From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 28846A04DC; Mon, 19 Oct 2020 20:01:39 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 70D11E2EE; Mon, 19 Oct 2020 20:01:37 +0200 (CEST) Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id 72325A550 for ; Mon, 19 Oct 2020 20:01:34 +0200 (CEST) IronPort-SDR: /yaNWsyGId8+11ofihMbtKIsyLkdkh8zlT9pMHNDHVsXjzMgBWXKjEzCbXaDG8cmfg6ZB+XaE8 bAheyCDWReWQ== X-IronPort-AV: E=McAfee;i="6000,8403,9779"; a="154014839" X-IronPort-AV: E=Sophos;i="5.77,395,1596524400"; d="scan'208";a="154014839" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2020 11:01:30 -0700 IronPort-SDR: OxryymCy7ygwUjyUH7XtCj+NWhjTDRm26IEZOsIsnfIyuLc+9mwJDIJuQEcI2UJv7pxFlTpwji a5Hy7H5Tzobw== X-IronPort-AV: E=Sophos;i="5.77,395,1596524400"; d="scan'208";a="347525695" Received: from fyigit-mobl1.ger.corp.intel.com (HELO [10.252.19.15]) ([10.252.19.15]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Oct 2020 11:01:27 -0700 To: "Ananyev, Konstantin" , "Yang, SteveX" , "Zhang, Qi Z" , "dev@dpdk.org" Cc: "Zhao1, Wei" , "Guo, Jia" , "Yang, Qiming" , "Wu, Jingjing" , "Xing, Beilei" , "Stokes, Ian" References: <20200923040909.73418-1-stevex.yang@intel.com> <20200928065541.7520-1-stevex.yang@intel.com> <20200928065541.7520-4-stevex.yang@intel.com> <8459e979b76c43cdbd5a9fbd809f9b00@intel.com> <6ad9e3ec00194e31891d97849135655c@intel.com> <7704b7ce95fd4db2a9c6a8a33c3f0805@intel.com> <77ac2293-e532-e702-2370-c07cdd957c57@intel.com> <483bd509-82b9-9724-d28c-c517ef091e0c@intel.com> From: Ferruh Yigit Message-ID: Date: Mon, 19 Oct 2020 19:01:21 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH v4 3/5] net/ice: fix max mtu size packets with vlan tag cannot be received by default X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 10/19/2020 3:28 PM, Ananyev, Konstantin wrote: > >> >>>>>>>>>>>> >>>>>>>>>>>> testpmd will initialize default max packet length to 1518 which >>>>>>>>>>>> doesn't include vlan tag size in ether overheader. Once, send the >>>>>>>>>>>> max mtu length packet with vlan tag, the max packet length will >>>>>>>>>>>> exceed 1518 that will cause packets dropped directly from NIC hw >>>>>>>> side. >>>>>>>>>>>> >>>>>>>>>>>> ice can support dual vlan tags that need more 8 bytes for max >>>>>>>>>>>> packet size, so, configures the correct max packet size in >>>>>>>>>>>> dev_config >>>>>>>>> ops. >>>>>>>>>>>> >>>>>>>>>>>> Fixes: 50cc9d2a6e9d ("net/ice: fix max frame size") >>>>>>>>>>>> >>>>>>>>>>>> Signed-off-by: SteveX Yang >>>>>>>>>>>> --- >>>>>>>>>>>> drivers/net/ice/ice_ethdev.c | 11 +++++++++++ >>>>>>>>>>>> 1 file changed, 11 insertions(+) >>>>>>>>>>>> >>>>>>>>>>>> diff --git a/drivers/net/ice/ice_ethdev.c >>>>>>>>>>>> b/drivers/net/ice/ice_ethdev.c index >>>>>>>>>>>> cfd357b05..6b7098444 100644 >>>>>>>>>>>> --- a/drivers/net/ice/ice_ethdev.c >>>>>>>>>>>> +++ b/drivers/net/ice/ice_ethdev.c >>>>>>>>>>>> @@ -3146,6 +3146,7 @@ ice_dev_configure(struct rte_eth_dev >>>>>> *dev) >>>>>>>>>>>> struct ice_adapter *ad = >>>>>>>>>>>> ICE_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private); >>>>>>>>>>>> struct ice_pf *pf = >>>>>>>>>>>> ICE_DEV_PRIVATE_TO_PF(dev->data->dev_private); >>>>>>>>>>>> +uint32_t frame_size = dev->data->mtu + ICE_ETH_OVERHEAD; >>>>>>>>>>>> int ret; >>>>>>>>>>>> >>>>>>>>>>>> /* Initialize to TRUE. If any of Rx queues doesn't meet the @@ >>>>>>>>>>>> -3157,6 >>>>>>>>>>>> +3158,16 @@ ice_dev_configure(struct rte_eth_dev *dev) >>>>>>>>>>>> if (dev->data->dev_conf.rxmode.mq_mode & >>>>>> ETH_MQ_RX_RSS_FLAG) >>>>>>>>>>>> dev->data->dev_conf.rxmode.offloads |= >>>>>>>>> DEV_RX_OFFLOAD_RSS_HASH; >>>>>>>>>>>> >>>>>>>>>>>> +/** >>>>>>>>>>>> + * Considering QinQ packet, max frame size should be equal or >>>>>>>>>>>> + * larger than total size of MTU and Ether overhead. >>>>>>>>>>>> + */ >>>>>>>>>>> >>>>>>>>>>>> +if (frame_size > dev->data->dev_conf.rxmode.max_rx_pkt_len) { >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Why we need this check? >>>>>>>>>>> Can we just call ice_mtu_set directly >>>>>>>>>> >>>>>>>>>> I think that without that check we can silently overwrite provided >>>>>>>>>> by user