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. -- Adrien Mazarguil 6WIND
