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From: Ferruh Yigit <ferruh.yigit@intel.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	Jerin Jacob <jerinj@marvell.com>,
	"Li, Xiaoyun" <xiaoyun.li@intel.com>,
	Chas Williams <chas3@att.com>,
	"Min Hu (Connor)" <humin29@huawei.com>,
	Hemant Agrawal <hemant.agrawal@nxp.com>,
	Sachin Saxena <sachin.saxena@oss.nxp.com>,
	"Zhang, Qi Z" <qi.z.zhang@intel.com>,
	"Wang, Xiao W" <xiao.w.wang@intel.com>,
	"Matan Azrad" <matan@nvidia.com>,
	Viacheslav Ovsiienko <viacheslavo@nvidia.com>,
	Harman Kalra <hkalra@marvell.com>,
	Maciej Czekaj <mczekaj@marvell.com>,
	"Ray Kinsella" <mdr@ashroe.eu>,
	"Iremonger, Bernard" <bernard.iremonger@intel.com>,
	Kiran Kumar K <kirankumark@marvell.com>,
	Nithin Dabilpuram <ndabilpuram@marvell.com>,
	"Hunt, David" <david.hunt@intel.com>,
	"Mcnamara, John" <john.mcnamara@intel.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	Igor Russkikh <irusskikh@marvell.com>,
	Steven Webster <steven.webster@windriver.com>,
	"Peters, Matt" <matt.peters@windriver.com>,
	Somalapuram Amaranath <asomalap@amd.com>,
	Rasesh Mody <rmody@marvell.com>,
	Shahed Shaikh <shshaikh@marvell.com>,
	Ajit Khaparde <ajit.khaparde@broadcom.com>,
	"Somnath Kotur" <somnath.kotur@broadcom.com>,
	Sunil Kumar Kori <skori@marvell.com>,
	Satha Rao <skoteshwar@marvell.com>,
	Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>,
	"Wang, Haiyue" <haiyue.wang@intel.com>,
	Marcin Wojtas <mw@semihalf.com>,
	Michal Krawczyk <mk@semihalf.com>,
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	Gagandeep Singh <g.singh@nxp.com>,
	"Daley, John" <johndale@cisco.com>,
	Hyong Youb Kim <hyonkim@cisco.com>,
	Ziyang Xuan <xuanziyang2@huawei.com>,
	Xiaoyun Wang <cloud.wangxiaoyun@huawei.com>,
	Guoyang Zhou <zhouguoyang@huawei.com>,
	Yisen Zhuang <yisen.zhuang@huawei.com>,
	Lijun Ou <oulijun@huawei.com>,
	"Xing, Beilei" <beilei.xing@intel.com>,
	"Wu, Jingjing" <jingjing.wu@intel.com>,
	"Yang, Qiming" <qiming.yang@intel.com>,
	Andrew Boyer <aboyer@pensando.io>,
	"Xu, Rosen" <rosen.xu@intel.com>,
	Shijith Thotton <sthotton@marvell.com>,
	Srisivasubramanian Srinivasan <srinivasan@marvell.com>,
	Zyta Szpak <zr@semihalf.com>, Liron Himi <lironh@marvell.com>,
	Heinrich Kuhn <heinrich.kuhn@corigine.com>,
	Devendra Singh Rawat <dsinghrawat@marvell.com>,
	 Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
	"Wiles, Keith" <keith.wiles@intel.com>,
	Jiawen Wu <jiawenwu@trustnetic.com>,
	Jian Wang <jianwang@trustnetic.com>,
	Maxime Coquelin <maxime.coquelin@redhat.com>,
	"Xia, Chenbo" <chenbo.xia@intel.com>,
	"Chautru, Nicolas" <nicolas.chautru@intel.com>,
	"Van Haaren, Harry" <harry.van.haaren@intel.com>,
	"Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>,
	"Nicolau, Radu" <radu.nicolau@intel.com>,
	Akhil Goyal <gakhil@marvell.com>,
	"Kantecki, Tomasz" <tomasz.kantecki@intel.com>,
	"Doherty, Declan" <declan.doherty@intel.com>,
	Pavan Nikhilesh <pbhagavatula@marvell.com>,
	"Rybalchenko, Kirill" <kirill.rybalchenko@intel.com>,
	"Singh, Jasvinder" <jasvinder.singh@intel.com>,
	Thomas Monjalon <thomas@monjalon.net>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v5 1/6] ethdev: fix max Rx packet length
Date: Mon, 11 Oct 2021 20:47:01 +0100	[thread overview]
Message-ID: <2c09db13-6b0a-86c8-32c4-03d6ce5b3433@intel.com> (raw)
In-Reply-To: <DM6PR11MB4491DD3883F5291679C0C9F89AB29@DM6PR11MB4491.namprd11.prod.outlook.com>

On 10/8/2021 4:57 PM, Ananyev, Konstantin wrote:
> 
> 
>> There is a confusion on setting max Rx packet length, this patch aims to
>> clarify it.
