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Thu, 25 Sep 2025 03:18:51 -0700 (PDT) From: Jakub Sitnicki To: Mehdi Ben Hadj Khelifa Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, donald.hunter@gmail.com, andrew+netdev@lunn.ch, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, matttbe@kernel.org, chuck.lever@oracle.com, jdamato@fastly.com, skhawaja@google.com, dw@davidwei.uk, mkarsten@uwaterloo.ca, yoong.siang.song@intel.com, david.hunter.linux@gmail.com, skhan@linuxfoundation.org, horms@kernel.org, sdf@fomichev.me, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: Re: [PATCH RFC 0/4] Add XDP RX queue index metadata via kfuncs In-Reply-To: <0cddb596-a70b-48d4-9d8e-c6cb76abd9d2@gmail.com> (Mehdi Ben Hadj Khelifa's message of "Thu, 25 Sep 2025 11:54:59 +0100") References: <20250923210026.3870-1-mehdi.benhadjkhelifa@gmail.com> <87h5wq50l0.fsf@cloudflare.com> <0cddb596-a70b-48d4-9d8e-c6cb76abd9d2@gmail.com> Date: Thu, 25 Sep 2025 12:18:50 +0200 Message-ID: <87348a4yyd.fsf@cloudflare.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Sep 25, 2025 at 11:54 AM +01, Mehdi Ben Hadj Khelifa wrote: > On 9/25/25 10:43 AM, Jakub Sitnicki wrote: >> On Tue, Sep 23, 2025 at 10:00 PM +01, Mehdi Ben Hadj Khelifa wrote: >>> This patch series is intended to make a base for setting >>> queue_index in the xdp_rxq_info struct in bpf/cpumap.c to >>> the right index. Although that part I still didn't figure >>> out yet,I m searching for my guidance to do that as well >>> as for the correctness of the patches in this series. >> What is the use case/movtivation behind this work? > > The goal of the work is to have xdp programs have the correct packet RX queue > index after being redirected through cpumap because currently the queue_index > gets unset or more accurately set to 0 as a default in xdp_rxq_info. This is my > current understanding.I still have to know how I can propogate that HW hint from > the NICs to the function where I need it. This explains what this series does, the desired end state of information passing, but not why is does it - how that information is going to be consumed? To what end? I'd start by figuring that part out. Otherwise you're just proposing adding code that serves no actual purpose.