On Tue, Feb 15, 2022 at 8:22 AM Jamal Hadi Salim [off-list ref] wrote:

On 2022-01-26 09:32, xiangxia.m.yue@gmail.com wrote:

quoted

From: Tonghao Zhang <redacted>

This patch allows user to select queue_mapping, range
from A to B. And user can use skbhash, cgroup classid
and cpuid to select Tx queues. Then we can load balance
packets from A to B queue. The range is an unsigned 16bit
value in decimal format.

$ tc filter ... action skbedit queue_mapping skbhash A B

"skbedit queue_mapping QUEUE_MAPPING" (from "man 8 tc-skbedit")
is enhanced with flags:
* SKBEDIT_F_TXQ_SKBHASH
* SKBEDIT_F_TXQ_CLASSID
* SKBEDIT_F_TXQ_CPUID

Use skb->hash, cgroup classid, or cpuid to distribute packets.
Then same range of tx queues can be shared for different flows,
cgroups, or CPUs in a variety of scenarios.

For example, F1 may share range R1 with F2. The best way to do
that is to set flag to SKBEDIT_F_TXQ_HASH, using skb->hash to
share the queues. If cgroup C1 want to share the R1 with cgroup
C2 .. Cn, use the SKBEDIT_F_TXQ_CLASSID. Of course, in some other
scenario, C1 use R1, while Cn can use the Rn.

So while i dont agree that ebpf is the solution for reasons i mentioned
earlier - after looking at the details think iam confused by this change
and maybe i didnt fully understand the use case.

What is the driver that would work  with this?
You said earlier packets are coming out of some pods and then heading to
the wire and you are looking to balance and isolate between bulk and
latency  sensitive traffic - how are any of these metadatum useful for
that? skb->priority seems more natural for that.

Hi
I try to explain. there are two tx-queue range, e.g. A(Q0-Qn), B(Qn+1-Qm).
A is used for latency sensitive traffic. B is used for bulk sensitive
traffic. A may be shared by Pods/Containers which key is
high throughput. B may be shared by Pods/Containers which key is low
latency. So we can do the balance in range A for latency sensitive
traffic.
So we can use the skb->hash or CPUID or classid to classify the
packets in range A or B. The balance policies are used for different
use case.
For skb->hash, the packets from Pods/Containers will share the range.
Should to know that one Pod/Container may use the multi TCP/UDP flows.
That flows share the tx queue range.
For CPUID, while Pod/Container use the multi flows, pod pinned on one
CPU will use one tx-queue in range A or B.
For CLASSID, the Pod may contain the multi containters.

skb->priority may be used by applications. we can't require
application developer to change them.

cheers,
jamal

-- 
Best regards, Tonghao