[dpdk-dev] DPDK Enqueue Pipeline

[Avinash .]

Thank you for the clarification. I was trying to get the queue and traffic
class information from where the packet is going to be dequeued. Its
resolved now.

Regards
Avinash

On Fri, Feb 28, 2020 at 7:09 PM Singh, Jasvinder <jasvinder.singh at intel.com>
wrote:

>
>
> > -----Original Message-----
> > From: dev <dev-bounces at dpdk.org> On Behalf Of Avinash .
> > Sent: Wednesday, February 26, 2020 10:46 AM
> > To: dev at dpdk.org
> > Cc: Gokul Bargaje <gokulbargaje.182009 at nitk.edu.in>; Mohit P. Tahiliani
> > <tahiliani at nitk.edu.in>
> > Subject: [dpdk-dev] DPDK Enqueue Pipeline
> >
> > Hi all,
> > The DPDK QoS scheduler has a 4-stage pipeline for enqueuing the packets.
> > This is used for hiding the latency of prefetching the data structures.
> > Why is there no pipeline for dequeuing the packets?
>
> The dequeue operation happens in stages that involves scanning bitmap
> (that contains the active pipes info), followed by extracting information
> about TC and queue of the pipe that will be considered for scheduling. As a
> result, the information about pipe TC and queue become
>  available but not exposed to the application as this is internal to
> dequeue operation.
>
> > How does the dequeue function maintain the state of a packet? In other
> > words, if I want to backtrace the packet that is dequeued to get the
> info of
> > what was the traffic class and from which queue the packet was dequeued.
> > Is there any way to get this.
> >
> The QoS dequeue operation is built around multiple grinders (packet
> crunching engines) that works on different pipes at a time. Each grinder
> follows the state machine (please have a look at the documentation) which
> contains multiple stages starting from pipe bitmap scanning, tc and queue
> detection, fetching the packet from the queue based on the available
> credits, etc, all this information is kept in internal data structure of
> the scheduler, and that info can be used to understand the flow or debug
> the code.  why you want to expose that intermediate info through public API
> during execution?
>
>
> > Regards
> >
> > --
> > Avinash
>