> -----Original Message----- > From: Ananyev, Konstantin <konstantin.anan...@intel.com> > Sent: Thursday, August 8, 2019 10:24 PM > To: Jerin Jacob Kollanukkaran <jer...@marvell.com>; Pavan Nikhilesh > Bhagavatula <pbhagavat...@marvell.com>; step...@networkplumber.org; > arybche...@solarflare.com; hemant.agra...@nxp.com; > tho...@monjalon.net; Yigit, Ferruh <ferruh.yi...@intel.com>; Richardson, > Bruce <bruce.richard...@intel.com>; Neil Horman > <nhor...@tuxdriver.com>; Mcnamara, John <john.mcnam...@intel.com>; > Kovacevic, Marko <marko.kovace...@intel.com> > Cc: dev@dpdk.org > Subject: [EXT] RE: [dpdk-dev] [patch v3] doc: announce API change in ethdev > offload flags > > > > Since application has two knobs rte_eth_dev_get_supported_ptypes() > > > > and DEV_RX_OFFLOAD_PTYPE. We may not need to new ol_flags for > this > > > change. Right? > > > > i.e if application sets the DEV_RX_OFFLOAD_PTYPE, The application > > > > will get the parsed ptypes by the driver(= > > > rte_eth_dev_get_supported_ptypes()). > > > > So there is no scope ambiguity. Right? > > > > > > I still think there is: > > > Imagine user has 2 eth devices, one does support > > > DEV_RX_OFFLOAD_PTYPE, second doesn't. Now he has a mix of packets > > > from both devices, that you want t process. > > > How would he figure out for which of them ptype values are valid, > > > and for each are not? > > > Trace back from what port he has received them? > > > Not very convenient, and not always possible. > > > > I thought so. But in that case, application can always set > > DEV_RX_OFFLOAD_PTYPE Flags for all the ethdev ports. Right? Rather > > having any complicated ol_flags or port based parsing. If limit the > _contract_ to following, we are good. Right? > > # when DEV_RX_OFFLOAD_PTYPE is set, mbuf.packet_type will be valid > and > > mbuf.packet_type will have parsed packet type > > Yes sure in principle user can calculate smallest common subset of RX > offloads supported by all devs in the system and use only them. > Then he can use some global value for ol_flags that will be setup at > initialization time, instead of checking ol_flags for every mbuf. > Though inside DPDK we don't use that method for other offloads (cksum, > vlan, rss). > Why we should do different here?
I agree. We don't need to. > Again how to deal with hot-plugged devices with such approach? > > > > > or the negative offload(This contract is pretty clear, I don't think > > any ambiguity at all) # when DEV_RX_OFFLOAD_NO_PTYPE(something > > similar) is set, mbuf.packet_type will be invalid. > > > > > I think we need either to introduce new ol_flag value (as we usually > > > do for other RX offloads), or force PMD to always set ptype value. > > > > Setting new ol_flag value may effect performance for existing drivers > > which don't planning to use this offload > > If the driver doesn't support DEV_RX_OFFLOAD_PTYPE, it wouldn't need to > set anything (neither ol_flags, neither packet_type). Yes > > > and it complicates the > > application to have additional check based on ol_flag. If you see any > > corner case with above section, > > > > How about just setting as ptype as 0 incase it is not parsed by driver. > > As I said above - ok by me. > AFAIK, this is current behavior, so no changes in PMD will be required. > > > Actual lookup is the costly one, writing 0 to pytpe is not costly as > > there are plenty of writes in Rx and it will be write merged(No CPU > > stall) > > Yes packet_type is at first 64B, so shouldn't cause any extra overhead. > > > > > I did not get the complete picture of > > "rte_eth_dev_set_supported_ptypes(uint16_t port_id, uint32_t > ptype_mask); instead of DEV_RX_OFFLOAD_PTYPE? scheme", Does it help? > > I thought about it as just a different way to disable(/limit) requested by > user > PTYPE support. > If let say user is not interested in ptype information at all, he can ask PMD > to > just always set ptype value to 0: > rte_eth_dev_set_supported_ptypes(port, RTE_PTYPE_UNKNOWN); > > if he is interested just in L2/L3 layer info, he can ask PMD to provide ptype > information only for L2/L3: > rte_eth_dev_set_supported_ptypes(port, RTE_PTYPE_L2_MASK | > RTE_PTYPE_L3_MASK); > > Or to enable all supported by PMD ptypes: > rte_eth_dev_set_supported_ptypes(port, UINT32_MAX) The API looks good to me. We need to document the rte_eth_dev_set_supported_ptypes() must be called when device is in stop state to allow PMD do slow path configuration. To summarize: Two options to control PTYPE lookup: Option 1: - If DEV_RX_OFFLOAD_PTYPE set, PMD returns mbuf->packet_type with rte_eth_dev_get_supported_ptypes() - If DEV_RX_OFFLOAD_PTYPE is not set, PMD still can return mbuf->packet_type with rte_eth_dev_get_supported_ptypes() But if PMD can do some optimization, it can avoid ptype lookup and return mbuf->packet_type as zero. Option 2: - Introduce rte_eth_dev_set_supported_ptypes(port, needed_ptypes). I think, rte_eth_dev_set_supported_ptypes() is better option As Konstantain suggested to have selective control of ptype parsing by PMD at the cost of adding new API. I think, we can avoid breaking exiting application by, If rte_eth_dev_set_supported_ptypes() is not called, PMD must return mbuf->packet_type with rte_eth_dev_get_supported_ptypes(). If rte_eth_dev_set_supported_ptypes() and successful, PMD must return mbuf->packet_type with rte_eth_dev_set_supported_ptypes() If there no objection to this API, We can send updated deprecation notice. >
