[dpdk-dev] Why IP_PIPELINE is faster than L2FWD

[Royce Niu]

Dear Bruce,

Thanks for your kind explanation.

I will try to follow your suggestion and see the source code.

On Thu, Dec 22, 2016 at 9:25 PM, Bruce Richardson <
bruce.richardson at intel.com> wrote:

> On Thu, Dec 22, 2016 at 08:48:50PM +0800, Royce Niu wrote:
> > But, actually, L3FWD of IP_PIPELINE is also faster than stock L2FWD,
> which
> > also modifies mac addr. How can explain this?
> >
> > Actually, I want to know why IP_PIPELINE is much faster and I can learn
> > from IP_PIPELINE and make our own program.
> >
> > But, the documentation of that is not detailed enough. if it is possible,
> > could you tell me where is the key to boost? Thanks!
> >
>
> Adding Cristian as IP Pipeline maintainer.
>
> A lot of tuning work went into IP Pipeline and the table and port
> libraries it uses, so I'm not sure that there is just one or two key
> changes which give it such good performance. L2 forward just hasn't had
> the same level of tuning and, while performing well, is also simplified
> to make it understandable as an example. Contrast the code in l2fwd
> against equivalent vector code in l3fwd-lpm* files e.g. l3fwd_lpm_sse.h.
> The latter is very high performing, the former is more readable.
>
> Regards,
> /Bruce
>
> > On Thu, Dec 22, 2016 at 7:15 PM, Bruce Richardson <
> > bruce.richardson at intel.com> wrote:
> >
> > > On Thu, Dec 22, 2016 at 12:18:12AM +0800, Royce Niu wrote:
> > > > Hi all,
> > > >
> > > > I tested default L2FWD and IP_PIPELINE (pass-through). The
> throughput of
> > > > IP_PIPELINE is higher immensely.
> > > >
> > > > There are only two virtual NICs in KVM. The experiment is just moving
> > > > packet from vNIC0  to vNIC1. I think the function is so simple. Why
> L2FWD
> > > > is much slower?
> > > >
> > > > How can I improve L2FWD, to make L2FWD faster?
> > > >
> > > Is IP_PIPELINE in passthrough mode modifying the packets? L2FWD swaps
> > > the mac addresses on each packet as it processes them, which can slow
> it
> > > down. L2FWD is also more an example of how the APIs work than anything
> > > else. For fastest possible port-to-port forwarding, testpmd should give
> > > the highest performance.
> > >
> > > /Bruce
> > >
> >
> >
> >
> > --
> > Regards,
> >
> > Royce
>



-- 
Regards,

Royce