>>
>> 'rte_eth_dev_configure()' API accepts max Rx packet size via
>> 'uint32_t max_rx_pkt_len' field of the config struct 'struct
>> rte_eth_conf'.
>>
>> Also 'rte_eth_dev_set_mtu()' API can be used to set the MTU, and result
>> stored into '(struct rte_eth_dev)->data->mtu'.
>>
>> These two APIs are related but they work in a disconnected way, they
>> store the set values in different variables which makes hard to figure
>> out which one to use, also having two different method for a related
>> functionality is confusing for the users.
>>
>> Other issues causing confusion is:
>> * maximum transmission unit (MTU) is payload of the Ethernet frame. And
>>    'max_rx_pkt_len' is the size of the Ethernet frame. Difference is
>>    Ethernet frame overhead, and this overhead may be different from
>>    device to device based on what device supports, like VLAN and QinQ.
>> * 'max_rx_pkt_len' is only valid when application requested jumbo frame,
>>    which adds additional confusion and some APIs and PMDs already
>>    discards this documented behavior.
>> * For the jumbo frame enabled case, 'max_rx_pkt_len' is an mandatory
>>    field, this adds configuration complexity for application.
>>
>> As solution, both APIs gets MTU as parameter, and both saves the result
>> in same variable '(struct rte_eth_dev)->data->mtu'. For this
>> 'max_rx_pkt_len' updated as 'mtu', and it is always valid independent
>> from jumbo frame.
>>
>> For 'rte_eth_dev_configure()', 'dev->data->dev_conf.rxmode.mtu' is user
>> request and it should be used only within configure function and result
>> should be stored to '(struct rte_eth_dev)->data->mtu'. After that point
>> both application and PMD uses MTU from this variable.
>>
>> When application doesn't provide an MTU during 'rte_eth_dev_configure()'
>> default 'RTE_ETHER_MTU' value is used.
>>
>> Additional clarification done on scattered Rx configuration, in
>> relation to MTU and Rx buffer size.
>> MTU is used to configure the device for physical Rx/Tx size limitation,
>> Rx buffer is where to store Rx packets, many PMDs use mbuf data buffer
>> size as Rx buffer size.
>> PMDs compare MTU against Rx buffer size to decide enabling scattered Rx
>> or not. If scattered Rx is not supported by device, MTU bigger than Rx
>> buffer size should fail.
> 
> LGTM in general, one question below.
> 
> ...
> 
>> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
>> index daf5ca924221..4d0584af52e3 100644
>> --- a/lib/ethdev/rte_ethdev.c
>> +++ b/lib/ethdev/rte_ethdev.c
>> @@ -1324,6 +1324,19 @@ eth_dev_validate_offloads(uint16_t port_id, uint64_t req_offloads,
>>   	return ret;
>>   }
>>
>> +static uint16_t
>> +eth_dev_get_overhead_len(uint32_t max_rx_pktlen, uint16_t max_mtu)
>> +{
>> +	uint16_t overhead_len;
>> +
>> +	if (max_mtu != UINT16_MAX && max_rx_pktlen > max_mtu)
>> +		overhead_len = max_rx_pktlen - max_mtu;
> 
> In theory it could be overflow here, though I do realize that in practise it is unlikely situation.
> Anyway why uint16_t, why not uint32_t for all variables here?
> Just no to worry about such things.
> 

That is related to the practically expected values, it should work
fine to use 'uint32_t', so I will switch to it in next version.

