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[194.45.78.10]) by smtp.gmail.com with ESMTPSA id gq15-20020a170906e24f00b00982a92a849asm822836ejb.91.2023.07.27.07.11.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 Jul 2023 07:11:10 -0700 (PDT) From: Jesper Dangaard Brouer X-Google-Original-From: Jesper Dangaard Brouer Message-ID: <50fc375a-27a7-8b6a-3938-f9fcb4f85b06@redhat.com> Date: Thu, 27 Jul 2023 16:11:08 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Cc: brouer@redhat.com, bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, haoluo@google.com, jolsa@kernel.org, kuba@kernel.org, toke@kernel.org, willemb@google.com, dsahern@kernel.org, magnus.karlsson@intel.com, bjorn@kernel.org, maciej.fijalkowski@intel.com, hawk@kernel.org, netdev@vger.kernel.org, xdp-hints@xdp-project.net Subject: Re: [RFC net-next v4 2/8] xsk: add TX timestamp and TX checksum offload support Content-Language: en-US To: Willem de Bruijn , Stanislav Fomichev References: <20230724235957.1953861-1-sdf@google.com> <20230724235957.1953861-3-sdf@google.com> <64c0369eadbd5_3fe1bc2940@willemb.c.googlers.com.notmuch> <64c056686b527_3a4d294e6@willemb.c.googlers.com.notmuch> In-Reply-To: <64c056686b527_3a4d294e6@willemb.c.googlers.com.notmuch> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE, SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On 26/07/2023 01.10, Willem de Bruijn wrote: > Stanislav Fomichev wrote: >> On 07/25, Willem de Bruijn wrote: >>> Stanislav Fomichev wrote: [...] >>>> +struct xsk_tx_metadata { >>>> + __u32 flags; >>>> + >>>> + /* XDP_TX_METADATA_CHECKSUM */ >>>> + >>>> + /* Offset from desc->addr where checksumming should start. */ >>>> + __u16 csum_start; >>>> + /* Offset from csum_start where checksum should be stored. */ >>>> + __u16 csum_offset; >>>> + >>>> + /* XDP_TX_METADATA_TIMESTAMP */ >>>> + >>>> + __u64 tx_timestamp; >>>> +}; >>> >>> Is this structure easily extensible for future offloads, [...] > > Pacing offload is the other feature that comes to mind. That could > conceivably use the tx_timestamp field. I would really like to see hardware offload "pacing" or LaunchTime as hardware chips i210 and i225 calls it. I looked at the TX descriptor details for drivers igc (i225) and igb (i210), and documented my finding here[1], which should help with the code details if someone is motivated for implementing this (I know of people on xdp-hints list that wanted this LaunchTime feature). [1] https://github.com/xdp-project/xdp-project/blob/master/areas/tsn/code01_follow_qdisc_TSN_offload.org#tx-time-to-hardware-driver-igc AFAIK this patchset uses struct xsk_tx_metadata as both TX and TX-Completion, right?. It would be "conceivable" to reuse tx_timestamp field, but it might be confusing for uAPI end-users. Maybe a union? --Jesper