On 11/13/2018 6:27 PM, Zhang, Qi Z wrote: > First, apologies to make this in rush since I was somehow under pressure to > make pdump works in 18.11. > I agree there is lot of things need to improve, but the strategy here is to > make it work quietly and not break anything else :) > add some comments inline. > >> -----Original Message----- >> From: Thomas Monjalon [mailto:tho...@monjalon.net] >> Sent: Tuesday, November 13, 2018 9:15 AM >> To: Yigit, Ferruh <ferruh.yi...@intel.com>; Zhang, Qi Z >> <qi.z.zh...@intel.com> >> Cc: dev@dpdk.org; Lin, Xueqin <xueqin....@intel.com> >> Subject: Re: [PATCH v2] net/pcap: enable data path on secondary >> >> Just a quick comment: >> There are probably some ideas to take from what was done for tap. > >> >> >> 13/11/2018 17:56, Ferruh Yigit: >>> On 11/12/2018 4:51 PM, Qi Zhang wrote: >>>> Private vdev on secondary is never supported by the new shared >>>> device mode but pdump still relies on a private pcap PMD on secondary. >>>> The patch enables pcap PMD's data path on secondary so that pdump >>>> can work as usual. >>> >>> It would be great if you described the problem a little more. >>> >>> Private vdev was the way previously, when pdump developed, now with >>> shared device mode on virtual devices, pcap data path in secondary is not >> working. >>> >>> What exactly not working is (please correct me if I am wrong): >>> When secondary adds a virtual device, related data transferred to >>> primary and primary creates the device and shares device back with >> secondary. >>> When pcap device created in primary, pcap handlers (pointers) are >>> process local and they are not valid for secondary process. This breaks >> secondary. >>> >>> So we can't directly share the pcap handlers, but need to create a new >>> set of handlers for secondary, that is what you are doing in this >>> patch, although I have some comments, please check below. >>> >>> Since there is single storage for pcap handlers that primary and >>> secondary shares and they can't share the handlers, you can't make >>> both primary and secondary data path work. Also freeing handlers is >>> another concern. What is needed is `rte_eth_dev->process_private` which >> has been added in this release. > > You are right, we should prevent handler be opened in primary be corrupted > during probe at secondary. > Now, I see this problem in pcap , as an example: > internals->tx_queue[i].dumper/pcap is shared but will be overwritten at > secondary, we should fix them by use process_private, > >>> >>>> >>>> Signed-off-by: Qi Zhang <qi.z.zh...@intel.com> >>>> Tested-by: Yufeng Mo <yufengx...@intel.com> >>> >>> <...> >>> >>>> @@ -934,6 +935,10 @@ pmd_init_internals(struct rte_vdev_device >> *vdev, >>>> */ >>>> (*eth_dev)->dev_ops = &ops; >>>> >>>> + /* store a copy of devargs for secondary process */ >>>> + strlcpy(internals->devargs, rte_vdev_device_args(vdev), >>>> + ETH_PCAP_ARG_MAXLEN); >>> >>> Why we need to cover this in PMD level? >>> >>> Why secondary probe isn't getting devargs? Can't we fix this in eal level? >>> It can be OK to workaround in the PMD taking account of the time of >>> the release, but for long term I think this should be fixed in eal. > > Yes this is the workaround for quick fix. > Ideally secondary process should not take care of devargs, it just attach. > And it's better to only parse devargs on one process ( primary process), the > parsed result could be stored to intermediate result in shared > memory,(examples, internal->nb_rx_queue_required) so secondary process don't > need to parse it again. >>> >>> <...> >>> >>>> @@ -1122,23 +1126,37 @@ pmd_pcap_probe(struct rte_vdev_device >> *dev) >>>> start_cycles = rte_get_timer_cycles(); >>>> hz = rte_get_timer_hz(); >>>> >>>> - if (rte_eal_process_type() == RTE_PROC_SECONDARY) { >>>> + if (rte_eal_process_type() == RTE_PROC_PRIMARY) { >>>> + kvlist = rte_kvargs_parse(rte_vdev_device_args(dev), >>>> + valid_arguments); >>>> + if (kvlist == NULL) >>>> + return -EINVAL; >>>> + if (rte_kvargs_count(kvlist, ETH_PCAP_IFACE_ARG) == 1) >>>> + nb_rx_queue = 1; >>>> + else >>>> + nb_rx_queue = >>>> + rte_kvargs_count(kvlist, >>>> + ETH_PCAP_RX_PCAP_ARG) ? 1 : 0; >>>> + nb_tx_queue = 1; >>> >>> This part is wrong. pcap pmd supports multi queue, you can't hardcode >>> the number of queues. Also for Tx why it ignores `rx_iface` argument? >>> This is just hacking the driver for a specific use case breaking others. > > Previously the nb_tx_queue and nb_rx_queue is decided by pcaps.num_of_queue > and dumpers.num_of_queues. > I just can't figure out a way that we can have more than 1 queue during > probe, look at below code. > > If ETH_PCAP_IFACE_ARG > > pcaps.num_of_queue = 1; > dumpers.num_of_queue = 1; > > else > is_rx_pcap = rte_kvargs_count(kvlist, ETH_PCAP_RX_PCAP_ARG) ? 1 : 0; > pcaps.num_of_queue = 0; > if (is_rx_pcap) { > ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_PCAP_ARG, > &open_rx_pcap, &pcaps); > > // pcaps.num_of_queue = 1; > } else { > ret = rte_kvargs_process(kvlist, NULL, > &rx_iface_args_process, &pcaps); > // pcaps.num_of_queue = 0; > } > > is_tx_pcap = rte_kvargs_count(kvlist, ETH_PCAP_TX_PCAP_ARG) ? 1 > : 0; > dumpers.num_of_queue = 0; > > if (is_tx_pcap) > ret = rte_kvargs_process(kvlist, ETH_PCAP_TX_PCAP_ARG, > &open_tx_pcap, &dumpers); > // dumpers.num_of_queue = 1 > else > ret = rte_kvargs_process(kvlist, ETH_PCAP_TX_IFACE_ARG, > &open_tx_iface, &dumpers); > // dumpers.num_of_queue = 1 > > That's the same logic I applied, did I missed something, would you explain > more for this?
ETH_PCAP_IFACE_ARG is "iface=xxx" usage, both Rx and Tx use the same interface, because of implementation limitation it only supports 1 queue. rx_pcap, rx_iface, rx_iface_in supports multiple queues, by providing them multiple time. Like "rx_pcap=q1.pcap,rx_pcap=q2.pcap,rx_pcap=q3.pcap" will create 3 Rx queues each having their own .pcap file. Same is valid for Tx. rte_kvargs_process() calls callback function per argument provided, so if an argument provided multiple times, it will call same callback multiple times, that is why 'num_of_queue' increased in callback functions. In high-level, pmd_pcap_probe() first parses the arguments and creates pcap handlers based on arguments, later as a last thing creates ethdev using these information. I am for keeping this logic, doing something different for secondary can cause issues in edge cases not obvious at first look. > > Thanks > Qi > >>> >>>> + ret = pmd_init_internals(dev, nb_rx_queue, >>>> + nb_tx_queue, ð_dev); >>> >>> I think it is not required to move pmd_init_internals() here. >>> This can be done simpler, I will send a draft patch as a reply to this >>> mail for possible solution. >>> But again that can't be final solution, we need to use >>> `process_private` >>> >>> <...> >>> >> >> >> >> >
