From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A4B5C77B71 for ; Tue, 25 Apr 2023 11:19:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233708AbjDYLTR (ORCPT ); Tue, 25 Apr 2023 07:19:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233451AbjDYLTQ (ORCPT ); Tue, 25 Apr 2023 07:19:16 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8279B1707; Tue, 25 Apr 2023 04:19:14 -0700 (PDT) Received: from dggpemm500005.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Q5KD93cVDz17XFB; Tue, 25 Apr 2023 19:15:21 +0800 (CST) Received: from [10.69.30.204] (10.69.30.204) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Tue, 25 Apr 2023 19:19:12 +0800 Subject: Re: [PATCH v2 net-next 1/2] net: veth: add page_pool for page recycling To: Maciej Fijalkowski CC: Lorenzo Bianconi , Lorenzo Bianconi , , , , , , , , , , 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> From: Yunsheng Lin Message-ID: <99890c72-eb61-e032-944a-6671d6494c23@huawei.com> Date: Tue, 25 Apr 2023 19:19:12 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.30.204] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2023/4/24 21:10, Maciej Fijalkowski wrote: >>> There was a discussion in the past to reduce XDP_PACKET_HEADROOM to 192B but >>> this is not merged yet and it is not related to this series. We can address >>> your comments in a follow-up patch when XDP_PACKET_HEADROOM series is merged. > > Intel drivers still work just fine at 192 headroom and split the page but > it makes it problematic for BIG TCP where MAX_SKB_FRAGS from shinfo needs I am not sure why we are not enabling skb_shinfo(skb)->frag_list to support BIG TCP instead of increasing MAX_SKB_FRAGS, perhaps there was some disscution about this in the past I am not aware of? > 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_pool > with full 4k page dedicated for a single frame. Can we use header splitting to ensure there is enough tailroom for napi_build_skb() or xdp_frame with shinfo?