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From: Ferruh Yigit <ferruh.yigit@intel.com>
To: oulijun <oulijun@huawei.com>, Steve Yang <stevex.yang@intel.com>,
	dev@dpdk.org
Cc: thomas@monjalon.net, andrew.rybchenko@oktetlabs.ru,
	linuxarm@openeuler.org
Subject: Re: [dpdk-dev] [PATCH v3 01/22] ethdev: fix MTU size exceeds max rx packet length
Date: Mon, 18 Jan 2021 10:42:03 +0000	[thread overview]
Message-ID: <7ec898cd-60b0-0d8d-b006-06d6ac3822b8@intel.com> (raw)
In-Reply-To: <c79413fe-06ab-a2eb-96ec-d55d968fd2b2@huawei.com>

On 1/15/2021 10:44 AM, oulijun wrote:
> Hi Steve
> This is a very good job! But I have some question and suggestions.
> Please check it.
> 
> 在 2021/1/14 17:45, Steve Yang 写道:
>> Ethdev is using default Ethernet overhead to decide if provided
>> 'max_rx_pkt_len' value is bigger than max (non jumbo) MTU value,
>> and limits it to MAX if it is.
>>
>> Since the application/driver used Ethernet overhead is different than
>> the ethdev one, check result is wrong.
>>
>> If the driver is using Ethernet overhead bigger than the default one,
>> the provided 'max_rx_pkt_len' is trimmed down, and in the driver when
>> correct Ethernet overhead is used to convert back, the resulting MTU is
>> less than the intended one, causing some packets to be dropped.
>>
>> Like,
>> app     -> max_rx_pkt_len = 1500/*mtu*/ + 22/*overhead*/ = 1522
>> ethdev  -> 1522 > 1518/*MAX*/; max_rx_pkt_len = 1518
>> driver  -> MTU = 1518 - 22 = 1496
>> Packets with size 1497-1500 are dropped although intention is to be able
>> to send/receive them.
>>
>> The fix is to make ethdev use the correct Ethernet overhead for port,
>> instead of default one.
>>
>> Fixes: 59d0ecdbf0e1 ("ethdev: MTU accessors")
>>
>> Signed-off-by: Steve Yang <stevex.yang@intel.com>
>> ---
>>   lib/librte_ethdev/rte_ethdev.c | 27 ++++++++++++++++++++++++---
>>   1 file changed, 24 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
>> index 17ddacc78d..19ca4c4512 100644
>> --- a/lib/librte_ethdev/rte_ethdev.c
>> +++ b/lib/librte_ethdev/rte_ethdev.c
>> @@ -1292,8 +1292,10 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t 
>> nb_rx_q, uint16_t nb_tx_q,
>>       struct rte_eth_dev *dev;
>>       struct rte_eth_dev_info dev_info;
>>       struct rte_eth_conf orig_conf;
>> +    uint16_t overhead_len;
>>       int diag;
>>       int ret;
>> +    uint16_t old_mtu;
>>       RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>> @@ -1319,10 +1321,20 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t 
>> nb_rx_q, uint16_t nb_tx_q,
>>           memcpy(&dev->data->dev_conf, dev_conf,
>>                  sizeof(dev->data->dev_conf));
>> +    /* Backup mtu for rollback */
>> +    old_mtu = dev->data->mtu;
>> +
>>       ret = rte_eth_dev_info_get(port_id, &dev_info);
>>       if (ret != 0)
>>           goto rollback;
>> +    /* Get the real Ethernet overhead length */
>> +    if (dev_info.max_mtu != UINT16_MAX &&
>> +        dev_info.max_rx_pktlen > dev_info.max_mtu)
>> +        overhead_len = dev_info.max_rx_pktlen - dev_info.max_mtu;
>> +    else
>> +        overhead_len = RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
>> +
> The Ethernet frame header length supported by each NIC may be different, which 
> cause the difference of allowed packets size and drop you say.
> The diference of Ethernet frame header length have an impact for the maximum 
> Ethernet frame length, which is a boundary value
> of enabling jumbo frame through the ' max_rx_pkt_len '.
> However, we need to do the same thing you do above to get the overhead_len every 
> time, which will
> cause a lot of duplicate code in the framework and app. For examples, parsing 
> and processing for '--max-pkt-len=xxx' parameter,
>   and " cmd_config_max_pkt_len_parsed " in testpmd, and here modifying here 
> dev_configure API.
> It's a little redundant and troublesome.
> 
> Maybe, it is necessary for driver to directly report the supported maximum 
> Ethernet frame length by rte_dev_info_get API.
> As following:
> struct rte_eth_dev_info {
>      xxxx
>      /**
>       * The maximum Ethernet frame length supported by each
>       * driver varies with the Ethernet header length.
>       */
>      uint16_t eth_max_len;
>      xxxx
> }
> 
> int
> rte_eth_dev_info_get(uint16_t port_id, struct rte_eth_dev_info *dev_info)
> {
>      xxx
>      dev_info->min_mtu = RTE_ETHER_MIN_MTU;
>      dev_info->max_mtu = UINT16_MAX;
>      dev_info->eth_max_len = RTE_ETHER_MAX_LEN;
>      xxx
> }
> 
> And then:
> xxx_devv_infos_get(struct rte_eth_dev *eth_dev, struct rte_eth_dev_info *info)
> {
>      xxx
>      info->eth_max_len = xxx_ETHER_MAX _LEN;
>      xxx
> }
> What do you think?

