[dpdk-dev] [PATCH v3 4/5] testpmd: handle all rxqs in rss setup

De Lara Guarch, Pablo pablo.de.lara.guarch at intel.com
Tue Jun 28 00:36:38 CEST 2016


Hi Nelio,

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Nélio Laranjeiro
> Sent: Monday, June 27, 2016 3:24 PM
> To: Wang, Zhihong
> Cc: dev at dpdk.org; Ananyev, Konstantin; Richardson, Bruce; De Lara Guarch,
> Pablo; thomas.monjalon at 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 at 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/


Thanks
Pablo
> 
> Regards,
> 
> --
> Nélio Laranjeiro
> 6WIND


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