From: Adrien Mazarguil <adrien.mazarguil@6wind.com>
To: Yongseok Koh <yskoh@mellanox.com>
Cc: Shahaf Shuler <shahafs@mellanox.com>,
Thomas Monjalon <thomas@monjalon.net>,
Ferruh Yigit <ferruh.yigit@intel.com>,
Andrew Rybchenko <arybchenko@solarflare.com>,
Olivier Matz <olivier.matz@6wind.com>, dev <dev@dpdk.org>,
Slava Ovsiienko <viacheslavo@mellanox.com>
Subject: Re: [dpdk-dev] [PATCH] ethdev: add flow tag
Date: Tue, 9 Jul 2019 10:38:06 +0200 [thread overview]
Message-ID: <20190709083806.GS4512@6wind.com> (raw)
In-Reply-To: <6EE319CD-4BBC-47BF-AAE5-2165B8C1D491@mellanox.com>
On Fri, Jul 05, 2019 at 06:05:50PM +0000, Yongseok Koh wrote:
> > On Jul 5, 2019, at 6:54 AM, Adrien Mazarguil <adrien.mazarguil@6wind.com> wrote:
> >
> > On Thu, Jul 04, 2019 at 04:23:02PM -0700, Yongseok Koh wrote:
> >> A tag is a transient data which can be used during flow match. This can be
> >> used to store match result from a previous table so that the same pattern
> >> need not be matched again on the next table. Even if outer header is
> >> decapsulated on the previous match, the match result can be kept.
> >>
> >> Some device expose internal registers of its flow processing pipeline and
> >> those registers are quite useful for stateful connection tracking as it
> >> keeps status of flow matching. Multiple tags are supported by specifying
> >> index.
> >>
> >> Example testpmd commands are:
> >>
> >> flow create 0 ingress pattern ... / end
> >> actions set_tag index 2 value 0xaa00bb mask 0xffff00ff /
> >> set_tag index 3 value 0x123456 mask 0xffffff /
> >> vxlan_decap / jump group 1 / end
> >>
> >> flow create 0 ingress pattern ... / end
> >> actions set_tag index 2 value 0xcc00 mask 0xff00 /
> >> set_tag index 3 value 0x123456 mask 0xffffff /
> >> vxlan_decap / jump group 1 / end
> >>
> >> flow create 0 ingress group 1
> >> pattern tag index is 2 value spec 0xaa00bb value mask 0xffff00ff /
> >> eth ... / end
> >> actions ... jump group 2 / end
> >>
> >> flow create 0 ingress group 1
> >> pattern tag index is 2 value spec 0xcc00 value mask 0xff00 /
> >> tag index is 3 value spec 0x123456 value mask 0xffffff /
> >> eth ... / end
> >> actions ... / end
> >>
> >> flow create 0 ingress group 2
> >> pattern tag index is 3 value spec 0x123456 value mask 0xffffff /
> >> eth ... / end
> >> actions ... / end
> >>
> >> Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
> >
> > Hi Yongseok,
> >
> > Only high level questions for now, while it unquestionably looks useful,
> > from a user standpoint exposing the separate index seems redundant and not
> > necessarily convenient. Using the following example to illustrate:
> >
> > actions set_tag index 3 value 0x123456 mask 0xfffff
> >
> > pattern tag index is 3 value spec 0x123456 value mask 0xffffff
> >
> > I might be missing something, but why isn't this enough:
> >
> > pattern tag index is 3 # match whatever is stored at index 3
> >
> > Assuming it can work, then why bother with providing value spec/mask on
> > set_tag? A flow rule pattern matches something, sets some arbitrary tag to
> > be matched by a subsequent flow rule and that's it. It even seems like
> > relying on the index only on both occasions is enough for identification.
> >
> > Same question for the opposite approach; relying on the value, never
> > mentioning the index.
> >
> > I'm under the impression that the index is a hardware-specific constraint
> > that shouldn't be exposed (especially since it's an 8-bit field). If so, a
> > PMD could keep track of used indices without having them exposed through the
> > public API.
>
>
> Thank you for review, Adrien.
> Hope you are doing well. It's been long since we talked each other. :-)
Yeah clearly! Hope you're doing well too. I'm somewhat busy hence slow to
answer these days...
<dev@dpdk.org> hey!
<dev@dpdk.org> no private talks!
Back to the topic:
> Your approach will work too in general but we have a request from customer that
> they want to partition this limited tag storage. Assuming that HW exposes 32bit
> tags (those are 'registers' in HW pipeline in mlx5 HW). Then, customers want to
> store multiple data even in a 32-bit storage. For example, 16bit vlan tag, 8bit
> table id and 8bit flow id. As they want to split one 32bit storage, I thought it
> is better to provide mask when setting/matching the value. Even some customer
> wants to store multiple flags bit by bit like ol_flags. They do want to alter
> only partial bits.
