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[204.195.112.43]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3adebe9078asm3592937a91.10.2026.10.24.13.47.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 24 Oct 2026 13:47:19 -0700 (PDT) Date: Sat, 24 Oct 2026 13:47:16 -0700 From: Stephen Hemminger To: Marat Khalili Cc: Konstantin Ananyev , Konstantin Ananyev , dev@dpdk.org Subject: Re: [PATCH v2 2/9] bpf: document ethdev callback threading limitations Message-ID: <20261024134716.64470c74@phoenix.local> In-Reply-To: <0309fc87-3912-41b1-8b38-7aa581bf07e3@gmail.com> References: <20261011182158.124246-1-qm2k21@gmail.com> <20261012210917.161343-1-qm2k21@gmail.com> <20261012210917.161343-3-qm2k21@gmail.com> <0309fc87-3912-41b1-8b38-7aa581bf07e3@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Archive: List-Post: List-Help: List-Subscribe: , X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Sat, 24 Oct 2026 15:10:13 +0100 Marat Khalili wrote: > On 19/10/2026 22:10, Konstantin Ananyev wrote: > >> Document the data plane limitation in the file docstring of > >> rte_bpf_ethdev.h: packet callback execution expects only one > >> thread per port/queue pair at a time, making concurrent bursts > >> (such as with RTE_ETH_TX_OFFLOAD_MT_LOCKFREE, shared RX queues, > >> or multi-threaded software PMDs) unsupported. > > Not sure what do you mean by: > > 'shared RX queues' and 'multi-threaded software PMDs'. Can you > > probably clarify? > > I mean any hypothetical solutions that call rx/tx burst concurrently > from multiple threads or processes. To avoid confusion, will just leave > only an RTE_ETH_TX_OFFLOAD_MT_LOCKFREE example in the next version. Other than TX lockfree DPDK is not safe to use rx/tx burst from multiple threads on the same queue. The queue either needs to be bound to a thread, or locking in the application. Many drivers would break if Rx was called concurrently on multiple threads. This design is intentional and one of the reasons DPDK is fast.