  reply	other threads:[~2021-10-11 19:47 UTC|newest]

Thread overview: 112+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-09 17:29 [dpdk-dev] [PATCH 1/4] " Ferruh Yigit
2021-07-09 17:29 ` [dpdk-dev] [PATCH 2/4] ethdev: move jumbo frame offload check to library Ferruh Yigit
2021-07-13 13:48   ` Andrew Rybchenko
2021-07-21 12:26     ` Ferruh Yigit
2021-07-18  7:49   ` Xu, Rosen
2021-07-19 14:38   ` Ajit Khaparde
2021-07-09 17:29 ` [dpdk-dev] [PATCH 3/4] ethdev: move check to library for MTU set Ferruh Yigit
2021-07-13 13:56   ` Andrew Rybchenko
2021-07-18  7:52   ` Xu, Rosen
2021-07-09 17:29 ` [dpdk-dev] [PATCH 4/4] ethdev: remove jumbo offload flag Ferruh Yigit
2021-07-13 14:07   ` Andrew Rybchenko
2021-07-21 12:26     ` Ferruh Yigit
2021-07-21 12:39     ` Ferruh Yigit
2021-07-18  7:53   ` Xu, Rosen
2021-07-13 12:47 ` [dpdk-dev] [PATCH 1/4] ethdev: fix max Rx packet length Andrew Rybchenko
2021-07-21 16:46   ` Ferruh Yigit
2021-07-22  1:31     ` Ajit Khaparde
2021-07-22 10:27       ` Ferruh Yigit
2021-07-22 10:38         ` Andrew Rybchenko
2021-07-18  7:45 ` Xu, Rosen
2021-07-19  3:35 ` Huisong Li
2021-07-21 15:29   ` Ferruh Yigit
2021-07-22  7:21     ` Huisong Li
2021-07-22 10:12       ` Ferruh Yigit
2021-07-22 10:15         ` Andrew Rybchenko
2021-07-22 14:43           ` Stephen Hemminger
2021-09-17  1:08             ` Min Hu (Connor)
2021-09-17  8:04               ` Ferruh Yigit
2021-09-17  8:16                 ` Min Hu (Connor)
2021-09-17  8:17                 ` Min Hu (Connor)
2021-07-22 17:21 ` [dpdk-dev] [PATCH v2 1/6] " Ferruh Yigit
2021-07-22 17:21   ` [dpdk-dev] [PATCH v2 2/6] ethdev: move jumbo frame offload check to library Ferruh Yigit
2021-07-22 17:21   ` [dpdk-dev] [PATCH v2 3/6] ethdev: move check to library for MTU set Ferruh Yigit
2021-07-22 17:21   ` [dpdk-dev] [PATCH v2 4/6] ethdev: remove jumbo offload flag Ferruh Yigit
2021-07-22 17:21   ` [dpdk-dev] [PATCH v2 5/6] ethdev: unify MTU checks Ferruh Yigit
2021-07-23  3:29     ` Huisong Li
2021-07-22 17:21   ` [dpdk-dev] [PATCH v2 6/6] examples/ip_reassembly: remove unused parameter Ferruh Yigit
2021-10-01 14:36   ` [dpdk-dev] [PATCH v3 1/6] ethdev: fix max Rx packet length Ferruh Yigit
2021-10-01 14:36     ` [dpdk-dev] [PATCH v3 2/6] ethdev: move jumbo frame offload check to library Ferruh Yigit
2021-10-04  5:08       ` Somnath Kotur
2021-10-01 14:36     ` [dpdk-dev] [PATCH v3 3/6] ethdev: move check to library for MTU set Ferruh Yigit
2021-10-04  5:09       ` Somnath Kotur
2021-10-01 14:36     ` [dpdk-dev] [PATCH v3 4/6] ethdev: remove jumbo offload flag Ferruh Yigit
     [not found]       ` <CAOBf=muYkU2dwgi3iC8Q7pdSNTJsMUwWYdXj14KeN_=_mUGa0w@mail.gmail.com>
2021-10-04  7:55         ` Somnath Kotur
2021-10-05 16:48           ` Ferruh Yigit
2021-10-01 14:36     ` [dpdk-dev] [PATCH v3 5/6] ethdev: unify MTU checks Ferruh Yigit
2021-10-01 14:36     ` [dpdk-dev] [PATCH v3 6/6] examples/ip_reassembly: remove unused parameter Ferruh Yigit
2021-10-01 15:07     ` [dpdk-dev] [PATCH v3 1/6] ethdev: fix max Rx packet length Stephen Hemminger
2021-10-05 16:46       ` Ferruh Yigit
2021-10-05 17:16     ` [dpdk-dev] [PATCH v4 " Ferruh Yigit
2021-10-05 17:16       ` [dpdk-dev] [PATCH v4 2/6] ethdev: move jumbo frame offload check to library Ferruh Yigit
2021-10-08  8:39         ` Xu, Rosen
2021-10-05 17:16       ` [dpdk-dev] [PATCH v4 3/6] ethdev: move check to library for MTU set Ferruh Yigit
2021-10-05 17:16       ` [dpdk-dev] [PATCH v4 4/6] ethdev: remove jumbo offload flag Ferruh Yigit
2021-10-08  8:38         ` Xu, Rosen
2021-10-05 17:16       ` [dpdk-dev] [PATCH v4 5/6] ethdev: unify MTU checks Ferruh Yigit
