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

["Rong, Leyi" <leyi.rong@intel.com>]

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Thursday, March 25, 2021 1:23 AM
> To: Jerin Jacob <jerinjacobk@gmail.com>; David Marchand
> <david.marchand@redhat.com>; Rong, Leyi <leyi.rong@intel.com>
> Cc: dev@dpdk.org; Zhang, Qi Z <qi.z.zhang@intel.com>; Richardson, Bruce
> <bruce.richardson@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>
> Subject: Re: [dpdk-dev] [PATCH] examples/l3fwd: enable multiple Tx queues on
> a lcore
> 
> 05/11/2020 10:24, Rong, Leyi:
> > From: Jerin Jacob <jerinjacobk@gmail.com>
> > > On Wed, Nov 4, 2020 at 2:34 PM Rong, Leyi <leyi.rong@intel.com> wrote:
> > > > From: David Marchand <david.marchand@redhat.com>
> > > > > On Wed, Nov 4, 2020 at 9:34 AM Rong, Leyi <leyi.rong@intel.com>
> wrote:
> > > > > > 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?
> > > >
> > > > 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@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?
> 
> Thank you Jerin for providing some info missing in the description of the patch.
> 
> > Hi Jacob,
> >
> > Total queues number equals to queues per port multiply port number.
> > Just take #l3fwd -l 5,6 -n 6 -- -p 0x3 --config
> > '(0,0,5),(0,1,5),(1,0,6),(1,1,6)' as example, With this patch appied,
> > totally 2x2=4 tx queues can be polled, while only
> > 1x2=2 tx queues can be used before.
> 
> It does not reply above question with N x M.
> 
> > > Does this patch has any regression in case the NIC queues able to
> > > cope up with the throughput limit from CPU.
> >
> > Regression test relevant with l3fwd passed with this patch, no obvious
> > result drop on other cases.
> 
> It does not reply the general question for all drivers you did not test.
> 
> As you probably noticed, this patch is blocked for months because it is not
> properly explained.
> 

Hi Thomas,

This patch can be abandoned after synced with Konstantin months ago. And update the state to superseded on patchwork, Thanks!