[dpdk-users] Packet spacing in DPDK

[dpdk-users] Packet spacing in DPDK

[Vijay]

Hi,

I am new to this mailing list and new to DPDK. I would like to know about
packet spacing when a burst of packets are being transmitted. For example:
there is a timer running and at expiry of the timer there could multiple
frames that need to transmitted. So, will these frames be spaced by dpdk
before transmission ? Is it internally handled by dpdk ? Is there any doc
that talks about this ?

I am not sure if this question has already been asked. If yes, please point
me to the appropriate thread which talks about this.

Thanks,
Vijay

Re: [dpdk-users] Packet spacing in DPDK

[Stephen Hemminger]

On Thu, 8 Jun 2017 09:50:05 -0700
Vijay <vjmohanc@gmail.com> wrote:

> Hi,
> 
> I am new to this mailing list and new to DPDK. I would like to know about
> packet spacing when a burst of packets are being transmitted. For example:
> there is a timer running and at expiry of the timer there could multiple
> frames that need to transmitted. So, will these frames be spaced by dpdk
> before transmission ? Is it internally handled by dpdk ? Is there any doc
> that talks about this ?
> 
> I am not sure if this question has already been asked. If yes, please point
> me to the appropriate thread which talks about this.
> 
> Thanks,
> Vijay

The packets in DPDK are not paced. The hardware sends them as fast as possible.

Re: [dpdk-users] Packet spacing in DPDK

[Vijay]

So, for example, at every 1 Sec interval if 1000 packets need to
transmitted, then HW tries to send them as fast as possible ? Is there any
document which talks about this ?

On Thu, Jun 8, 2017 at 10:25 AM, Stephen Hemminger <
stephen@networkplumber.org> wrote:

> On Thu, 8 Jun 2017 09:50:05 -0700
> Vijay <vjmohanc@gmail.com> wrote:
>
> > Hi,
> >
> > I am new to this mailing list and new to DPDK. I would like to know about
> > packet spacing when a burst of packets are being transmitted. For
> example:
> > there is a timer running and at expiry of the timer there could multiple
> > frames that need to transmitted. So, will these frames be spaced by dpdk
> > before transmission ? Is it internally handled by dpdk ? Is there any doc
> > that talks about this ?
> >
> > I am not sure if this question has already been asked. If yes, please
> point
> > me to the appropriate thread which talks about this.
> >
> > Thanks,
> > Vijay
>
> The packets in DPDK are not paced. The hardware sends them as fast as
> possible.
>

Re: [dpdk-users] Packet spacing in DPDK

[Shepard Siegel]

Even though DPDK sends packets down to the hardware as fast as possible,
which is a great thing; it can also send down useful metadata. Some
merchant NIC ASICs have hardware to support egress pacing, which their DPDK
PMDs may or may not expose. Last year with our FPGA-based Arkville product,
we developed a prototype "Paced Packet Player" which used TX/egress packet
metadata to determine each individual packet's release to the MAC TX port,
packet-by-packet. To ns precision. On four parallel 100 GbE ports. I
blogged about it here.

http://atomicrules.blogspot.co.uk/2017/01/paced-packet-player.html

The point is, that depending on your ability to add some dedicated logic
just ahead of the TX MAC; DPDK's TX metadata can be used to provide egress
packet-pacing to hardware. If or not your particular NIC can use this data
is a function of your NIC hardware and the associated PMD.

-Shep



On Thu, Jun 8, 2017 at 1:51 PM, Vijay <vjmohanc@gmail.com> wrote:

> So, for example, at every 1 Sec interval if 1000 packets need to
> transmitted, then HW tries to send them as fast as possible ? Is there any
> document which talks about this ?
>
> On Thu, Jun 8, 2017 at 10:25 AM, Stephen Hemminger <
> stephen@networkplumber.org> wrote:
>
> > On Thu, 8 Jun 2017 09:50:05 -0700
> > Vijay <vjmohanc@gmail.com> wrote:
> >
> > > Hi,
> > >
> > > I am new to this mailing list and new to DPDK. I would like to know
> about
> > > packet spacing when a burst of packets are being transmitted. For
> > example:
> > > there is a timer running and at expiry of the timer there could
> multiple
> > > frames that need to transmitted. So, will these frames be spaced by
> dpdk
> > > before transmission ? Is it internally handled by dpdk ? Is there any
> doc
> > > that talks about this ?
> > >
> > > I am not sure if this question has already been asked. If yes, please
> > point
> > > me to the appropriate thread which talks about this.
> > >
> > > Thanks,
> > > Vijay
> >
> > The packets in DPDK are not paced. The hardware sends them as fast as
> > possible.
> >
>