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Subject: Re: [net-next Patch v2 4/5] octeontx2-pf: Add devlink support to
 configure TL1 RR_PRIO
Thread-Topic: [net-next Patch v2 4/5] octeontx2-pf: Add devlink support to
 configure TL1 RR_PRIO
Thread-Index: AQHZLKw3Ph/wPlV6p0Cw/IyBaankiA==
Date:   Fri, 20 Jan 2023 08:50:16 +0000
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On Wed, Jan 18, 2023 at 04:21:06PM +0530, Hariprasad Kelam wrote:
> All VFs and PF netdev shares same TL1 schedular, each interface PF or=20
> VF will have different TL2 schedulars having same parent TL1. The TL1=20
> RR_PRIO value is static and PF/VFs use the same value to configure its=20
> TL2 node priority in case of DWRR children.
>=20
> This patch adds support to configure TL1 RR_PRIO value using devlink.
> The TL1 RR_PRIO can be configured for each PF. The VFs are not allowed=20
> to configure TL1 RR_PRIO value. The VFs can get the RR_PRIO value from=20
> the mailbox NIX_TXSCH_ALLOC response parameter aggr_lvl_rr_prio.

I asked this question under v1, but didn't get an answer, could you shed so=
me light?

"Could you please elaborate how these priorities of Transmit Levels are rel=
ated to HTB priorities? I don't seem to understand why something has to be =
configured with devlink in addition to HTB.

SMQ (send meta-descriptor queue) and MDQ (meta-descriptor queue) are the fi=
rst transmit levels.
Each send queue is mapped with SMQ.
=20
As mentioned in cover letter, each egress packet needs to traverse all tran=
smit levels starting from TL5 to TL1.
This applies to non-QOS Send queues as well.
=20
                       SMQ/MDQ --> TL4 -->TL3 -->TL2 -->TL1

By default non QOS queues use a default hierarchy  with round robin priorit=
y.=20
To avoid conflict with QOS tree priorities, with devlink user can choose ro=
und-robin priority before Qos tree formation.


BTW, why did you remove the paragraphs with an example and a limitation?
I think they are pretty useful.

Ok , removed them accidentally will correct in the next version.

Another question unanswered under v1 was:

"Is there any technical difficulty or hardware limitation preventing from i=
mplementing modifications?" (TC_HTB_NODE_MODIFY)

There is no hardware limitation, we are currently implementing it.  once it=
's implemented we will submit for review.