>
> And for the index, it is to reference an entry of tags array as HW can provide
> larger registers than 32-bit. For example, mlx5 HW would provide 4 of 32b
> storage which users can use for their own sake.
> tag[0], tag[1], tag[2], tag[3]
OK, looks like I missed the point then. I initially took it for a funky
alternative to RTE_FLOW_ITEM_TYPE_META & RTE_FLOW_ACTION_TYPE_SET_META
(ingress extended [1]) but while it could be used like that, it's more of a
way to temporarily store and retrieve a small amount of data, correct?
Out of curiosity, are these registers independent from META and other
items/actions in mlx5, otherwise what happens if they are combined?
Are there other uses for these registers? Say, referencing their contents
from other places in a flow rule so they don't have to be hard-coded?
Right now I'm still uncomfortable with such a feature in the public API
because compared to META [1], this approach looks very hardware-specific and
seemingly difficult to map on different HW architectures.
However, the main problem is that as described, its end purpose seems
redundant with META, which I think can cover the use cases you gave. So what
can an application do with this that couldn't be done in a more generic
fashion through META?
I may still be missing something and I'm open to ideas, but assuming it
doesn't make it into the public rte_flow API, it remains an interesting
feature on its own merit which could be added to DPDK as PMD-specific
pattern items/actions [2]. mlx5 doesn't have any yet, but it's pretty common
for PMDs to expose a public header that dedicated applications can include
to use this kind of features (look for rte_pmd_*.h, e.g. rte_pmd_ixgbe.h).
No problem with that.
[1] "[PATCH] ethdev: extend flow metadata"
https://mails.dpdk.org/archives/dev/2019-July/137305.html
[2] "Negative types"
https://doc.dpdk.org/guides/prog_guide/rte_flow.html#negative-types
--
Adrien Mazarguil
6WIND
next prev parent reply other threads:[~2019-07-09 8:38 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-03 21:32 [dpdk-dev] [RFC 1/3] ethdev: extend flow metadata Yongseok Koh
2019-06-03 21:32 ` [dpdk-dev] [RFC 2/3] ethdev: add flow modify mark action Yongseok Koh
2019-06-06 10:35 ` Jerin Jacob Kollanukkaran
2019-06-06 18:33 ` Yongseok Koh
2019-06-03 21:32 ` [dpdk-dev] [RFC 3/3] ethdev: add flow tag Yongseok Koh
2019-07-04 23:23 ` [dpdk-dev] [PATCH] " Yongseok Koh
2019-07-05 13:54 ` Adrien Mazarguil
2019-07-05 18:05 ` Yongseok Koh
2019-07-08 23:32 ` Yongseok Koh
2019-07-09 8:38 ` Adrien Mazarguil [this message]
2019-07-11 1:59 ` Yongseok Koh
2019-10-08 12:57 ` Yigit, Ferruh
2019-10-08 13:18 ` Slava Ovsiienko
2019-10-10 16:09 ` [dpdk-dev] [PATCH v2] " Viacheslav Ovsiienko
2019-10-24 13:12 ` [dpdk-dev] [PATCH v3] " Viacheslav Ovsiienko
2019-10-27 16:38 ` Ori Kam
2019-10-27 18:42 ` [dpdk-dev] [PATCH v4] " Viacheslav Ovsiienko
2019-10-27 19:11 ` Ori Kam
2019-10-31 18:57 ` Ferruh Yigit
2019-06-09 14:23 ` [dpdk-dev] [RFC 1/3] ethdev: extend flow metadata Andrew Rybchenko
2019-06-10 3:19 ` Wang, Haiyue
2019-06-10 7:20 ` Andrew Rybchenko
2019-06-11 0:06 ` Yongseok Koh
2019-06-19 9:05 ` Andrew Rybchenko
2019-07-04 23:21 ` [dpdk-dev] [PATCH] " Yongseok Koh
2019-07-10 9:31 ` Olivier Matz
2019-07-10 9:55 ` Bruce Richardson
2019-07-10 10:07 ` Olivier Matz
2019-07-10 12:01 ` Bruce Richardson
2019-07-10 12:26 ` Thomas Monjalon
