.org; Kantecki, Tomasz
> > > > > > Subject: Re: [dpdk-dev] [PATCH] eal: Initial implementation of PQoS EAL extension
> > > > > >
> > > > > > 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.
> > > > >
> > > > > +1
> > > > > I also think it is a good thing to have.
> > > > > Again user don't have to trust the whitepapers - instead he can run the app
> > > > > and measure performance gain on his particular platform.
> > > >
> > > > I totally agree the example is good to have.
> > > > Konstantin, are you thinking it must be hosted in the PQoS lib repository?
> > >
> > > Personally I prefer it to be part of dpdk samples.
> > > DPDK IO code path is a bit different from what the 'classical' user app usually does -
> > > a lot of polling, avoid system calls, etc.
> > > Also it would probably have much better visibility here.
> > > Again, as Bruce already mentioned,  we have QAT & TAP samples, why we can't have PQoS too.
> > 
> > Indeed the DPDK policies are really flexible.
> > How would you suggest to decide which examples can enter in DPDK?
> 
> That's a good question, for which I don't have an exact answer.
> Probably a good opportunity for the TB to show itself :)
> My input would be - to justify new sample for dpdk+third-party-lib it has to demonstrate one of:
> a) clear performance gain for the existing dpdk application,
> i.e under scenario X with library Y dpdk app Z shows N% better performance.
> (PQos example).
> b) how to integrate dpdk based app with some well-known and widely used technology.
> (tap example, using fuse to implement vhost example).
> c) How to expand packet processing with the functionality that is not part of dpdk project. 
> So yes, if tomorrow someone will come up with example that does packet compression,
> or encryption or DPI using some third party library, I think we at least have to consider to
> include it inside dpdk.org/examples.
> 
>  As a restriction I would put that the example has to be relatively small and simple 
> and demonstrate particular feature usage. 
> Plus I think that this third-party library has to be freely available and open-sourced. 

It looks reasonnable.
I'd like we have such description in the doc (doc/guides/sample_app_ug/).
If everybody agree on such doc patch, we would have an official policy.