Re: [PATCH v3 4/5] testpmd: handle all rxqs in rss setup

["Nélio Laranjeiro" <nelio.laranjeiro@6wind.com>]

Hi Pablo,

On Mon, Jun 27, 2016 at 10:36:38PM +0000, De Lara Guarch, Pablo wrote:
> Hi Nelio,
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Nélio Laranjeiro
> > Sent: Monday, June 27, 2016 3:24 PM
> > To: Wang, Zhihong
> > Cc: dev@dpdk.org; Ananyev, Konstantin; Richardson, Bruce; De Lara Guarch,
> > Pablo; thomas.monjalon@6wind.com
> > Subject: Re: [dpdk-dev] [PATCH v3 4/5] testpmd: handle all rxqs in rss setup
> > 
> > On Tue, Jun 14, 2016 at 07:08:05PM -0400, Zhihong Wang wrote:
> > > This patch removes constraints in rxq handling when multiqueue is enabled
> > > to handle all the rxqs.
> > >
> > > Current testpmd forces a dedicated core for each rxq, some rxqs may be
> > > ignored when core number is less than rxq number, and that causes
> > confusion
> > > and inconvenience.
> > >
> > > One example: One Red Hat engineer was doing multiqueue test, there're 2
> > > ports in guest each with 4 queues, and testpmd was used as the forwarding
> > > engine in guest, as usual he used 1 core for forwarding, as a results he
> > > only saw traffic from port 0 queue 0 to port 1 queue 0, then a lot of
> > > emails and quite some time are spent to root cause it, and of course it's
> > > caused by this unreasonable testpmd behavior.
> > >
> > > Moreover, even if we understand this behavior, if we want to test the
> > > above case, we still need 8 cores for a single guest to poll all the
> > > rxqs, obviously this is too expensive.
> > >
> > > We met quite a lot cases like this, one recent example:
> > > http://openvswitch.org/pipermail/dev/2016-June/072110.html
> > >
> > >
> > > Signed-off-by: Zhihong Wang <zhihong.wang@intel.com>
> > > ---
> > >  app/test-pmd/config.c | 8 +-------
> > >  1 file changed, 1 insertion(+), 7 deletions(-)
> > >
> > > diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
> > > index ede7c78..4719a08 100644
> > > --- a/app/test-pmd/config.c
> > > +++ b/app/test-pmd/config.c
> > > @@ -1199,19 +1199,13 @@ rss_fwd_config_setup(void)
> > >  	cur_fwd_config.nb_fwd_ports = nb_fwd_ports;
> > >  	cur_fwd_config.nb_fwd_streams =
> > >  		(streamid_t) (nb_q * cur_fwd_config.nb_fwd_ports);
> > > -	if (cur_fwd_config.nb_fwd_streams > cur_fwd_config.nb_fwd_lcores)
> > > -		cur_fwd_config.nb_fwd_streams =
> > > -			(streamid_t)cur_fwd_config.nb_fwd_lcores;
> > > -	else
> > > -		cur_fwd_config.nb_fwd_lcores =
> > > -			(lcoreid_t)cur_fwd_config.nb_fwd_streams;
> > >
> > >  	/* reinitialize forwarding streams */
> > >  	init_fwd_streams();
> > >
> > >  	setup_fwd_config_of_each_lcore(&cur_fwd_config);
> > >  	rxp = 0; rxq = 0;
> > > -	for (lc_id = 0; lc_id < cur_fwd_config.nb_fwd_lcores; lc_id++) {
> > > +	for (lc_id = 0; lc_id < cur_fwd_config.nb_fwd_streams; lc_id++) {
> > >  		struct fwd_stream *fs;
> > >
> > >  		fs = fwd_streams[lc_id];
> > > --
> > > 2.5.0
> > 
> > Hi Zhihong,
> > 
> > It seems this commits introduce a bug in pkt_burst_transmit(), this only
> > occurs when the number of cores present in the coremask is greater than
> > the number of queues i.e. coremask=0xffe --txq=4 --rxq=4.
> > 
> >   Port 0 Link Up - speed 40000 Mbps - full-duplex
> >   Port 1 Link Up - speed 40000 Mbps - full-duplex
> >   Done
> >   testpmd> start tx_first
> >     io packet forwarding - CRC stripping disabled - packets/burst=64
> >     nb forwarding cores=10 - nb forwarding ports=2
> >     RX queues=4 - RX desc=256 - RX free threshold=0
> >     RX threshold registers: pthresh=0 hthresh=0 wthresh=0
> >     TX queues=4 - TX desc=256 - TX free threshold=0
> >     TX threshold registers: pthresh=0 hthresh=0 wthresh=0
> >     TX RS bit threshold=0 - TXQ flags=0x0
> >   Segmentation fault (core dumped)
> > 
> > 
> > If I start testpmd with a coremask with at most as many cores as queues,
> > everything works well (i.e. coremask=0xff0, or 0xf00).
> > 
> > Are you able to reproduce the same issue?
> > Note: It only occurs on dpdk/master branch (commit f2bb7ae1d204).
> 
> Thanks for reporting this. I was able to reproduce this issue and
> sent a patch that should fix it. Could you verify it?
> http://dpdk.org/dev/patchwork/patch/14430/


I have tested it, it works, I will add a test report on the
corresponding email.

Thanks
> 
> 
> Thanks
> Pablo
> > 
> > Regards,

-- 
Nélio Laranjeiro
6WIND