Hi Lijun,

The 'max_mtu' has been added in the past to solve exact same problem, perhaps it 
would be better to add something like 'eth_max_len' at that time.

But as Steve mentioned we are planning to switch to more MTU based 
configuration, which should remove the need of the field you mentioned.

>>       /* If number of queues specified by application for both Rx and Tx is
>>        * zero, use driver preferred values. This cannot be done individually
>>        * as it is valid for either Tx or Rx (but not both) to be zero.
>> @@ -1410,11 +1422,18 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t 
>> nb_rx_q, uint16_t nb_tx_q,
>>               goto rollback;
>>           }
>>       } else {
>> -        if (dev_conf->rxmode.max_rx_pkt_len < RTE_ETHER_MIN_LEN ||
>> -            dev_conf->rxmode.max_rx_pkt_len > RTE_ETHER_MAX_LEN)
>> +        uint16_t pktlen = dev_conf->rxmode.max_rx_pkt_len;
>> +        if (pktlen < RTE_ETHER_MIN_MTU + overhead_len ||
>> +            pktlen > RTE_ETHER_MTU + overhead_len)
>>               /* Use default value */
>>               dev->data->dev_conf.rxmode.max_rx_pkt_len =
>> -                            RTE_ETHER_MAX_LEN;
>> +                        RTE_ETHER_MTU + overhead_len;
>> +    }
>> +
>> +    /* Scale the MTU size to adapt max_rx_pkt_len */
>> +    if (dev_conf->rxmode.offloads & DEV_RX_OFFLOAD_JUMBO_FRAME) {
>> +        dev->data->mtu = dev->data->dev_conf.rxmode.max_rx_pkt_len -
>> +                overhead_len;
>>       }
> Now that we update mtu here when jumbo frame enabled. It is necessary to check 
> validity of max_rx_pkt_len.
> As following:
> if (dev_conf->rxmode.offloads & DEV_RX_OFFLOAD_JUMBO_FRAME) {
>      if (dev_conf->rxmode.max_rx_pkt_len > dev_info.max_rx_pktlen ||
>          dev_conf->rxmode.max_rx_pkt_len <=  RTE_ETHER_MTU + overhead_len) {

It is not clear from API that if "max_rx_pkt_len <=  RTE_ETHER_MTU + 
overhead_len" is a valid value or not, the API says:
"max_rx_pkt_len;  /**< Only used if JUMBO_FRAME enabled. */"

But it doesn't say that when 'DEV_RX_OFFLOAD_JUMBO_FRAME' is set, 
'max_rx_pkt_len' should be less then 'RTE_ETHER_MTU'

>              xxxx
>          }
> } else {
>          xxx
> }
> 
> If it does not thing above, which will cause an unreasonable case.
> Like,
> dev_conf->rxmode.offloads & DEV_RX_OFFLOAD_JUMBO_FRAME == 1
> dev_conf->rxmode.max_rx_pkt_len = 1500
> overhead_len = 26
> dev->data->mtu = dev_conf->rxmode.max_rx_pkt_len - overhead_len = 1500 - 26 = 1474
> 

This looks correct, if the applicatin is requesting 'max_rx_pkt_len = 1500', the 
requeted MTU is 1474,
if application wants an MTU as 1500, it should set the 'max_rx_pkt_len' as "1500 
+ overhead".

