Public bug reported:
* Explain the feature
Currently, drivers register to a ct zone that can be shared by multiple
devices. This can be inefficient for the driver to offload, as it
needs to handle all the cases where the tuple can come from,
instead of where it's most likely will arive from.
For example, consider the following tc rules:
tc filter add dev dev1 ... flower action ct commit zone 5 \
action mirred egress redirect dev dev2
tc filter add dev dev2 ... flower action ct zone 5 \
action goto chain chain 2
tc filter add dev dev2 ... flower ct_state +trk+est ... \
action mirred egress redirect dev dev1
Both dev2 and dev1 register to the zone 5 flow table (created
by act_ct). A tuple originating on dev1, going to dev2, will
be offloaded to both devices, and both will need to offload
both directions, resulting in 4 total rules. The traffic
will only hit originiating tuple on dev1, and reply tuple
on dev2.
By passing the originating device that created the connection
with the tuple, dev1 can choose to offload only the originating
tuple, and dev2 only the reply tuple. Resulting in a more
efficient offload.
The first patch adds an act_ct nf conntrack extension, to
temporarily store the originiating device from the skb before
offloading the connection once the connection is established.
Once sent to offload, it fills the tuple originating device.
The second patch get this information from tuples
which pass in openvswitch.
The third patch is Mellanox driver ct offload implementation using
this information to provide a hint to firmware of where this
offloaded tuple packets will arrive from (LOCAL or UPLINK port),
and thus increase insertion rate.
* How to test
Create OVS bridge with 2 devices mlx5 rep devices.
Enable HW offload and configure regular connection tracking OpenFlow rules:
e.g:
ovs-ofctl del-flows br-ovs
ovs-ofctl add-flow br-ovs arp,actions=normal
ovs-ofctl add-flow br-ovs "table=0, ip,ct_state=-trk actions=ct(table=1)"
ovs-ofctl add-flow br-ovs "table=1, ip,ct_state=+trk+new
actions=ct(commit),normal"
ovs-ofctl add-flow br-ovs "table=1, ip,ct_state=+trk+est, actions=normal"
With SW steering enabled and the above commits (and up to date ofed) tuple
insertion rate should be about
twice as fast. This can be seen via procfs hw offloaded count while running
high traffic:
while true; do res=`sudo cat /proc/net/nf_conntrack | grep -i offload` && echo
"$res" && echo "$res" | wc -l; done
* What it could break.
NA
** Affects: linux-bluefield (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1960575
Title:
Pass originating device to drivers offloading ct connection so devices
will filter the tuples and offload them more efficiently
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