Re: [dpdk-dev] Why IP_PIPELINE is faster than L2FWD

["Xu, Qian Q" <qian.q.xu@intel.com>]

As far as I know, L2FWD only uses 1 core for all RX/TX, for all queues, but for ip_pipeline, you may use more cores. 
A simple question, are you using 1core in ip_pipeline or l3fwd test? 

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Royce Niu
> Sent: Thursday, December 22, 2016 9:36 PM
> To: Richardson, Bruce <bruce.richardson@intel.com>
> Cc: Royce Niu <royceniu@gmail.com>; dev@dpdk.org; Dumitrescu, Cristian
> <cristian.dumitrescu@intel.com>
> Subject: Re: [dpdk-dev] Why IP_PIPELINE is faster than L2FWD
> 
> 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@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@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