> On Jul 5, 2019, at 11:05 AM, Yongseok Koh <ys...@mellanox.com> wrote: > > > >> On Jul 5, 2019, at 6:54 AM, Adrien Mazarguil <adrien.mazarg...@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 <ys...@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. :-) > > 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]
Adrien, Are you okay with this? Thanks, Yongseok
