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From: Matan Azrad <matan@mellanox.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	Dekel Peled <dekelp@mellanox.com>,
	"Yigit, Ferruh" <ferruh.yigit@intel.com>,
	"Mcnamara, John" <john.mcnamara@intel.com>,
	"Kovacevic, Marko" <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>,
	"Burakov, Anatoly" <anatoly.burakov@intel.com>,
	"xuanziyang2@huawei.com" <xuanziyang2@huawei.com>,
	"cloud.wangxiaoyun@huawei.com" <cloud.wangxiaoyun@huawei.com>,
	"zhouguoyang@huawei.com" <zhouguoyang@huawei.com>,
	"Lu, Wenzhuo" <wenzhuo.lu@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>,
	"Bie, Tiwei" <tiwei.bie@intel.com>,
	"Wang, Zhihong" <zhihong.wang@intel.com>,
	"yongwang@vmware.com" <yongwang@vmware.com>,
	Thomas Monjalon <thomas@monjalon.net>,
	"arybchenko@solarflare.com" <arybchenko@solarflare.com>,
	"Wu, Jingjing" <jingjing.wu@intel.com>,
	"Iremonger, Bernard" <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: Mon, 11 Nov 2019 06:53:20 +0000
Message-ID: <AM0PR0502MB40198EE98F78DF48C85C2541D2740@AM0PR0502MB4019.eurprd05.prod.outlook.com> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB97725801A8C85779@IRSMSX104.ger.corp.intel.com>


Hi

From: Ananyev, Konstantin
> Hi Matan,
> 
> > > > > > > > > >>>> 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.
> > > > > > >
> > > > > > > So max_rx_pkt_len will remain max size of one packet, while
> > > > > > > max_lro_len will be max accumulate size for each LRO session?
> > > > > > >
> > > > > >
> > > > > > Yes.
> > > > > >
> > > > > > > BTW, I think that for ixgbe max lro is RTE_IPV4_MAX_PKT_LEN.
> > > > > >
> > > > > > Please see my change in drivers/net/ixgbe/ixgbe_ethdev.c.
> > > > > > Change to RTE_IPV4_MAX_PKT_LEN?
> > > > > >
> > > > > > > ixgbe_vf, as I remember, doesn’t support LRO at all.
> > > > > >
> > > > > > Please see my change in
> > > > > > drivers/net/ixgbe/ixgbe_vf_representor.c
> > > > > > Remove it?
> > > > >
> > > > > Yes, please for both.
> > > >
> > > > Will change in v5.
> > > >
> > > > >
> > > > > >
> > > > > > >
> > > > > > > >
> > > > > > > > > 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.
> > > > > > >
> > > > > > > Another question, what will happen if PMD will ignore that
> > > > > > > value and will generate packets bigger then requested?
> > > > > >
> > > > > > PMD should use this value and not ignore it.
> > > > >
> > > > > Hmm, ok but this patch updates mxl driver only...
> > > > > I suppose you expect other PMD maintainers to do the job for
> > > > > their PMDs, right?
> > > > > If so, are they aware (and agree) for this new hard requirement
> > > > > and changes required?
> > > > > Again what PMD should do if it can't support exact value?
> > > > > Let say user asked max_lro_size=20KB but PMD can do only 16KB or
> > > 24KB?
> > > > > Should it fail, or round to smallest, or ...?
> > > > >
> > > > > Actually I wonder, should it really be a hard requirement or
> > > > > more like a guidance to PMD?
> > > > > Why app needs and *exact* value for LRO size?
> > > >
> > > > The exact value should be configured to HW as LRO session limit.
> > >
> > > But if the HW can't support this exact value, see the example above?
> > > In fact, shouldn't we allow PMD to forbid user to configure max LRO size?
> > > Let say if in dev_info max_lro_size==0, then PMD doesn't support LRO
> > > size configuration at all.
> > > That way PMDs who do support LRO, but don't want to (can't to)
> > > support configurable LRO size will stay untouched.
> >
> > Each HW should support packet size limitation no matter if it is LRO packet
> or not:
> > How does the PMD limit the packet size for max rx packet len conf?
> > How does the PMD limit the packet size for the mbuf size?
> 
> Not sure I understand your statement and questions above...
> For sure PMD has to support max_rx_pktlen., but how does it relate to
> max_lro?

You said that HW may not support LRO max size configuration.
I answered that as same as the HW can limit packets to the configuration of max_rx_pkt_len, so it can limit LRO packets size here too.
For simplifications:
Rx Queues which are not configured to do LRO offload should limit their packets to the max_rx_pkt_len field.
Rx Queues which are configured to do LRO offload should limit their packets to the max_lro_pkt_len new field.

In addition, both should limit the packets size to the mbuf size of the Rx mempool configured to the Rx queue( if scatter offload is not enabled).





  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
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 [this message]
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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