[dpdk-dev] [PATCH] examples/l3fwd: enable multiple Tx queues on a lcore

[Jerin Jacob]

On Wed, Nov 4, 2020 at 2:34 PM Rong, Leyi <leyi.rong at intel.com> wrote:
>
>
> > -----Original Message-----
> > From: David Marchand <david.marchand at redhat.com>
> > Sent: Wednesday, November 4, 2020 4:43 PM
> > To: Rong, Leyi <leyi.rong at intel.com>
> > Cc: Zhang, Qi Z <qi.z.zhang at intel.com>; dev <dev at dpdk.org>
> > Subject: Re: [PATCH] examples/l3fwd: enable multiple Tx queues on a lcore
> >
> > On Wed, Nov 4, 2020 at 9:34 AM Rong, Leyi <leyi.rong at intel.com> wrote:
> > > > -----Original Message-----
> > > > From: David Marchand <david.marchand at redhat.com>
> > > > Sent: Wednesday, November 4, 2020 4:14 PM
> > > > To: Rong, Leyi <leyi.rong at intel.com>
> > > > Cc: Zhang, Qi Z <qi.z.zhang at intel.com>; dev <dev at dpdk.org>
> > > > Subject: Re: [PATCH] examples/l3fwd: enable multiple Tx queues on a
> > > > lcore
> > > >
> > > > If I count well, this is the v3 of the patch.
> > > > Please version your patches.
> > >
> > > The previous versions are set to superseded. As nothing changes with
> > > content on those versions, can start from this version?
> >
> > The commitlog changes even if the code itself did not change, so this is a
> > different patch.
> > Different patches mean different versions.
> > This shows that some work happened since the v1 submission.
> >
>
> Agreed.
> >
> > > As there always has thoughput limit for per queue, on some performance
> > > test case by using l3fwd, the result will limited by the per queue
> > > thoughput limit. With multiple Tx queue enabled, the per queue thoughput
> > limit can be eliminated if the CPU core is not the bottleneck.
> >
> > Ah interesting.
> > Which nic has such limitations?
> > How much of an improvement can be expected from this?
> >
> >
> > --
> > David Marchand
>
> The initial found was on XXV710 25Gb NIC, but suppose such issue can happen on more NICs
> as the high-end CPU per core boundary is higher than many NICs(except 100Gb and above) per queue performance boundary.
> The improvement can be about 1.8X with that case at 1t2q.

As far as I understand, the Current l3fwd Tx queue creation is like this:
If the app has N cores and M ports then l3fwd creates, N x M Tx queues in total,
What will be new values based on this patch?

Does this patch has any regression in case the NIC queues able to cope
up with the throughput limit
from CPU.


>
> Leyi
>