dev_conf.rxmode.max_rx_pkt_len value. >>>>>>>>> >>>>>>>>> OK, I see >>>>>>>>> >>>>>>>>> But still have one question >>>>>>>>> dev->data->mtu is initialized to 1518 as default , but if >>>>>>>>> dev->data->application set >>>>>>>>> dev_conf.rxmode.max_rx_pkt_len = 1000 in dev_configure. >>>>>>>>> does that mean we will still will set mtu to 1518, is this expected? >>>>>>>>> >>>>>>>> >>>>>>>> max_rx_pkt_len should be larger than mtu at least, so we should raise >>>>>>>> the max_rx_pkt_len (e.g.:1518) to hold expected mtu value (e.g.: 1500). >>>>>>> >>>>>>> Ok, this describe the problem more general and better to replace exist >>>>>> code comment and commit log for easy understanding. >>>>>>> Please send a new version for reword >>>>>>> >>>>>> >>>>>> I didn't really get this set. >>>>>> >>>>>> Application explicitly sets 'max_rx_pkt_len' to '1518', and a frame bigger than >>>>>> this size is dropped. >>>>> >>>>> Sure, it is normal case for dropping oversize data. >>>>> >>>>>> Isn't this what should be, why we are trying to overwrite user configuration >>>>>> in PMD to prevent this? >>>>>> >>>>> >>>>> But it is a confliction that application/user sets mtu & max_rx_pkt_len at the same time. >>>>> This fix will make a decision when confliction occurred. >>>>> MTU value will come from user operation (e.g.: port config mtu 0 1500) directly, >>>>> so, the max_rx_pkt_len will resize itself to adapt expected MTU value if its size is smaller than MTU + Ether overhead. >>>>> >>>>>> During eth_dev allocation, mtu set to default '1500', by ethdev layer. >>>>>> And testpmd sets 'max_rx_pkt_len' by default to '1518'. >>>>>> I think Qi's concern above is valid, what is user set 'max_rx_pkt_len' to '1000' >>>>>> and mean it? PMD will not honor the user config. >>>>> >>>>> I'm not sure when set 'mtu' to '1500' and 'max_rx_pkt_len' to '1000', what's the behavior expected? >>>>> If still keep the 'max_rx_pkt_len' value, that means the larger 'mtu' will be invalid. >>>>> >>>>>> >>>>>> Why not simply increase the default 'max_rx_pkt_len' in testpmd? >>>>>> >>>>> The default 'max_rx_pkt_len' has been initialized to generical value (1518) and default 'mtu' is '1500' in testpmd, >>>>> But it isn't suitable to those NIC drivers which Ether overhead is larger than 18. (e.g.: ice, i40e) if 'mtu' value is preferable. >>>>> >>>>>> And I guess even better what we need is to tell to the application what the >>>>>> frame overhead PMD accepts. >>>>>> So the application can set proper 'max_rx_pkt_len' value per port for a >>>>>> given/requested MTU value. >>>>>> @Ian, cc'ed, was complaining almost same thing years ago, these PMD >>>>>> overhead macros and 'max_mtu'/'min_mtu' added because of that, perhaps >>>>>> he has a solution now? >>>> >>>> From my perspective the main problem here: >>>> We have 2 different variables for nearly the same thing: >>>> rte_eth_dev_data.mtu and rte_eth_dev_data.dev_conf.max_rx_pkt_len. >>>> and 2 different API to update them: dev_mtu_set() and dev_configure(). >>> >>> According API 'max_rx_pkt_len' is 'Only used if JUMBO_FRAME enabled' >>> Although not sure that is practically what is done for all drivers. >> >> I think most of Intel PMDs use it unconditionally. >> >>> >>>> And inside majority of Intel PMDs we don't keep these 2 variables in sync: >>>> - mtu_set() will update both variables. >>>> - dev_configure() will update only max_rx_pkt_len, but will keep mtu intact. >>>> >>>> This patch fixes this inconsistency, which I think is a good thing. >>>> Though yes, it introduces change in behaviour. >>>> >>>> Let say the code: >>>> rte_eth_dev_set_mtu(port, 1500); >>>> dev_conf.max_rx_pkt_len = 1000; >>>> rte_eth_dev_configure(port, 1, 1, &dev_conf); >>>> >>> >>> 'rte_eth_dev_configure()' is one of the first APIs called, it is called before >>> 'rte_eth_dev_set_mtu(). >> >> Usually yes. >> But you can still do sometimes later: dev_mtu_set(); ...; dev_stop(); dev_configure(); dev_start(); >> >>> >>> When 'rte_eth_dev_configure()' is called, MTU is set to '1500' by default by >>> ethdev layer, so it is not user configuration, but 'max_rx_pkt_len' is. >> >> See above. >> PMD doesn't