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From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Matan Azrad <matan@mellanox.com>,
	Dekel Peled <dekelp@mellanox.com>,
	"john.mcnamara@intel.com" <john.mcnamara@intel.com>,
	"marko.kovacevic@intel.com" <marko.kovacevic@intel.com>,
	"nhorman@tuxdriver.com" <nhorman@tuxdriver.com>,
	"ajit.khaparde@broadcom.com" <ajit.khaparde@broadcom.com>,
	"somnath.kotur@broadcom.com" <somnath.kotur@broadcom.com>,
	"anatoly.burakov@intel.com" <anatoly.burakov@intel.com>,
	"xuanziyang2@huawei.com" <xuanziyang2@huawei.com>,
	"cloud.wangxiaoyun@huawei.com" <cloud.wangxiaoyun@huawei.com>,
	"zhouguoyang@huawei.com" <zhouguoyang@huawei.com>,
	"wenzhuo.lu@intel.com" <wenzhuo.lu@intel.com>,
	"konstantin.ananyev@intel.com" <konstantin.ananyev@intel.com>,
	Shahaf Shuler <shahafs@mellanox.com>,
	Slava Ovsiienko <viacheslavo@mellanox.com>,
	"rmody@marvell.com" <rmody@marvell.com>,
	"shshaikh@marvell.com" <shshaikh@marvell.com>,
	"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
	"tiwei.bie@intel.com" <tiwei.bie@intel.com>,
	"zhihong.wang@intel.com" <zhihong.wang@intel.com>,
	"yongwang@vmware.com" <yongwang@vmware.com>,
	Thomas Monjalon <thomas@monjalon.net>,
	"arybchenko@solarflare.com" <arybchenko@solarflare.com>,
	"jingjing.wu@intel.com" <jingjing.wu@intel.com>,
	"bernard.iremonger@intel.com" <bernard.iremonger@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v4 1/3] ethdev: support API to set max LRO packet size
Date: Fri, 8 Nov 2019 12:51:48 +0000
Message-ID: <60dc4ef1-7e9a-5073-c534-e3b7a42a9abf@intel.com> (raw)
In-Reply-To: <AM0PR0502MB40197D18E5F48633075AADBBD27B0@AM0PR0502MB4019.eurprd05.prod.outlook.com>

