Sat, Sep 23, 2017 at 02:47:20AM CEST, [email protected] wrote: >Hi, Jiri > >On 2017/9/23 0:03, Jiri Pirko wrote: >> Fri, Sep 22, 2017 at 04:11:51PM CEST, [email protected] wrote: >>> Hi, Jiri >>> >>>>> - if (!tc) { >>>>> + if (if_running) { >>>>> + (void)hns3_nic_net_stop(netdev); >>>>> + msleep(100); >>>>> + } >>>>> + >>>>> + ret = (kinfo->dcb_ops && kinfo->dcb_ops->>setup_tc) ? >>>>> + kinfo->dcb_ops->setup_tc(h, tc, prio_tc) : ->EOPNOTSUPP; >>> >>>> This is most odd. Why do you call dcb_ops from >ndo_setup_tc callback? >>>> Why are you mixing this together? prio->tc mapping >can be done >>>> directly in dcbnl >>> >>> Here is what we do in dcb_ops->setup_tc: >>> Firstly, if current tc num is different from the tc num >>> that user provide, then we setup the queues for each >>> tc. >>> >>> Secondly, we tell hardware the pri to tc mapping that >>> the stack is using. In rx direction, our hardware need >>> that mapping to put different packet into different tc' >>> queues according to the priority of the packet, then >>> rss decides which specific queue in the tc should the >>> packet goto. >>> >>> By mixing, I suppose you meant why we need the >>> pri to tc infomation? >> >> by mixing, I mean what I wrote. You are calling dcb_ops callback from >> ndo_setup_tc callback. So you are mixing DCBNL subsystem and TC >> subsystem. Why? Why do you need sch_mqprio? Why DCBNL is not enough for >> all? > >When using lldptool, dcbnl is involved. > >But when using tc qdisc, dcbbl is not involved, below is the a few key >call graph in the kernel when tc qdisc cmd is executed. > >cmd: >tc qdisc add dev eth0 root handle 1:0 mqprio num_tc 4 map 1 2 3 3 1 3 1 1 hw 1 > >call graph: >rtnetlink_rcv_msg -> tc_modify_qdisc -> qdisc_create -> mqprio_init -> >hns3_nic_setup_tc > >When hns3_nic_setup_tc is called, we need to know how many tc num and >prio_tc mapping from the tc_mqprio_qopt which is provided in the paramter >in the ndo_setup_tc function, and dcb_ops is the our hardware specific >method to setup the tc related parameter to the hardware, so this is why >we call dcb_ops callback in ndo_setup_tc callback. > >I hope this will answer your question, thanks for your time.
Okay. I understand that you have a usecase for mqprio mapping offload without lldptool being involved. Ok. I believe it is wrong to call dcb_ops from tc callback. You should have a generic layer inside the driver and call it from both dcb_ops and tc callbacks. Also, what happens If I run lldptool concurrently with mqprio? Who wins and is going to configure the mapping? > >> >> >> >>> I hope I did not misunderstand your question, thanks >>> for your time reviewing. >> >> . >> >