> In fact, DEV_RX_OFFLOAD_JUMBO_FRAME is set to rxmode.offloads when mtu > 1500.

Overall the 'max_rx_pkt_len' setting is a little messy, it has been tried to fix 
in last release but we reverted them because of unexpected side affects.

Current long term plan is,
- Switch both 'rte_eth_dev_configure()' & 'rte_eth_dev_set_mtu()' to work on MTU 
values. (instead one working on frame lenght and other on MTU)
- Remove the 'DEV_RX_OFFLOAD_JUMBO_FRAME' and decide jumbo frame request by 
requested MTU value check
- App decide the jumbo frame capability from the 'max_mtu' check
- App calculate Ethernet overhead using 'max_mtu' and 'max_rx_pktlen'

>>       /*
>> @@ -1549,6 +1568,8 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t 
>> nb_rx_q, uint16_t nb_tx_q,
>>       eth_dev_tx_queue_config(dev, 0);
>>   rollback:
>>       memcpy(&dev->data->dev_conf, &orig_conf, sizeof(dev->data->dev_conf));
>> +    if (old_mtu != dev->data->mtu)
>> +        dev->data->mtu = old_mtu;
>>       rte_ethdev_trace_configure(port_id, nb_rx_q, nb_tx_q, dev_conf, ret);
>>       return ret;
>>


  reply	other threads:[~2021-01-18 10:42 UTC|newest]

