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 896B0C433EF for ; Tue, 12 Jul 2022 20:53:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233861AbiGLUxO (ORCPT ); Tue, 12 Jul 2022 16:53:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233817AbiGLUxM (ORCPT ); Tue, 12 Jul 2022 16:53:12 -0400 Received: from mail-wr1-x42d.google.com (mail-wr1-x42d.google.com [IPv6:2a00:1450:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56E30CC782; Tue, 12 Jul 2022 13:53:11 -0700 (PDT) Received: by mail-wr1-x42d.google.com with SMTP id bu1so11641570wrb.9; Tue, 12 Jul 2022 13:53:11 -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=SL5QCbmxRVN2Iu3K+3SZdBj/leE9bYZIxrF5QeizLlc=; b=n2thYeKr1uORHjbkNzteTnpKgpMfvug7+zTbObHML5qGqLzY/C76gISJd97CDl9Mkn scpOuGyeZ85AjsqLKzk+4x3fde+ddmn67ONyKs1lX6ng9dieMxDnO6Jlmj68hP5nkG/D UX6x1xewtQz1GheammHBKTR53Gr8Sp48DR4ldG2anG0RGTKEshpyA9eHatOTlLMv2QSJ qVDaYNzhDU1ck6qRHPjyn+UyS2h9JfKFoS9yGNeMzZuOYJoGX6WG7xGV9Avc/BelRW3e v5HXg6EPFzTTznI94rawQuANyEYRZHQz8D491zACb3GcjV25F7wdC2pOWM6Mmm8g83PK aPhw== 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=SL5QCbmxRVN2Iu3K+3SZdBj/leE9bYZIxrF5QeizLlc=; b=FVtr4g4mEtmjRapYaoIDb/PoofCVsRsKbOOJWd79a+ne4vQbswxVUPC+a7iw7Cl1kJ Pg/j9fGlKH3F9Bgp2YgN/TUBuOdPpZqWItmzAR2xy1VcEeGq87pxSz0tRyG2RI6cjz87 feiT57JUaYUF1bdRqze7PBnRrhy4SvKrP8apD6FRrYs4pqjuzZ89bMen12pheSTmMVCO M0PC2fwtIpB/QDE6m4rOsDhbtGVu9EugkCNUezObp0/Ed2m17gBa6Dfd1MhAPwKZK8fc A0bgMPWTyP1lS0P/M7+PDwd30cE8a/V9ejHbzXQweqTeqvVPS7vbxJ4p+n//hdO/XFgM mEHw== X-Gm-Message-State: AJIora9WK2nCAh2J7giquJMoh+i7yo4fPQ4eBGTMg+kJ5edGzzHhdxOu 3JSvzgI4zl0nqNr8roON/EqyDQwyfSw= X-Google-Smtp-Source: AGRyM1v5hj1bXBu/gKqNE7Gnj+j+mM/0mepgtXvGc0RMujzfF+eMeQfJNyizw0zNBg1PWLKXYRRQMg== X-Received: by 2002:a5d:588b:0:b0:21d:a918:65a5 with SMTP id n11-20020a5d588b000000b0021da91865a5mr10606510wrf.210.1657659189643; Tue, 12 Jul 2022 13:53:09 -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 c14-20020a7bc00e000000b003a044fe7fe7sm89833wmb.9.2022.07.12.13.53.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Jul 2022 13:53:09 -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 , David Ahern , kernel-team@fb.com, Pavel Begunkov Subject: [PATCH net-next v5 02/27] ipv6: avoid partial copy for zc Date: Tue, 12 Jul 2022 21:52:26 +0100 Message-Id: <899f19034c94ce4ce75464df132edf1b3a192ebd.1657643355.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.37.0 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 77e3f5970ce4..fc74ce3ed8cc 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; -- 2.37.0