Messages in this thread | | | Date | Tue, 14 Mar 2023 09:01:14 +0100 | From | Oleksij Rempel <> | Subject | Re: [PATCH net-next v2 0/2] net: dsa: microchip: tc-ets support |
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On Mon, Mar 13, 2023 at 12:18:33PM -0700, Jakub Kicinski wrote: > On Fri, 10 Mar 2023 10:08:07 +0100 Oleksij Rempel wrote: > > changes v3: > > - add tc_ets_supported to match supported devices > > - dynamically regenerated default TC to queue map. > > - add Acked-by to the first patch > > > > changes v2: > > - run egress limit configuration on all queue separately. Otherwise > > configuration may not apply correctly. > > I thought Vladimir was suggesting mqprio, could you summarize the take > aways from that discussion?
Both Qdiscs are suitable for my use case, but I prefer tc-ets because it aligns better with the abilities of the KSZ9477 family of switches. However, I won't be able to support only the deficit round-robin functionality of tc-ets with this hardware. On the other hand, tc-mqprio has more features that are not supported by this switch, such as TXQ grouping, bandwidth limit, and DCB support. The advanced mapping functionality of tc-mqprio, which involves mapping SO_PRIORITY to TCs and then to TXQ groups, can also be confusing. For my use case, only TC to TXQ mapping is needed.
Futures of tc-mqprio: - all TXQ groups use a strict priority transmission selection algorithm (TSA). Within one TXQ group probably round robin robin TSA is used. - Number of supported traffic classes (TCs) is equal to the number of TXQ groups. - TCs have predefined priorities. TC0 == minimal prio and transmitted last if TCn> TC0 exists. - flexible mapping of all SO_PRIORITYs to TCs - flexible mapping of TCs to TXQ groups. - configurable bandwidth limit per TXQ group.
Futures of tc-ets: - supports strict priority and deficit round robin (DRR) TSA. Both variants can be combined. - quantum of each DRR band can be flexibly configured. - each band has predefined priority and mapped directly to a TXQ. - Supports max 16 TCs. Each TC can be flexibly mapped to a band==TXQ.
Futures of KSZ9477 family: - Supports up to 4 TXQs. LANxxxx variants support up to 8 TXQs - Each TXQ can be configured to strict priority or to weighted round robin (WRR) TSA. - If bandwidth configuration per TXQ is used TSA falls back to simple round robin. - TXQs can’t be grouped without breaking strict priority TSA - Max 8 TCs are supported and can be flexibly mapped to TXQs
Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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