Re: [dpdk-dev] Decoupling DPDK from EAL

[Jason Vassbender <jason.vassbender@gmail.com>]

Hi,

The memory allocation is not an issue since that is contained entirely
within DPDK itself and does not leak outside, i.e. all DPDK data
structures are managed with DPDK memory management functions and
that's valid and OK.

The thread model integration issue is because EAL creates its own
threads and sets its own affinities/priorities. My current plan is
indeed to wrap the DPDK thread stuff with my our own threading
facilities, so that when the DPDK thread starts up and calls my
function i will set up our own threading meta-data structures and set
the proper affinity/priority, then call our processing loop that
expects our meta-data to be in place.

As for the command line arguments; I plan to synthesize the command
line parameters that EAL expects, and then provide them to it in the
form of argc/argv so that i can do late-initialization via e.g.
external configuration data that I receive over the network after the
application is already running.

-Jason

On Wed, Dec 4, 2013 at 3:37 PM, François-Frédéric Ozog <ff@ozog.com> wrote:
> Hi,
>
> I think I get the picture. DPDK is not really flexible at memory allocation
> (nor the Linux kernel which requires boot parameters for 1GB huge pages)...
> Let's assume that "static" memory configuration is acceptable.
>
> Is the thread model integration issue related to the fact we set affinity
> ATFER thread creation? (I agree this is complex, but you can still create an
> adaptation layer in your thread API to accommodate DPDK thread model).
>
> François-Frédéric
>
>
>> -----Message d'origine-----
>> De : Jason Vassbender [mailto:jason.vassbender@gmail.com]
>> Envoyé : mercredi 4 décembre 2013 10:25
>> À : François-Frédéric Ozog
>> Cc : dev@dpdk.org
>> Objet : Re: [dpdk-dev] Decoupling DPDK from EAL
>>
>> Hey,
>>
>> I guess the main hurdle is that we already have our own multi-threaded
>> architecture and ways to control thread startup/shutdown, priorities and
>> affinities and they are all balanced very delicately (our application is
>> latency sensitive, runs on rt_preempt, boots with isolcpus, etc). In
>> addition, we are already using the command line to initialize some of our
>> things, and part of the configuration for the application does not even
>> come from the command line, but from eg.
>> XML configuration file over the network. So ideally what I would have
>> preferred is that EAL initialization could be done by other means (for
>> example a simple initialization function with a dictionary as to be more
>> flexible) and thread creation/shutdown could be left to the application if
>> it so desires, provided it meets the execution conditions expected by
> DPDK.
>>
>> Essentially, at its current state, DPDK offers a complete solution to your
>> problem including the entire surrounding framework. But for most big
>> applications they already have their own frameworks in place and
>> integrating DPDK becomes harder than it should be. So if DPDK were to be
>> decoupled from EAL, made more modular, and some of the functions
> optionally
>> left to applications to provide if they already have the facilities for
>> them would make integration much easier and more flexible.
>>
>> -Jason
>>
>> On Wed, Dec 4, 2013 at 10:27 AM, François-Frédéric Ozog <ff@ozog.com>
>> wrote:
>> > Hi,
>> >
>> > I just completed such a consulting mission for a customer. They were
>> > using libpcap as the network back end and the most challenging hurdle
>> > was to transform a single threaded capture architecture to a
>> > multi-threaded one with DPDK. The other key take away, is that DPDK
>> > capture helps to get only 20% of the 20 times performance boost I
>> > managed to achieve: most of the latency is due to "application" and
> other
>> internal communication mechanisms.
>> >
>> > So I agree that DPDK is not light, but I think most of the power of
>> > DPDK comes from EAL thread management and "IPC"...
>> >
>> > Having said all that, I may have missed a critical point, so, what is
>> > the specific major hurdle you see in the integration?
>> >
>> > François-Frédéric
>> >
>> >
>> >> -----Message d'origine-----
>> >> De : dev [mailto:dev-bounces@dpdk.org] De la part de Jason Vassbender
>> >> Envoyé : mardi 3 décembre 2013 22:51 À : dev@dpdk.org Objet :
>> >> [dpdk-dev] Decoupling DPDK from EAL
>> >>
>> >> Hello,
>> >>
>> >> I am trying to integrate DPDK into an existing application in order
>> >> to improve packet processing latency, but it is proving rather
>> >> difficult because of DPDK's dependency on EAL's thread management and
>> >> bootstrap mechanism. Our application already has its own framework
>> >> for managing threads and their affinities/priorities, IPC, timers and
>> >> its own bootstrap mechanism (not necessarily via command line
>> >> arguments), we wish to integrate DPDK as an alternative network
>> >> back-end, but it wants to to take over our entire way of doing things.
>> >>
>> >> Are there any plans to decouple DPDK's core functionality away from
>> >> EAL so that it can be more easily integrated into existing
> applications?
>> >>
>> >> -Jason
>> >
>