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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> > > 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. 

Konstantin

> Examples: what about a zip compression in the forwarding plane?
> What about a VM2VM failover synchronization?