2019-07-10 16:37 ` Yongseok Koh
2019-07-11 7:44 ` Adrien Mazarguil
2019-07-14 11:46 ` Andrew Rybchenko
2019-07-29 15:06 ` Adrien Mazarguil
2019-10-08 12:51 ` Yigit, Ferruh
2019-10-08 13:17 ` Slava Ovsiienko
2019-10-10 16:02 ` [dpdk-dev] [PATCH v2] " Viacheslav Ovsiienko
2019-10-18 9:22 ` Olivier Matz
2019-10-19 19:47 ` Slava Ovsiienko
2019-10-21 16:37 ` Olivier Matz
2019-10-24 6:49 ` Slava Ovsiienko
2019-10-24 9:22 ` Olivier Matz
2019-10-24 12:30 ` Slava Ovsiienko
2019-10-24 13:08 ` [dpdk-dev] [PATCH v3] " Viacheslav Ovsiienko
2019-10-27 16:56 ` Ori Kam
2019-10-27 18:40 ` [dpdk-dev] [PATCH v4] " Viacheslav Ovsiienko
2019-10-27 19:10 ` Ori Kam
2019-10-29 16:22 ` Andrew Rybchenko
2019-10-29 17:19 ` Slava Ovsiienko
2019-10-29 18:30 ` Thomas Monjalon
2019-10-29 18:35 ` Slava Ovsiienko
2019-10-30 6:28 ` Andrew Rybchenko
2019-10-30 7:35 ` Andrew Rybchenko
2019-10-30 8:59 ` Slava Ovsiienko
2019-10-30 9:20 ` Andrew Rybchenko
2019-10-30 10:05 ` Slava Ovsiienko
2019-10-30 10:03 ` Slava Ovsiienko
2019-10-30 15:49 ` Olivier Matz
2019-10-31 9:25 ` Andrew Rybchenko
2019-10-29 16:25 ` Olivier Matz
2019-10-29 16:33 ` Olivier Matz
2019-10-29 17:53 ` Slava Ovsiienko
2019-10-29 17:43 ` Slava Ovsiienko
2019-10-29 19:31 ` [dpdk-dev] [PATCH v5] " Viacheslav Ovsiienko
2019-10-30 8:02 ` Andrew Rybchenko
2019-10-30 14:40 ` Slava Ovsiienko
2019-10-30 14:46 ` Slava Ovsiienko
2019-10-30 15:20 ` Olivier Matz
2019-10-30 15:57 ` Thomas Monjalon
2019-10-30 15:58 ` Slava Ovsiienko
2019-10-30 16:13 ` Olivier Matz
2019-10-30 8:35 ` Ori Kam
2019-10-30 17:12 ` [dpdk-dev] [PATCH v6 0/2] extend flow metadata feature Viacheslav Ovsiienko
2019-10-30 17:12 ` [dpdk-dev] [PATCH v6 1/2] ethdev: extend flow metadata Viacheslav Ovsiienko
2019-10-31 9:19 ` Andrew Rybchenko
2019-10-31 13:05 ` [dpdk-dev] [PATCH v7 0/2] extend flow metadata feature Viacheslav Ovsiienko
2019-10-31 13:05 ` [dpdk-dev] [PATCH v7 1/2] ethdev: extend flow metadata Viacheslav Ovsiienko
2019-10-31 15:47 ` Olivier Matz
2019-10-31 16:13 ` Slava Ovsiienko
2019-10-31 16:48 ` [dpdk-dev] [PATCH v8 0/2] extend flow metadata feature Viacheslav Ovsiienko
2019-10-31 16:48 ` [dpdk-dev] [PATCH v8 1/2] ethdev: extend flow metadata Viacheslav Ovsiienko
2019-11-04 6:13 ` [dpdk-dev] [PATCH v9 0/2] extend flow metadata feature Viacheslav Ovsiienko
2019-11-04 6:13 ` [dpdk-dev] [PATCH v9 1/2] ethdev: extend flow metadata Viacheslav Ovsiienko
2019-11-05 14:19 ` [dpdk-dev] [PATCH v10 0/2] extend flow metadata feature Viacheslav Ovsiienko
2019-11-05 14:19 ` [dpdk-dev] [PATCH v10 1/2] ethdev: extend flow metadata Viacheslav Ovsiienko
2019-11-05 14:19 ` [dpdk-dev] [PATCH v10 2/2] ethdev: move egress metadata to dynamic field Viacheslav Ovsiienko
2019-11-06 15:49 ` [dpdk-dev] [PATCH v10 0/2] extend flow metadata feature Ferruh Yigit
2019-11-04 6:13 ` [dpdk-dev] [PATCH v9 2/2] ethdev: move egress metadata to dynamic field Viacheslav Ovsiienko
2019-10-31 16:48 ` [dpdk-dev] [PATCH v8 " Viacheslav Ovsiienko
2019-10-31 17:21 ` Olivier Matz
2019-11-01 12:34 ` Andrew Rybchenko
2019-10-31 13:05 ` [dpdk-dev] [PATCH v7 " Viacheslav Ovsiienko
2019-10-31 13:33 ` Ori Kam
2019-10-31 15:51 ` Olivier Matz
2019-10-31 16:07 ` Slava Ovsiienko
2019-10-30 17:12 ` [dpdk-dev] [PATCH v6 " Viacheslav Ovsiienko
2019-10-31 9:01 ` Andrew Rybchenko
2019-10-31 10:54 ` Slava Ovsiienko
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