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([2a0d:3344:2448:cb10::f39]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a568b090b0sm13845560f8f.46.2025.06.17.05.45.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Jun 2025 05:45:52 -0700 (PDT) Message-ID: <61c54e7b-9ffd-45c4-b37f-c570e310ea45@redhat.com> Date: Tue, 17 Jun 2025 14:45:50 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 5/7] igc: add private flag to reverse TX queue priority in TSN mode To: Vladimir Oltean , Tony Nguyen , Faizal Rahim Cc: faizal.abdul.rahim@intel.com, chwee.lin.choong@intel.com, horms@kernel.org, vitaly.lifshits@intel.com, dima.ruinskiy@intel.com, Mor Bar-Gabay , davem@davemloft.net, edumazet@google.com, andrew+netdev@lunn.ch, netdev@vger.kernel.org, kuba@kernel.org References: <20250611180314.2059166-1-anthony.l.nguyen@intel.com> <20250611180314.2059166-6-anthony.l.nguyen@intel.com> <26b0a6cd-9f2c-487a-bb7a-d648993b8725@redhat.com> <20250617121742.64no35fvb2bbnppf@skbuf> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250617121742.64no35fvb2bbnppf@skbuf> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/17/25 2:17 PM, Vladimir Oltean wrote: > On Tue, Jun 17, 2025 at 12:06:14PM +0200, Paolo Abeni wrote: >> On 6/11/25 8:03 PM, Tony Nguyen wrote: >>> To harmonize TX queue priority behavior between taprio and mqprio, and >>> to fix these issues without breaking long-standing taprio use cases, >>> this patch adds a new private flag, called reverse-tsn-txq-prio, to >>> reverse the TX queue priority. It makes queue 3 the highest and queue 0 >>> the lowest, reusing the TX arbitration logic already used by mqprio. >> Isn't the above quite the opposite of what Vladimir asked in >> https://lore.kernel.org/all/20250214113815.37ttoor3isrt34dg@skbuf/ ? >> >> """ >> I would expect that for uniform behavior, you would force the users a >> little bit to adopt the new TX scheduling mode in taprio, otherwise any >> configuration with preemptible traffic classes would be rejected by the >> driver. >> """ >> >> I don't see him commenting on later version, @Vladimir: does this fits you? > > Indeed, sorry for disappearing from the patch review process. > > I don't see the discrepancy between what Faizal implemented and what we > discussed. Specifically on the bit you quoted - patch "igc: add > preemptible queue support in taprio" refuses taprio schedules with > preemptible TCs if the user hasn't explicitly opted into > IGC_FLAG_TSN_REVERSE_TXQ_PRIO. If that private flag isn't set, > everything works as currently documented, just the new features are > gated. > > The name of the private flag is debatable IMHO, because it's taprio > specific and the name doesn't reflect that (mqprio uses the "reverse" > priority assignment to TX queues by default, and this flag doesn't > change that). Also, "reverse" compared to what? Both operating modes can > equally be named "reverse". Maybe "taprio-standard-txq-priority" would > have been clearer regarding what the flag really does. Anyway, I don't > want to stir up a huge debate around naming if functionality-wise it's > the same thing, they have to maintain it, I don't. > > Is there something I'm missing? It feels like it. I misread your original comment as a request to make the 'standard' priority the default, and the current one reachable only enabling the priv flag. I see you are fine with the current status, so the answer to your question is 'no' ;) Paolo