know where this MTU value came from (default ethdev value or user specified value) >> and probably it shouldn't care. >> >>> >>> And later, when 'rte_eth_dev_set_mtu()' is called, but MTU and 'max_rx_pkt_len' >>> are updated (mostly). >> >> Yes, in mtu_set() we update both. >> But we don't update MTU in dev_configure(), only max_rx_pkt_len. >> That what this patch tries to fix (as I understand it). > > To be more precise - it doesn't change MTU value in dev_configure(), > but instead doesn't allow max_rx_pkt_len to become smaller > then MTU + OVERHEAD. > Probably changing MTU value instead is a better choice. > +1 to change mtu for this case. And this is what happens in practice when there is no 'rte_eth_dev_set_mtu()' call, since PMD is using ('max_rx_pkt_len' - OVERHEAD) to set MTU. But this won't solve the problem Steve is trying to solve. >>> >>> >>>> Before the patch will result: >>>> mtu==1500, max_rx_pkt_len=1000; //out of sync looks wrong to me >>>> >>>> After the patch: >>>> mtu=1500, max_rx_ptk_len=1518; // in sync, change in behaviour. >>>> >>>> If you think we need to preserve current behaviour, >>>> then I suppose the easiest thing would be to change dev_config() code >>>> to update mtu value based on max_rx_pkt_len. >>>> I.E: dev_configure {...; mtu_set(max_rx_pkt_len - OVERHEAD); ...} >>>> So the code snippet above will result: >>>> mtu=982,max_rx_pkt_len=1000; >>>> >>> >>> The 'max_rx_ptk_len' is annoyance for a long time, what do you think to just >>> drop it? >>> >>> By default device will be up with default MTU (1500), later >>> 'rte_eth_dev_set_mtu' can be used to set the MTU, no frame size setting at all. >>> >>> Will this work? >> >> I think it might, but that's a big change, probably too risky at that stage... >> Defintely, I was thinking for 21.11. Let me send a deprecation notice and see what happens. >> >>> >>> >>> And for short term, for above Intel PMDs, there must be a place this >>> 'max_rx_pkt_len' value taken into account (mostly 'start()' dev_ops), that >>> function can be updated to take 'max_rx_pkt_len' only if JUMBO_FRAME set, >>> otherwise use the 'MTU' value. >> >> Even if we'll use max_rx_pkt_len only when if JUMBO_FRAME is set, >> I think we still need to keep max_rx_pkt_len and MTU values in sync. >> >>> >>> Without 'start()' updated the current logic won't work after stop & start anyway. >>> >>> >>>> >>>> >>>> >>>>> >>>>>> >>>>>> And why this same thing can't happen to other PMDs? If this is a problem for >>>>>> all PMDs, we should solve in other level, not for only some PMDs. >>>>>> >>>>> No, all PMDs exist the same issue, another proposal: >>>>> - rte_ethdev provides the unique resize 'max_rx_pkt_len' in rte_eth_dev_configure(); >>>>> - provide the uniform API for fetching the NIC's supported Ether Overhead size; >>>>> Is it feasible? >>>>> >>>>>>> >>>>>>>> Generally, the mtu value can be adjustable from user (e.g.: ip link >>>>>>>> set ens801f0 mtu 1400), hence, we just adjust the max_rx_pkt_len to >>>>>>>> satisfy mtu requirement. >>>>>>>> >>>>>>>>> Should we just call ice_mtu_set(dev, dev_conf.rxmode.max_rx_pkt_len) >>>>>>>>> here? >>>>>>>> ice_mtu_set(dev, mtu) will append ether overhead to >>>>>>>> frame_size/max_rx_pkt_len, so we need pass the mtu value as the 2nd >>>>>>>> parameter, or not the max_rx_pkt_len. >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>>> >>>>>>>>>>> And please remove above comment, since ether overhead is already >>>>>>>>>> considered in ice_mtu_set. >>>>>>>> Ether overhead is already considered in ice_mtu_set, but it also >>>>>>>> should be considered as the adjustment condition that if ice_mtu_set >>>>>> need be invoked. >>>>>>>> So, it perhaps should remain this comment before this if() condition. >>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> +ret = ice_mtu_set(dev, dev->data->mtu); if (ret != 0) return >>>>>>>>>>>> +ret; } >>>>>>>>>>>> + >>>>>>>>>>>> ret = ice_init_rss(pf); >>>>>>>>>>>> if (ret) { >>>>>>>>>>>> PMD_DRV_LOG(ERR, "Failed to enable rss for PF"); >>>>>>>>>>>> -- >>>>>>>>>>>> 2.17.1 >>>>>>>>>>> >>>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>> >>>> >