2021-10-05 17:16       ` [dpdk-dev] [PATCH v4 6/6] examples/ip_reassembly: remove unused parameter Ferruh Yigit
2021-10-05 22:07       ` [dpdk-dev] [PATCH v4 1/6] ethdev: fix max Rx packet length Ajit Khaparde
2021-10-06  6:08         ` Somnath Kotur
2021-10-08  8:36       ` Xu, Rosen
2021-10-10  6:30       ` Matan Azrad
2021-10-11 21:59         ` Ferruh Yigit
2021-10-12  7:03           ` Matan Azrad
2021-10-12 11:03             ` Ferruh Yigit
2021-10-07 16:56     ` [dpdk-dev] [PATCH v5 " Ferruh Yigit
2021-10-07 16:56       ` [dpdk-dev] [PATCH v5 2/6] ethdev: move jumbo frame offload check to library Ferruh Yigit
2021-10-08 17:20         ` Ananyev, Konstantin
2021-10-09 10:58         ` lihuisong (C)
2021-10-07 16:56       ` [dpdk-dev] [PATCH v5 3/6] ethdev: move check to library for MTU set Ferruh Yigit
2021-10-08 17:19         ` Ananyev, Konstantin
2021-10-07 16:56       ` [dpdk-dev] [PATCH v5 4/6] ethdev: remove jumbo offload flag Ferruh Yigit
2021-10-08 17:11         ` Ananyev, Konstantin
2021-10-09 11:09           ` lihuisong (C)
2021-10-10  5:46         ` Matan Azrad
2021-10-07 16:56       ` [dpdk-dev] [PATCH v5 5/6] ethdev: unify MTU checks Ferruh Yigit
2021-10-08 16:51         ` Ananyev, Konstantin
2021-10-11 19:50           ` Ferruh Yigit
2021-10-09 11:43         ` lihuisong (C)
2021-10-11 20:15           ` Ferruh Yigit
2021-10-12  4:02             ` lihuisong (C)
2021-10-07 16:56       ` [dpdk-dev] [PATCH v5 6/6] examples/ip_reassembly: remove unused parameter Ferruh Yigit
2021-10-08 16:53         ` Ananyev, Konstantin
2021-10-08 15:57       ` [dpdk-dev] [PATCH v5 1/6] ethdev: fix max Rx packet length Ananyev, Konstantin
2021-10-11 19:47         ` Ferruh Yigit [this message]
2021-10-09 10:56       ` lihuisong (C)
2021-10-11 23:53     ` [dpdk-dev] [PATCH v6 " Ferruh Yigit
2021-10-11 23:53       ` [dpdk-dev] [PATCH v6 2/6] ethdev: move jumbo frame offload check to library Ferruh Yigit
2021-10-11 23:53       ` [dpdk-dev] [PATCH v6 3/6] ethdev: move check to library for MTU set Ferruh Yigit
2021-10-11 23:53       ` [dpdk-dev] [PATCH v6 4/6] ethdev: remove jumbo offload flag Ferruh Yigit
2021-10-12 17:20         ` Hyong Youb Kim (hyonkim)
2021-10-13  7:16         ` Michał Krawczyk
2021-10-11 23:53       ` [dpdk-dev] [PATCH v6 5/6] ethdev: unify MTU checks Ferruh Yigit
2021-10-12  5:58         ` Andrew Rybchenko
2021-10-11 23:53       ` [dpdk-dev] [PATCH v6 6/6] examples/ip_reassembly: remove unused parameter Ferruh Yigit
2021-10-12  6:02       ` [dpdk-dev] [PATCH v6 1/6] ethdev: fix max Rx packet length Andrew Rybchenko
2021-10-12  9:42       ` Ananyev, Konstantin
2021-10-13  7:08       ` Xu, Rosen
2021-10-15  1:31       ` Hyong Youb Kim (hyonkim)
2021-10-16  0:24       ` Ferruh Yigit
2021-10-18  8:54         ` Ferruh Yigit
2021-10-18 13:48     ` [dpdk-dev] [PATCH v7 " Ferruh Yigit
2021-10-18 13:48       ` [dpdk-dev] [PATCH v7 2/6] ethdev: move jumbo frame offload check to library Ferruh Yigit
2021-10-18 13:48       ` [dpdk-dev] [PATCH v7 3/6] ethdev: move check to library for MTU set Ferruh Yigit
2021-10-18 13:48       ` [dpdk-dev] [PATCH v7 4/6] ethdev: remove jumbo offload flag Ferruh Yigit
2021-10-21  0:43         ` Thomas Monjalon
2021-10-22 11:25           ` Ferruh Yigit
2021-10-22 11:29             ` Andrew Rybchenko
2021-10-18 13:48       ` [dpdk-dev] [PATCH v7 5/6] ethdev: unify MTU checks Ferruh Yigit
2021-10-18 13:48       ` [dpdk-dev] [PATCH v7 6/6] examples/ip_reassembly: remove unused parameter Ferruh Yigit
2021-10-18 17:31       ` [dpdk-dev] [PATCH v7 1/6] ethdev: fix max Rx packet length Ferruh Yigit
2021-11-05 14:19         ` Xueming(Steven) Li
2021-11-05 14:39           ` Ferruh Yigit

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