Thread overview: 115+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-09  3:16 [dpdk-dev] [PATCH v1 00/12] fix rx packets dropped issue Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 01/12] net/dpaa2: fix the jumbo frame flag condition for mtu set Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 02/12] net/e1000: " Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 03/12] net/hns3: " Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 04/12] net/i40e: fix the jumbo frame flag condition Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 05/12] net/iavf: " Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 06/12] net/ice: " Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 07/12] net/ipn3ke: fix the jumbo frame flag condition for mtu set Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 08/12] net/octeontx: " Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 09/12] net/octeontx2: fix the jumbo frame flag condition for mtu Steve Yang
2020-12-21  7:16   ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 10/12] net/qede: fix the jumbo frame flag condition for mtu set Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 11/12] net/sfc: " Steve Yang
2020-12-09  3:16 ` [dpdk-dev] [PATCH v1 12/12] net/thunderx: " Steve Yang
2020-12-11  4:31 ` [dpdk-dev] [PATCH v1 00/12] fix rx packets dropped issue Guo, Jia
2020-12-14 17:44 ` Ferruh Yigit
2020-12-17  9:22 ` [dpdk-dev] [PATCH v2 00/22] " Steve Yang
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 01/22] ethdev: fix MTU size exceeds max rx packet length Steve Yang
2020-12-28 14:51     ` Andrew Rybchenko
2021-01-13 10:32       ` Ferruh Yigit
2020-12-30 10:19     ` oulijun
     [not found]       ` <DM6PR11MB43627F10DDAFC9801816FF5BF9D00@DM6PR11MB4362.namprd11.prod.outlook.com>
2021-01-13 10:25         ` Ferruh Yigit
2021-01-13 11:04         ` Ferruh Yigit
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 02/22] app/testpmd: fix max rx packet length for VLAN packets Steve Yang
2021-01-13 11:26     ` Ferruh Yigit
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 03/22] net/dpaa: fix the jumbo frame flag condition for mtu set Steve Yang
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 04/22] net/dpaa2: " Steve Yang
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 05/22] net/e1000: " Steve Yang
2020-12-18  2:42     ` Guo, Jia
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 06/22] net/hns3: " Steve Yang
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 07/22] net/i40e: fix the jumbo frame flag condition Steve Yang
2020-12-18  2:44     ` Guo, Jia
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 08/22] net/iavf: " Steve Yang
2020-12-17  9:22   ` [dpdk-dev] [PATCH v2 09/22] net/ice: " Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 10/22] net/ipn3ke: fix the jumbo frame flag condition for mtu set Steve Yang
2020-12-19  0:54     ` Xu, Rosen
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 11/22] net/octeontx: " Steve Yang
2020-12-21 15:04     ` [dpdk-dev] [EXT] " Harman Kalra
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 12/22] net/octeontx2: fix the jumbo frame flag condition for mtu Steve Yang
2020-12-18 10:15     ` Nithin Dabilpuram
2020-12-21  7:19     ` [dpdk-dev] [EXT] " Sunil Kumar Kori
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 13/22] net/qede: fix the jumbo frame flag condition for mtu set Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 14/22] net/sfc: " Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 15/22] net/thunderx: " Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 16/22] net/ixgbe: fix the jumbo frame flag condition Steve Yang
2020-12-18  2:43     ` Guo, Jia
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 17/22] net/cxgbe: " Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 18/22] net/axgbe: fix the jumbo frame flag condition for mtu set Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 19/22] net/enetc: " Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 20/22] net/hinic: " Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 21/22] net/nfp: " Steve Yang
2020-12-17  9:23   ` [dpdk-dev] [PATCH v2 22/22] net/liquidio: " Steve Yang
2021-01-13 11:32   ` [dpdk-dev] [PATCH v2 00/22] fix rx packets dropped issue Ferruh Yigit
2021-01-14  9:45   ` [dpdk-dev] [PATCH v3 " Steve Yang
2021-01-14  9:45   ` [dpdk-dev] [PATCH v3 01/22] ethdev: fix MTU size exceeds max rx packet length Steve Yang
2021-01-14 16:36     ` Ferruh Yigit
2021-01-14 17:13       ` Ferruh Yigit
2021-01-14 17:29         ` Andrew Boyer
2021-01-14 20:44           ` Ferruh Yigit
2021-01-15 10:44     ` oulijun
2021-01-18 10:42       ` Ferruh Yigit [this message]
2021-01-19  8:46         ` oulijun
2021-01-23  9:05           ` oulijun
2021-01-25 12:22           ` Ferruh Yigit
2021-01-18  7:04     ` [dpdk-dev] [PATCH v4 00/22] fix rx packets dropped issue Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 01/22] ethdev: fix MTU size exceeds max rx packet length Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 02/22] app/testpmd: fix max rx packet length for VLAN packets Steve Yang
2021-01-21 15:27         ` Lance Richardson
2021-01-22 14:26           ` Lance Richardson
2021-01-25 12:14           ` Ferruh Yigit
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 03/22] net/dpaa: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 04/22] net/dpaa2: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 05/22] net/e1000: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 06/22] net/hns3: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 07/22] net/i40e: fix the jumbo frame flag condition Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 08/22] net/iavf: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 09/22] net/ice: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 10/22] net/ipn3ke: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 11/22] net/octeontx: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 12/22] net/octeontx2: fix the jumbo frame flag condition for mtu Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 13/22] net/qede: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 14/22] net/sfc: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 15/22] net/thunderx: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 16/22] net/ixgbe: fix the jumbo frame flag condition Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 17/22] net/cxgbe: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 18/22] net/axgbe: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 19/22] net/enetc: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 20/22] net/hinic: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 21/22] net/nfp: " Steve Yang
2021-01-18  7:04       ` [dpdk-dev] [PATCH v4 22/22] net/liquidio: " Steve Yang
2021-01-18 11:54       ` [dpdk-dev] [PATCH v4 00/22] fix rx packets dropped issue Ferruh Yigit
2021-01-14  9:45   ` [dpdk-dev] [PATCH v3 02/22] app/testpmd: fix max rx packet length for VLAN packets Steve Yang
2021-01-14  9:45   ` [dpdk-dev] [PATCH v3 03/22] net/dpaa: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-14 10:26     ` Hemant Agrawal
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 04/22] net/dpaa2: " Steve Yang
2021-01-14 10:27     ` Hemant Agrawal
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 05/22] net/e1000: " Steve Yang
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 06/22] net/hns3: " Steve Yang
2021-01-18  1:30     ` oulijun
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 07/22] net/i40e: fix the jumbo frame flag condition Steve Yang
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 08/22] net/iavf: " Steve Yang
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 09/22] net/ice: " Steve Yang
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 10/22] net/ipn3ke: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 11/22] net/octeontx: " Steve Yang
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 12/22] net/octeontx2: fix the jumbo frame flag condition for mtu Steve Yang
2021-01-14  9:46   ` [dpdk-dev] [PATCH v3 13/22] net/qede: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 14/22] net/sfc: " Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 15/22] net/thunderx: " Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 16/22] net/ixgbe: fix the jumbo frame flag condition Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 17/22] net/cxgbe: " Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 18/22] net/axgbe: fix the jumbo frame flag condition for mtu set Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 19/22] net/enetc: " Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 20/22] net/hinic: " Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 21/22] net/nfp: " Steve Yang
2021-01-14  9:47   ` [dpdk-dev] [PATCH v3 22/22] net/liquidio: " Steve Yang

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