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[130.25.106.149]) by smtp.gmail.com with ESMTPSA id c21-20020a7bc855000000b003f17300c7dcsm15023553wml.48.2023.04.25.07.13.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Apr 2023 07:13:08 -0700 (PDT) Date: Tue, 25 Apr 2023 16:13:07 +0200 From: Lorenzo Bianconi To: Yunsheng Lin Cc: Maciej Fijalkowski , Lorenzo Bianconi , netdev@vger.kernel.org, bpf@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, john.fastabend@gmail.com, ast@kernel.org, daniel@iogearbox.net Subject: Re: [PATCH v2 net-next 1/2] net: veth: add page_pool for page recycling Message-ID: References: <6298f73f7cc7391c7c4a52a6a89b1ae21488bda1.1682188837.git.lorenzo@kernel.org> <4f008243-49d0-77aa-0e7f-d20be3a68f3c@huawei.com> <3c78f045-aa8e-22a5-4b38-ab271122a79e@huawei.com> <0c1790dc-dbeb-8664-64ca-1f71e6c4f3a9@huawei.com> <99890c72-eb61-e032-944a-6671d6494c23@huawei.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="CadSs8zlJcx9K3kf" Content-Disposition: inline In-Reply-To: <99890c72-eb61-e032-944a-6671d6494c23@huawei.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org --CadSs8zlJcx9K3kf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > On 2023/4/24 21:10, Maciej Fijalkowski wrote: > >>> There was a discussion in the past to reduce XDP_PACKET_HEADROOM to 1= 92B but > >>> this is not merged yet and it is not related to this series. We can a= ddress > >>> your comments in a follow-up patch when XDP_PACKET_HEADROOM series is= merged. > >=20 > > Intel drivers still work just fine at 192 headroom and split the page b= ut > > it makes it problematic for BIG TCP where MAX_SKB_FRAGS from shinfo nee= ds >=20 > I am not sure why we are not enabling skb_shinfo(skb)->frag_list to suppo= rt > BIG TCP instead of increasing MAX_SKB_FRAGS, perhaps there was some dissc= ution > about this in the past I am not aware of? >=20 > > to be increased. So it's the tailroom that becomes the bottleneck, not = the > > headroom. I believe at some point we will convert our drivers to page_p= ool > > with full 4k page dedicated for a single frame. >=20 > Can we use header splitting to ensure there is enough tailroom for > napi_build_skb() or xdp_frame with shinfo? >=20 since veth_convert_skb_to_xdp_buff() runs in veth_poll() I think we can use napi_build_skb(). I tested it and we get an improvement (9.65Gbps vs 9.2Gbps for 1500B frames). Regards, Lorenzo --CadSs8zlJcx9K3kf Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCZEff8gAKCRA6cBh0uS2t rMbdAQD3WHQe/mjpUtHWLC7RlTGjjTZB2VrCKz6tldyN9wIguQEAsjoeLh830e8k AGbqbbOerSm9+RznSSmS08hoTh5VLQ8= =njoc -----END PGP SIGNATURE----- --CadSs8zlJcx9K3kf--