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 X-Spam-Level: X-Spam-Status: No, score=-7.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B572C433E0 for ; Thu, 18 Feb 2021 00:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6C0460C41 for ; Thu, 18 Feb 2021 00:47:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230138AbhBRAq4 (ORCPT ); Wed, 17 Feb 2021 19:46:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229803AbhBRAqy (ORCPT ); Wed, 17 Feb 2021 19:46:54 -0500 Received: from mail-il1-x135.google.com (mail-il1-x135.google.com [IPv6:2607:f8b0:4864:20::135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E3CCC061574; Wed, 17 Feb 2021 16:46:14 -0800 (PST) Received: by mail-il1-x135.google.com with SMTP id q9so42615ilo.1; Wed, 17 Feb 2021 16:46:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-transfer-encoding; bh=FIejfxEN+OKZDYsEhrma7B8eOaQBPFZ4Xime0REzBl8=; b=BIOlUGP4CalqxEb+FaqBDN0+Y3g0ppyI7YfN6o54H+4pLr+cllZ4iGI9aTFi1jwTEX HifOemf56cvMLR9/zNW1R0zVcFKF/au3qNbP0oICWnfJxLrGiN1Wr3yj7qq+BoS4hIlh irsXcb9LhYsorTI84JQF8BDXKr489EgtrNjUcr9WYw5odNO1/GprPNH4amxGQvhhDrSx 9h/4q4tm8tHRTGJ0sIGpFl6akHtmFFmIF7YDcXbgSekJH9zhLwwYyIXWvACEKNv8qvPj 3+WV724wqWQ3rnzRRP+PXTBug4ohFcpYHzWCc4zc/IfylYpXTEDiL1vlwDeQ8HI+GFzo fH2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-transfer-encoding; bh=FIejfxEN+OKZDYsEhrma7B8eOaQBPFZ4Xime0REzBl8=; b=GAqAVqQCoCm/pf/1kcd/7ilp/+DWjtYWvju/On8xA8diRKerFPakR6Qia2lb8i9CCY MERFah8FRjL3xAKxO35vkVUVeKHUNPUAsr/i5Yq8WGuDtX6JddGL+jp35vgNRtFFhYF0 kHXdyVIttMl+Z1hovGrGGUL3Ikt114evBeZMkR4WvE3DVXbttmKaXjjFV7wUhjWMH/ak MgT9or6ue6euGsKVqWORfsKUXmJbmF6PGSB4JeVdKjyaMtMi+MCw4EkM29rwDaK3Fo9m 4/+wnBHb2vbvyswHDo2nf0+NX3j80dZXWTJrO8DnL1xS1lciRb4MNilVJRjAA/q/CnDN UZpQ== X-Gm-Message-State: AOAM531GuRf7cI59hUmDGT+TdZDi48/bJgskZtvOyWFmRXOSWT4M0c5O A4hdoJadQkjwubABWzJVHUk= X-Google-Smtp-Source: ABdhPJwDYJNSFnd2wxbwNHFifatEFpaDjjvkV2kZZAVjeyGYGigG85o4rzR5oxz3oajh9p91ZfeP+g== X-Received: by 2002:a05:6e02:2142:: with SMTP id d2mr1492157ilv.249.1613609172754; Wed, 17 Feb 2021 16:46:12 -0800 (PST) Received: from localhost ([172.243.146.206]) by smtp.gmail.com with ESMTPSA id y25sm2902166ioa.5.2021.02.17.16.46.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Feb 2021 16:46:11 -0800 (PST) Date: Wed, 17 Feb 2021 16:46:04 -0800 From: John Fastabend To: Alexander Lobakin , Daniel Borkmann , Magnus Karlsson Cc: "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , Jonathan Lemon , Alexei Starovoitov , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Jesper Dangaard Brouer , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Paolo Abeni , Eric Dumazet , Xuan Zhuo , Dust Li , Alexander Lobakin , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Message-ID: <602db8cc18aaf_fc5420827@john-XPS-13-9370.notmuch> In-Reply-To: <20210217120003.7938-7-alobakin@pm.me> References: <20210217120003.7938-1-alobakin@pm.me> <20210217120003.7938-7-alobakin@pm.me> Subject: RE: [PATCH v7 bpf-next 6/6] xsk: build skb by page (aka generic zerocopy xmit) Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Alexander Lobakin wrote: > From: Xuan Zhuo > > This patch is used to construct skb based on page to save memory copy > overhead. > > This function is implemented based on IFF_TX_SKB_NO_LINEAR. Only the > network card priv_flags supports IFF_TX_SKB_NO_LINEAR will use page to > directly construct skb. If this feature is not supported, it is still > necessary to copy data to construct skb. > > ---------------- Performance Testing ------------ > > The test environment is Aliyun ECS server. > Test cmd: > ``` > xdpsock -i eth0 -t -S -s > ``` > > Test result data: > > size 64 512 1024 1500 > copy 1916747 1775988 1600203 1440054 > page 1974058 1953655 1945463 1904478 > percent 3.0% 10.0% 21.58% 32.3% > > Signed-off-by: Xuan Zhuo > Reviewed-by: Dust Li > [ alobakin: > - expand subject to make it clearer; > - improve skb->truesize calculation; > - reserve some headroom in skb for drivers; > - tailroom is not needed as skb is non-linear ] > Signed-off-by: Alexander Lobakin > Acked-by: Magnus Karlsson > --- [...] > + buffer = xsk_buff_raw_get_data(pool, addr); > + offset = offset_in_page(buffer); > + addr = buffer - pool->addrs; > + > + for (copied = 0, i = 0; copied < len; i++) { > + page = pool->umem->pgs[addr >> PAGE_SHIFT]; Looks like we could walk off the end of pgs[] if len is larger than the number of pgs? Do we need to guard against a misconfigured socket causing a panic here? AFAIU len here is read from the user space descriptor so is under user control. Or maybe I missed a check somewhere. Thanks, John > + get_page(page); > + > + copy = min_t(u32, PAGE_SIZE - offset, len - copied); > + skb_fill_page_desc(skb, i, page, offset, copy); > + > + copied += copy; > + addr += copy; > + offset = 0; > + } > + > + skb->len += len; > + skb->data_len += len; > + skb->truesize += ts; > + > + refcount_add(ts, &xs->sk.sk_wmem_alloc); > + > + return skb; > +} > +