On 11/8/2019 11:56 AM, Matan Azrad wrote:
> 
> 
> From: Ferruh Yigit
>> On 11/8/2019 10:10 AM, Matan Azrad wrote:
>>>
>>>
>>> From: Ferruh Yigit
>>>> On 11/8/2019 6:54 AM, Matan Azrad wrote:
>>>>> Hi
>>>>>
>>>>> From: Ferruh Yigit
>>>>>> On 11/7/2019 12:35 PM, Dekel Peled wrote:
>>>>>>> @@ -1266,6 +1286,18 @@ struct rte_eth_dev *
>>>>>>>
>>>>>> 	RTE_ETHER_MAX_LEN;
>>>>>>>  	}
>>>>>>>
>>>>>>> +	/*
>>>>>>> +	 * If LRO is enabled, check that the maximum aggregated
>> packet
>>>>>>> +	 * size is supported by the configured device.
>>>>>>> +	 */
>>>>>>> +	if (dev_conf->rxmode.offloads &
>> DEV_RX_OFFLOAD_TCP_LRO) {
>>>>>>> +		ret = check_lro_pkt_size(
>>>>>>> +				port_id, dev_conf-
>>>>>>> rxmode.max_lro_pkt_size,
>>>>>>> +				dev_info.max_lro_pkt_size);
>>>>>>> +		if (ret != 0)
>>>>>>> +			goto rollback;
>>>>>>> +	}
>>>>>>> +
>>>>>>
>>>>>> This check forces applications that enable LRO to provide
>>>> 'max_lro_pkt_size'
>>>>>> config value.
>>>>>
>>>>> Yes.(we can break an API, we noticed it)
>>>>
>>>> I am not talking about API/ABI breakage, that part is OK.
>>>> With this check, if the application requested LRO offload but not
>>>> provided 'max_lro_pkt_size' value, device configuration will fail.
>>>>
>>> Yes
>>>> Can there be a case application is good with whatever the PMD can
>>>> support as max?
>>> Yes can be - you know, we can do everything we want but it is better to be
>> consistent:
>>> Due to the fact of Max rx pkt len field is mandatory for JUMBO offload, max
>> lro pkt len should be mandatory for LRO offload.
>>>
>>> So your question is actually why both, non-lro packets and LRO packets max
>> size are mandatory...
>>>
>>>
>>> I think it should be important values for net applications management.
>>> Also good for mbuf size managements.
>>>
>>>>>
>>>>>> - Why it is mandatory now, how it was working before if it is
>>>>>> mandatory value?
>>>>>
>>>>> It is the same as max_rx_pkt_len which is mandatory for jumbo frame
>>>> offload.
>>>>> So now, when the user configures a LRO offload he must to set max
>>>>> lro pkt
>>>> len.
>>>>> We don't want to confuse the user here with the max rx pkt len
>>>> configurations and behaviors, they should be with same logic.
>>>>>
>>>>> This parameter defines well the LRO behavior.
>>>>> Before this, each PMD took its own interpretation to what should be
>>>>> the
>>>> maximum size for LRO aggregated packets.
>>>>> Now, the user must say what is his intension, and the ethdev can
>>>>> limit it
>>>> according to the device capability.
>>>>> By this way, also, the PMD can organize\optimize its data-path more.
>>>>> Also, the application can create different mempools for LRO queues
>>>>> to
>>>> allow bigger packet receiving for LRO traffic.
>>>>>
>>>>>> - What happens if PMD doesn't provide 'max_lro_pkt_size', so it is '0'?
>>>>> Yes, you can see the feature description Dekel added.
>>>>> This patch also updates all the PMDs support an LRO for non-0 value.
>>>>
>>>> Of course I can see the updates Matan, my point is "What happens if
>>>> PMD doesn't provide 'max_lro_pkt_size'",
>>>> 1) There is no check for it right, so it is acceptable?
>>>
>>> There is check.
>>> If the capability is 0, any non-zero configuration will fail.
>>>
>>>> 2) Are we making this filed mandatory to provide for PMDs, it is easy
>>>> to make new fields mandatory for PMDs but is this really necessary?
>>>
>>> Yes, for consistence.
>>>
>>>>>
>>>>> as same as max rx pkt len, no?
>>>>>
>>>>>> - What do you think setting 'max_lro_pkt_size' config value to what
>>>>>> PMD provided if application doesn't provide it?
>>>>> Same answers as above.
>>>>>
>>>>
>>>> If application doesn't care the value, as it has been till now, and
>>>> not provided explicit 'max_lro_pkt_size', why not ethdev level use
>>>> the value provided by PMD instead of failing?
>>>
>>> Again, same question we can ask on max rx pkt len.
>>>
>>> Looks like the packet size is very important value which should be set by
>> the application.
>>>
>>> Previous applications have no option to configure it, so they haven't
>> configure it, (probably cover it somehow) I think it is our miss to supply this
>> info.
>>>
>>> Let's do it in same way as we do max rx pkt len (as this patch main idea).
>>> Later, we can change both to other meaning.
>>>
>>
>> I think it is not a good reason to introduce a new mandatory config option for
>> application because of 'max_rx_pkt_len' does it.
> 
> It is mandatory only if LRO offload is configured.
> 
>> Will it work, if:
>> - If application doesn't provide this value, use the PMD max
> 
> May cause a problem if the mbuf size is not enough for the PMD maximum.

OK, this is what I was missing, for this case I was thinking max_rx_pkt_len will
be used but you already explained that application may want to use different
mempools for LRO queues.

For this case shouldn't PMDs take the 'rxmode.max_lro_pkt_size' into account and
program the device accordingly (of course in LRO enabled case) ?
This part seems missing and should be highlighted to other PMD maintainers.

>  
>> - If both application and PMD doesn't provide this value, fail on configure()?
> 
> It will work.
> In my opinion - not ideal.
> 
> Matan
> 
> 


