On 4/4/2024 2:26 PM, Konstantin Ananyev wrote: > > >>>> -----Original Message----- >>>> From: Stephen Hemminger <step...@networkplumber.org> >>>> Sent: Tuesday, January 9, 2024 11:07 PM >>>> To: Konstantin Ananyev <konstantin.anan...@huawei.com> >>>> Cc: dev@dpdk.org; arshdeep.k...@intel.com; Gowda, Sandesh >>>> <sandesh.go...@intel.com>; Reshma Pattan >>>> <reshma.pat...@intel.com> >>>> Subject: Re: Issues around packet capture when secondary process is doing >>>> rx/tx >>>> >>>> On Mon, 8 Jan 2024 15:13:25 +0000 >>>> Konstantin Ananyev <konstantin.anan...@huawei.com> wrote: >>>> >>>>>> I have been looking at a problem reported by Sandesh >>>>>> where packet capture does not work if rx/tx burst is done in secondary >>>>>> process. >>>>>> >>>>>> The root cause is that existing rx/tx callback model just doesn't work >>>>>> unless the process doing the rx/tx burst calls is the same one that >>>>>> registered the callbacks. >>>>>> >>>>>> An example sequence would be: >>>>>> 1. dumpcap (or pdump) as secondary tells pdump in primary to register >>>>>> callback >>>>>> 2. secondary process calls rx_burst. >>>>>> 3. rx_burst sees the callback but it has pointer pdump_rx which is not >>>>>> necessarily >>>>>> at same location in primary and secondary process. >>>>>> 4. indirect function call in secondary to bad location likely causes >>>>>> crash. >>>>> >>>>> As I remember, RX/TX callbacks were never intended to work over multiple >>>>> processes. >>>>> Right now RX/TX callbacks are private for the process, different process >>>>> simply should not >>>>> see/execute them. >>>>> I.E. it callbacks list is part of 'struct rte_eth_dev' itself, not the >>>>> rte_eth_dev.data that is shared >>>>> between processes. >>>>> It should be normal, wehn for the same port/queue you will end-up with >>>>> different list of callbacks >>>>> for different processes. >>>>> So, unless I am missing something, I don't see how we can end-up with 3) >>>>> and 4) from above: >>>>> From my understanding secondary process will never see/call primary's >>>>> callbacks. >>>>> >>>>> About pdump itself, it was a while when I looked at it last time, but as >>>>> I remember to start it to work, >>>>> server process has to call rte_pdump_init() which in terns register >>>>> PDUMP_MP handler. >>>>> I suppose for the secondary process to act as a 'pdump server' it needs >>>>> to call rte_pdump_init() itself, >>>>> though I am not sure such option is supported right now. >>>>> >>>> >>>> Did some more tests with modified testpmd, and reached some conclusions: >>>> >>>> The logical interface would be to allow rte_pdump_init() to be called by >>>> the process that would be using rx/tx burst API's. >>>> >>>> This doesn't work as it should because the multi-process socket API >>>> assumes that the it only runs the server in primary. The secondary >>>> can start its own MP thread, but it won't work: >>>> >>>> Primary EAL: Multi-process socket /var/run/dpdk/rte/mp_socket >>>> Secondary: EAL: Multi-process socket >>>> /var/run/dpdk/rte/mp_socket_6057_1ccd4157fd5 >>>> >>>> The problem is when client (pdump or dumpcap) tries to run, it uses the >>>> mp_socket >>>> in the primary which causes: EAL: Cannot find action: mp_pdump >>>> >>>> Looks like the whole MP socket mechanism is just not up to this. >>>> >>>> Maybe pdump needs to have its own socket and control thread? >>>> Or MP socket needs to have some multicast fanout to all secondaries? >>> >>> Might be we can do something simpler: pass to pdump_enable(), where we want >>> to enable it: >>> on primary (remote_ process or secondary (local) process? >>> And then for primary send a message over MP socket (as we doing now), and >>> for secondary (itself) >>> just do actual pdump enablement on it's own (install callbacks, etc.). >>> Yes, in that way, one secondary would not be able to enable/idable pdump on >>> another secondary, >>> only on itself, but might be it is not needed? >>> >>> >> >> How secondary, lets say testpmd secondary, install callbacks without >> getting 'mp' & 'ring' info from pdump secondary process? > > Please see my comment above (I copied it here too): >> Yes, in that way, one secondary would not be able to enable/disable pdump on >> another secondary, only on itself, but might be it is not needed? >
I saw it Konstantin, but it wasn't clear to me what you are suggesting, that is why I am asking more. Do you suggest when testpmd run as secondary process and doing forwarding, it should do the tasks of pdump itself and we don't use pdump at all?
