On 6/10/19 6:19 AM, Wang, Haiyue wrote:
-----Original Message-----
From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Andrew Rybchenko
Sent: Sunday, June 9, 2019 22:24
To: Yongseok Koh <ys...@mellanox.com>; shah...@mellanox.com;
tho...@monjalon.net; Yigit, Ferruh
<ferruh.yi...@intel.com>; adrien.mazarg...@6wind.com; olivier.m...@6wind.com
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [RFC 1/3] ethdev: extend flow metadata
On 6/4/19 12:32 AM, Yongseok Koh wrote:
Currently, metadata can be set on egress path via mbuf tx_meatadata field
with PKT_TX_METADATA flag and RTE_FLOW_ITEM_TYPE_RX_META matches metadata.
This patch extends the usability.
1) RTE_FLOW_ACTION_TYPE_SET_META
When supporting multiple tables, Tx metadata can also be set by a rule and
matched by another rule. This new action allows metadata to be set as a
result of flow match.
2) Metadata on ingress
There's also need to support metadata on packet Rx. Metadata can be set by
SET_META action and matched by META item like Tx. The final value set by
the action will be delivered to application via mbuf metadata field with
PKT_RX_METADATA ol_flag.
For this purpose, mbuf->tx_metadata is moved as a separate new field and
renamed to 'metadata' to support both Rx and Tx metadata.
For loopback/hairpin packet, metadata set on Rx/Tx may or may not be
propagated to the other path depending on HW capability.
Signed-off-by: Yongseok Koh <ys...@mellanox.com>
There is a mark on Rx which is delivered to application in hash.fdir.hi.
Why do we need one more 32-bit value set by NIC and delivered to
application?
What is the difference between MARK and META on Rx?
When application should use MARK and when META?
Is there cases when both could be necessary?
In my understanding, MARK is FDIR related thing, META seems to be NIC
specific. And we also need this kind of specific data field to export
NIC's data to application.
I think it is better to avoid NIC vendor-specifics in motivation. I
understand
that it exists for you, but I think it is better to look at it from RTE
flow API
definition point of view: both are 32-bit (except endianess and I'm not sure
that I understand why meta is defined as big-endian since it is not a value
coming from or going to network in a packet, I'm sorry that I've missed it
on review that time), both may be set using action on Rx, both may be
matched using pattern item.
Moreover, the third patch adds 32-bit tags which are not delivered to
application. May be META/MARK should be simply a kind of TAG (e.g. with
index 0 or marked using additional attribute) which is delivered to
application?
(It is either API breakage (if tx_metadata is removed) or ABI breakage
if metadata and tx_metadata will share new location after shinfo).
Make use of udata64 to export NIC metadata to application ?
RTE_STD_C11
union {
void *userdata; /**< Can be used for external metadata */
uint64_t udata64; /**< Allow 8-byte userdata on 32-bit */
uint64_t rx_metadata;
};
As I understand it does not work for Tx and I'm not sure that it is
a good idea to have different locations for Tx and Rx.
RFC adds it at the end of mbuf, but it was rejected before since
it eats space in mbuf structure (CC Konstantin).
There is a long discussion on the topic before [1], [2], [3] and [4].
Andrew.
[1] http://mails.dpdk.org/archives/dev/2018-August/109660.html
[2] http://mails.dpdk.org/archives/dev/2018-September/111771.html
[3] http://mails.dpdk.org/archives/dev/2018-October/114559.html
[4] http://mails.dpdk.org/archives/dev/2018-October/115469.html
