Re: [dpdk-dev] [PATCH 2/3] app/testpmd: remove forwarding config from parsing Rx and Tx

["Li, Xiaoyun" <xiaoyun.li@intel.com>]

> -----Original Message-----
> From: oulijun <oulijun@huawei.com>
> Sent: Wednesday, March 24, 2021 09:01
> To: Li, Xiaoyun <xiaoyun.li@intel.com>; Yigit, Ferruh <ferruh.yigit@intel.com>
> Cc: dev@dpdk.org; linuxarm@openeuler.org
> Subject: Re: [PATCH 2/3] app/testpmd: remove forwarding config from parsing
> Rx and Tx
> 
> 
> 
> 在 2021/3/23 15:50, Li, Xiaoyun 写道:
> > Hi
> >
> >> -----Original Message-----
> >> From: Lijun Ou <oulijun@huawei.com>
> >> Sent: Friday, March 5, 2021 18:22
> >> To: Yigit, Ferruh <ferruh.yigit@intel.com>
> >> Cc: Li, Xiaoyun <xiaoyun.li@intel.com>; dev@dpdk.org;
> >> linuxarm@openeuler.org
> >> Subject: [PATCH 2/3] app/testpmd: remove forwarding config from
> >> parsing Rx and Tx
> >>
> >> From: Huisong Li <lihuisong@huawei.com>
> >>
> >
> > The commit message should be more simple and avoids grammar mistakes.
> >
> All right, I will simply it.
> >> The "fwd_config_setup()" function does release and apply for memory
> >> of forwarding flows, and re-establish these streams when rxq/txq or
> >> rxd/txd is changed. The function is also called by
> >> "start_packet_forwarding()" when user executes "start" cmd.
> >> All changes for rxq/txq or rxd/txd can be updated uniformly when this
> >> command is executed. Therefore, it is a little redundant in the
> "cmd_config_rx_tx_parsed"
> >> function.
> >
> > It's not redundant. This command may configure number of rxq/txq. So the
> fwd streams map may change.
> > Then it's common to check the fwd streams after this command using "show
> config fwd".
> > If you remove this fwd stream update, users can't get the correct new fwd
> streams until they start the traffic.
> > But they may change a lot of things and want to check if the setting is correct
> before they start the traffic.
> >
> Yes, you are right. It's really unfriendly.
> >>
> >> In addition, the forwarding stream under one TC is configured based
> >> on number of queues allocated to TC. And number of queues allocated
> >> to TC is updated after calling  "rte_eth_dev_configure"
> >> again. If the number of queues is reduced after configuring the DCB,
> >> and then, release and apply for stream memory, and reinitialize the
> >> forwarding stream under the DCB mode based on the old TC information.
> >> As a result, null pointer may be accessed.
> >
> > I think you should add "rte_eth_dev_configure " into dcb_fwd_config_setup()
> before rte_eth_dev_get_dcb_info().
> >
> > And the commit message should be similar like the following:
> > Segment fault might happen after configuring queue number to less because
> dcb_fwd_config_setup setup dcb based on old dcb info.
> > And dcb info can only update after rte_eth_dev_configure().
> > So this patch adds rte_eth_dev_configure() before rte_eth_dev_get_dcb_info()
> to get updated dcb info to fix this issue.
> >
> Thank you for your advice. But the above adjustments may still not work for
> some drivers. The mapping between queues and TCs in these drivers is updated
> in the dev_start stage.
> 
> I have an idea. We can move fwd_config_setup() to start_port(), which is called
> by main() and after starting ports This not only solves the segment fault, but also
> does not have the problem you mentioned above. I test it and it is ok.
> 
> What do you think, xiaoyun?

How can you fix the issue I mentioned?
You still need to start port first to see the updated fwd config.
And for those drivers, why does the mapping has to be updated in dev_start stage?
What does it need? Can't it be moved to dev_configure?
> 
> 
> >>
> >> Like:
> >> set nbcore 4
> >> port stop all
> >> port config 0 dcb vt off 4 pfc on
> >> port start all
> >> port stop all
> >> port config all rxq 8
> >> port config all txq 8
> >>
> >> At the moment, a segmentation fault occurs.
> >>
> >> Fixes: ce8d561418d4 ("app/testpmd: add port configuration settings")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> >> Signed-off-by: Lijun Ou <oulijun@huawei.com>
> >> ---
> >> V1->V2:
> >> - use stream instead of flow
> >> ---
> >>   app/test-pmd/cmdline.c | 2 --
> >>   1 file changed, 2 deletions(-)
> >>
> >> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c index
> >> 4df0c32..e316f5c 100644
> >> --- a/app/test-pmd/cmdline.c
> >> +++ b/app/test-pmd/cmdline.c
> >> @@ -1837,8 +1837,6 @@ cmd_config_rx_tx_parsed(void *parsed_result,
> >>   		return;
> >>   	}
> >>
> >> -	fwd_config_setup();
> >> -
> >>   	init_port_config();
> >>
> >>   	cmd_reconfig_device_queue(RTE_PORT_ALL, 1, 1);
> >> --
> >> 2.7.4
> >
> > .
> >