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[2003:ea:8f29:d400:ad48:a70e:f06d:ba53]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43b647120a1sm4209742f8f.30.2026.03.20.00.01.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Mar 2026 00:01:06 -0700 (PDT) Message-ID: Date: Fri, 20 Mar 2026 08:01:05 +0100 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: r8169: Discussion on implementing RSS support for r8169 To: Javen Cc: "andrew+netdev@lunn.ch" , "davem@davemloft.net" , "edumazet@google.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "horms@kernel.org" , "netdev@vger.kernel.org" References: <1ce3478d571f4d26a45e792c4c84c429@realsil.com.cn> <86784e19c4504c3ba49a9299701a2c1f@realsil.com.cn> Content-Language: en-US From: Heiner Kallweit In-Reply-To: <86784e19c4504c3ba49a9299701a2c1f@realsil.com.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 20.03.2026 04:22, Javen wrote: >> On 19.03.2026 09:56, Javen wrote: >>> Hi, Heiner >>> >>> We are now planning to implement RSS support on r8169 driver. This will >> require significant changes to the existing driver architecture, so we want to >> discuss it with you. >>> >> Thanks for the question. >> I also once considered this, but decided against it, as I didn't see enough >> benefit justifying the significantly increased complexity of the driver. Even >> with a N100-based mini-pc I can easily saturate a 2.5Gbps link with the driver >> as-is. >> Any specific reason why you consider adding RSS support? Would be good to >> see a performance comparison as basis for a decision on for which chip >> versions RSS may provide a significant benefit. >> > > The primary beneft of adding rss here is to reduce cpu load per core. > > Since I currently only have one RTL8111ep and one RTL8127, I'm going to do a simple test. > > Based on my iperf test from RTL8111ep to RTL8127: > 1. With rss: cpu load is distributed across 4 cores(1% ~ 2% each) > 2. Without rss: cpu load is concentrated on a single core(7% ~ 8%) > In sum it's the same, so we don't gain anything. More the opposite, we keep more CPU's busy and don't allow them to transition to deeper power-saving states. > If test from RTL8127 to RTL8127, especially on platforms with weaker cpu, disabling rss will easily lead to cpu overload. I could imagine this at a rate of 10Gbps, but still would like to see some numbers. However, question is how realistic are use cases where a 10Gbps link is used (and fully utilized) on a system with a weak cpu. > That's the main reason we consider adding rss support for RTL8127. > > I will show the result from RTL8127 to RTL8127 when I submit rss patch. > Yes, please. > Thanks, > Javen Xu > >>> Based on our vendor driver which can be fetched from Realtek, the key >> modifications will include: >>> >>> 1. Enable msix and updating the irq allocation mechanism >>> 2. Support multiple rx/tx queues >>> 3. Register multiple napi and update new interrupt mapping(isr/imr) for >> multi-queue >>> 4. Implement rx msix poll and rx interrupt function >>> 5. Implement ethtool callbacks for rss configuration >>> >>> Should we submit the changes above separately or submit them all at once? >> Or do you have any other suggestions? >>> >> As Andrew already said, please submit the patches in smaller, reviewable, >> chunks. >> Best tagged as RFC. >> >>> We want to align with you on the development and submission approach. >>> >>> Best regards, >>> >>> Javen Xu >> >> Heiner