  reply index

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-05  8:40 [dpdk-dev] [PATCH 0/3] " Dekel Peled
2019-11-05  8:40 ` [dpdk-dev] [PATCH 1/3] ethdev: " Dekel Peled
2019-11-05 12:39   ` Andrew Rybchenko
2019-11-05 13:09     ` Thomas Monjalon
2019-11-05 14:18     ` Dekel Peled
2019-11-05 14:27       ` Andrew Rybchenko
2019-11-05 14:51         ` Dekel Peled
2019-11-05  8:40 ` [dpdk-dev] [PATCH 2/3] net/mlx5: use " Dekel Peled
2019-11-05  8:40 ` [dpdk-dev] [PATCH 3/3] app/testpmd: " Dekel Peled
2019-11-05  9:35 ` [dpdk-dev] [PATCH 0/3] support " Matan Azrad
2019-11-06 11:34 ` [dpdk-dev] [PATCH v2 " Dekel Peled
2019-11-06 11:34   ` [dpdk-dev] [PATCH v2 1/3] ethdev: " Dekel Peled
2019-11-06 12:26     ` Thomas Monjalon
2019-11-06 12:39       ` Dekel Peled
2019-11-06 11:34   ` [dpdk-dev] [PATCH v2 2/3] net/mlx5: use " Dekel Peled
2019-11-06 11:34   ` [dpdk-dev] [PATCH v2 3/3] app/testpmd: " Dekel Peled
2019-11-06 12:35     ` Iremonger, Bernard
2019-11-06 13:14       ` Dekel Peled
2019-11-06 14:28   ` [dpdk-dev] [PATCH v3 0/3] support " Dekel Peled
2019-11-06 14:28     ` [dpdk-dev] [PATCH v3 1/3] ethdev: " Dekel Peled
2019-11-07 11:57       ` [dpdk-dev] [EXT] " Shahed Shaikh
2019-11-07 12:18         ` Dekel Peled
2019-11-06 14:28     ` [dpdk-dev] [PATCH v3 2/3] net/mlx5: use " Dekel Peled
2019-11-06 14:28     ` [dpdk-dev] [PATCH v3 3/3] app/testpmd: " Dekel Peled
2019-11-06 16:41     ` [dpdk-dev] [PATCH v3 0/3] support " Iremonger, Bernard
2019-11-07  6:10       ` Dekel Peled
2019-11-07 12:35     ` [dpdk-dev] [PATCH v4 " Dekel Peled
2019-11-07 12:35       ` [dpdk-dev] [PATCH v4 1/3] ethdev: " Dekel Peled
2019-11-07 20:15         ` Ferruh Yigit
2019-11-08  6:54           ` Matan Azrad
2019-11-08  9:19             ` Ferruh Yigit
2019-11-08 10:10               ` Matan Azrad
2019-11-08 11:37                 ` Ferruh Yigit
2019-11-08 11:56                   ` Matan Azrad
2019-11-08 12:51                     ` Ferruh Yigit [this message]
2019-11-08 16:11                       ` Dekel Peled
2019-11-08 16:53                         ` Ferruh Yigit
2019-11-09 18:20                       ` Matan Azrad
2019-11-10 23:40                         ` Ananyev, Konstantin
2019-11-11  8:01                           ` Matan Azrad
2019-11-12 18:31                             ` Ananyev, Konstantin
2019-11-11 11:15                         ` Ferruh Yigit
2019-11-11 11:33                           ` Matan Azrad
2019-11-11 12:21                             ` Ferruh Yigit
2019-11-11 13:32                               ` Matan Azrad
2019-11-08 13:11                     ` Ananyev, Konstantin
2019-11-08 14:10                       ` Dekel Peled
2019-11-08 14:52                         ` Ananyev, Konstantin
2019-11-08 16:08                           ` Dekel Peled
2019-11-08 16:28                             ` Ananyev, Konstantin
2019-11-09 18:26                               ` Matan Azrad
2019-11-10 22:51                                 ` Ananyev, Konstantin
2019-11-11  6:53                                   ` Matan Azrad
2019-11-07 12:35       ` [dpdk-dev] [PATCH v4 2/3] net/mlx5: use " Dekel Peled
2019-11-08  9:12         ` Slava Ovsiienko
2019-11-08  9:23           ` Ferruh Yigit
2019-11-07 12:35       ` [dpdk-dev] [PATCH v4 3/3] app/testpmd: " Dekel Peled
2019-11-07 14:20         ` Iremonger, Bernard
2019-11-07 20:25         ` Ferruh Yigit
2019-11-08  6:56           ` Matan Azrad
2019-11-08 13:58           ` Dekel Peled
2019-11-08  6:28       ` [dpdk-dev] [PATCH v4 0/3] support " Matan Azrad
2019-11-08 16:42       ` [dpdk-dev] [PATCH v5 " Dekel Peled
2019-11-08 16:42         ` [dpdk-dev] [PATCH v5 1/3] ethdev: " Dekel Peled
2019-11-10 23:07           ` Ananyev, Konstantin
2019-11-11  7:40             ` Dekel Peled
2019-11-08 16:42         ` [dpdk-dev] [PATCH v5 2/3] net/mlx5: use " Dekel Peled
2019-11-08 16:42         ` [dpdk-dev] [PATCH v5 3/3] app/testpmd: " Dekel Peled
2019-11-10 23:11           ` Ananyev, Konstantin
2019-11-11  7:40             ` Dekel Peled
2019-11-08 23:07 ` [dpdk-dev] [PATCH v6] ethdev: add " Thomas Monjalon
2019-11-10 22:47   ` Ananyev, Konstantin
2019-11-11 17:47   ` [dpdk-dev] [PATCH v7 0/3] support API to set " Dekel Peled
2019-11-11 17:47     ` [dpdk-dev] [PATCH v7 1/3] ethdev: " Dekel Peled
2019-11-12  0:46       ` Ferruh Yigit
2019-11-11 17:47     ` [dpdk-dev] [PATCH v7 2/3] net/mlx5: use " Dekel Peled
2019-11-11 17:47     ` [dpdk-dev] [PATCH v7 3/3] app/testpmd: " Dekel Peled
2019-11-12  0:46       ` Ferruh Yigit
2019-11-12  0:47     ` [dpdk-dev] [PATCH v7 0/3] support " Ferruh Yigit

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