Re: [dpdk-dev] [PATCH] examples/l3fwd: change mq-mode on single queue devices

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, May 12, 2021 at 09:43:57PM +0300, Medvedkin, Vladimir wrote:
> Hi Bruce,
> 
> On 12/05/2021 19:32, Bruce Richardson wrote:
> > On Mon, May 10, 2021 at 06:53:19PM +0200, Heinrich Kuhn wrote:
> > > From: "Chaoyong.He" <chaoyong.he@corigine.com>
> > > 
> > > Set the Rx multi-queue mode to NONE when configuring a port that is
> > > associated with hardware that only supports a single Rx queue.
> > > 
> > > Signed-off-by: Chaoyong He <chaoyong.he@corigine.com>
> > > Signed-off-by: Heinrich Kuhn <heinrich.kuhn@netronome.com>
> > > Signed-off-by: Simon Horman <simon.horman@netronome.com>
> > > ---
> > >   examples/l3fwd/main.c | 4 ++++
> > >   1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
> > > index bb49e5faf..87b638ac0 100644
> > > --- a/examples/l3fwd/main.c
> > > +++ b/examples/l3fwd/main.c
> > > @@ -953,6 +953,10 @@ l3fwd_poll_resource_setup(void)
> > >   		local_port_conf.rx_adv_conf.rss_conf.rss_hf &=
> > >   			dev_info.flow_type_rss_offloads;
> > > +
> > > +		if (dev_info.max_rx_queues == 1)
> > > +			local_port_conf.rxmode.mq_mode = ETH_MQ_RX_NONE;
> > > +
> > 
> > While it makes sense to do this when the port only supports a single queue,
> > would it not also make sense to do this when the requested queues are 1
> > too?
> > 
> > Adding some lookup library maintainers on CC - I assume that the RSS value
> > is not actually used for lookup anywhere in l3fwd.
> > 
> 
> As far as I can see the rss hash value is not used anywhere in l3fwd. In
> LPM/FIB this is not required at all, in EM CRC or Jenkins hash is used.
>
That's what I thought from looking at the code too. Since this is not
really a bug fix, I think it can be pushed till 21.08.

With or without the change I suggest above:
Acked-by: Bruce Richardson <bruce.richardson@intel.com>