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 8AD6EC43334 for ; Tue, 28 Jun 2022 19:00:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234834AbiF1TAj (ORCPT ); Tue, 28 Jun 2022 15:00:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233883AbiF1TAU (ORCPT ); Tue, 28 Jun 2022 15:00:20 -0400 Received: from mail-ed1-x536.google.com (mail-ed1-x536.google.com [IPv6:2a00:1450:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79746CE1A; Tue, 28 Jun 2022 11:59:56 -0700 (PDT) Received: by mail-ed1-x536.google.com with SMTP id fd6so18898459edb.5; Tue, 28 Jun 2022 11:59:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=5dH/7z5ivFVO5BHaFYr7Z/XbdA3PCvYtaqkIcRmZ+ew=; b=J3VMvjRE2aCmN5CovG1k5i/yJ77M0VMkQTyWYUV1xWfdD4M+GSgjHsTZEO3QayIdGP lAIaosJGVCaArl4kZy6ut6NvQWWD36X8UkgW3nniv6YbmwT/L93lY9DvPhrFarzh+/oN oTpQJi405WBnmM2UXaKszXT3sMfxkXwh0El8sPfRk9rGVIXAOlytuSr5vPNNwiJvg/Fj UTqmi2guHL9oDdsxKq1+cVVN8Yc33fLp1WtA0CN/sIvz0FqO2yZeWZ0qBrzyAQfakFua 2m1HmBtZ7oHX//Jcmst2HVWUReS8QRpm+HoXDKAIyySHWrEFRAdMWH99zYlyL0ZB2t7M PyiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5dH/7z5ivFVO5BHaFYr7Z/XbdA3PCvYtaqkIcRmZ+ew=; b=W8cSDoiFl9BpeVsPuViBg9FuIOCFteea1QYnvlPQC16B56qm6nHhMzTTW6NKxe5tm/ MnKfukFgbVbxshRYXEqaM+zLRwHWoWCEZOQHp5+3W/CojNj47f7QH/UWZpAOVx9Fqcmk cFGMJrPedxEAcvqxTw2xij14iafzbKZsByQ/hXUY7j1WRPFpp8QPsUwdqwco6QLEgZpB ELzHMEhZi7PSim0LEUX1OJpN5VqDgdRDw/f8YnDXXay6wexOy5IpzdxfSg+aUm58gjeE 9c4+mgflBt/QD0lT8J0EFv5dMfBPtBpM7Qr3A7HdRmTZcbC+Yh3iu12Z8BV5KAfU7Xrd dF+w== X-Gm-Message-State: AJIora8CBBkfudOT7usC06vZeBFPutPk6Zoms+5aFCz2IwmhfHg2NRO0 iUNMwmsIv2OTY3ZP9wDtCj6XcM8Uisos7g== X-Google-Smtp-Source: AGRyM1tzidqJtkS9GbJ51EKbq3+QT82smcW2dq9tUHG5uXnX/7jnNszUnu93omlW5c0CoMGFi7Z/HA== X-Received: by 2002:a05:6402:5388:b0:435:71b:5d44 with SMTP id ew8-20020a056402538800b00435071b5d44mr24524607edb.364.1656442794760; Tue, 28 Jun 2022 11:59:54 -0700 (PDT) Received: from 127.0.0.1localhost (188.28.125.106.threembb.co.uk. [188.28.125.106]) by smtp.gmail.com with ESMTPSA id t21-20020a05640203d500b0043573c59ea0sm9758451edw.90.2022.06.28.11.59.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jun 2022 11:59:54 -0700 (PDT) From: Pavel Begunkov To: io-uring@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "David S . Miller" , Jakub Kicinski , Jonathan Lemon , Willem de Bruijn , Jens Axboe , kernel-team@fb.com, Pavel Begunkov Subject: [RFC net-next v3 02/29] ipv6: avoid partial copy for zc Date: Tue, 28 Jun 2022 19:56:24 +0100 Message-Id: <9806f2103d0c0512155957ee57ead379a11d93bd.1653992701.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.36.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Even when zerocopy transmission is requested and possible, __ip_append_data() will still copy a small chunk of data just because it allocated some extra linear space (e.g. 128 bytes). It wastes CPU cycles on copy and iter manipulations and also misalignes potentially aligned data. Avoid such coies. And as a bonus we can allocate smaller skb. Signed-off-by: Pavel Begunkov --- net/ipv6/ip6_output.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 4081b12a01ff..6103cd9066ff 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1464,6 +1464,7 @@ static int __ip6_append_data(struct sock *sk, int copy; int err; int offset = 0; + bool zc = false; u32 tskey = 0; struct rt6_info *rt = (struct rt6_info *)cork->dst; struct ipv6_txoptions *opt = v6_cork->opt; @@ -1549,6 +1550,7 @@ static int __ip6_append_data(struct sock *sk, if (rt->dst.dev->features & NETIF_F_SG && csummode == CHECKSUM_PARTIAL) { paged = true; + zc = true; } else { uarg->zerocopy = 0; skb_zcopy_set(skb, uarg, &extra_uref); @@ -1630,9 +1632,12 @@ static int __ip6_append_data(struct sock *sk, (fraglen + alloc_extra < SKB_MAX_ALLOC || !(rt->dst.dev->features & NETIF_F_SG))) alloclen = fraglen; - else { + else if (!zc) { alloclen = min_t(int, fraglen, MAX_HEADER); pagedlen = fraglen - alloclen; + } else { + alloclen = fragheaderlen + transhdrlen; + pagedlen = datalen - transhdrlen; } alloclen += alloc_extra; -- 2.36.1