[dpdk-dev] transmit functions of dpdk

[Sachin Sharma]

Hi Bruce,

>>>I'm not entirely clear on what you mean by filling one queue and
emptying another. Is this just a form of buffering you are trying to
implement?

Yes, you are right! I am implementing a buffering mechanism in which a node
will have three queues and it  fills one queue with packets and when the
queue is full then transmit the packets from the queue to the wire and
while filling one queue, it can transmit packets to a wire through another
queue that is already full.

Thanks & Regards,
Sachin.




On Wed, Dec 10, 2014 at 12:45 PM, Bruce Richardson <
bruce.richardson at intel.com> wrote:

> On Wed, Dec 10, 2014 at 12:31:27PM +0100, Sachin Sharma wrote:
> > Hi Bruce,
> >
> > In my use case, I want to have three NIC TX queues per port, and want to
> > fill one NIC TX queue and want to empty the other queue. Is it possible
> > this through tx_burst or do I need to implement these queues in
> > applications as you suggested before. However, in this case, I would have
> > then one NIC TX queues and three queues in an application which actually
> > transmits packets to this NIC TX queue. Am I right?
> >
>
> For the suggestion I made, yes, you would have three software queues in
> your
> application, and a single TX on the NIC - though you could also have a 1:1
> mapping
> of software to HW queues if you wanted.
> However, I'm not entirely clear on what you mean by filling one queue and
> emptying
> another. Is this just a form of buffering you are trying to implement?
>
> > Thanks,
> > Sachin.
> >
> > On Wed, Dec 10, 2014 at 12:22 PM, Bruce Richardson <
> > bruce.richardson at intel.com> wrote:
> >
> > > On Wed, Dec 10, 2014 at 12:03:41PM +0100, Sachin Sharma wrote:
> > > > Dear all,
> > > >
> > > >  In my algorithm, I am interested to perform  two activities - (1)
> > > > transmitting packets to a tx_queue and (2) transmitting packets from
> > > > tx_queue to a wire - separately. I have gone through the code by
> putting
> > > > logs in the dpdk code and found that there is a function
> rte_eth_tx_burst
> > > > which transmits packets to a specific queue. However, when I debugged
> > > more
> > > > then I found that this function just calls eth_igb_xmit_pkts
> > > > from librte_pmd_e1000, and this function just directly write the
> packets
> > > to
> > > > the wire by writing all packets into registers. Could you please
> suggest
> > > > how to implement these two functions if these are not implemented
> already
> > > > in dpdk?
> > > >
> > > >
> > > >
> > > > Thanks & Regards,
> > > > Sachin.
> > >
> > > Hi Sachin,
> > >
> > > anything written to the NIC TX queue is automatically put onto the wire
> > > unless
> > > the NIC port is down or the wire is unplugged etc. What is your
> use-case
> > > that you
> > > need to do this? I would suggest doing internal buffering in your
> > > application,
> > > as many DPDK example applications do, and then call tx_burst to put
> your
> > > packets
> > > on the wire when you want this capability.
> > >
> > > Regards,
> > > /Bruce
> > >
>