From patchwork Tue Dec 21 15:35:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Begunkov X-Patchwork-Id: 12689977 X-Patchwork-Delegate: kuba@kernel.org 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 C5CF4C4332F for ; Tue, 21 Dec 2021 15:36:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239506AbhLUPgS (ORCPT ); Tue, 21 Dec 2021 10:36:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33684 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239457AbhLUPgC (ORCPT ); Tue, 21 Dec 2021 10:36:02 -0500 Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26737C061574; Tue, 21 Dec 2021 07:36:02 -0800 (PST) Received: by mail-wr1-x431.google.com with SMTP id i22so27665272wrb.13; Tue, 21 Dec 2021 07:36:02 -0800 (PST) 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=wvTIec5KLzRjZYzsXsnhjT/wGUOjwWKFs3BDJ+O8UAE=; b=hCcv/uDRlbmGmkA/NE6LfCieO1Yf2GBtgbfiZAjTpUxrTVhAyiVdL2a8heQ+oxL0dK minxvJpIAn6TpIKSRvxdIxpma9g7QeefXOrfLJiVenmw+spBmz8ZQD5s8Y4Pf8ZkB59L bc6caKqxhneP0YenwHdicbsHo4fw+9LefkU2ZdoKlBLJAXdz43/ik08uvJcvoCnl/tO4 yC2m1/0Od3wOmZDrc1gM1tFLeCkDjoOrnWFFxEJgA8szVcrxfEe2PdVAsAxZ+OZgTJJn NGPH0DqOjVJwMpF4Xycc/uBhGa74SUx1PD0ywv8rQkY25vzeREV3EeR6tNEjdyq0RmjS zRpw== 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=wvTIec5KLzRjZYzsXsnhjT/wGUOjwWKFs3BDJ+O8UAE=; b=oCKYGtQGk4SNvf1msIMlpY+YCnQqnuGcVk+2gpE3NfVEz9YNgKfzZ7b8/fq3jf2lOb I6GezkIU/22GN1y7fW0A27YBYEfM19BGFVsG34Uv9vZyWM8TVJfBzUUXijpZ7UROLjO/ 7U5VZBFueJDSzx1pWNHjV1lKIeUnUssHwO9+Ow3WCKRkoZvKtgrnZ6MpTb9xDbka2rrV 4Ag77l1vsNzbltHHvZA+5l75Zj9FG32IfYXhW864OGEVdSIoCFKwE30BPaFgrL0HPD41 Maofwjhxo/EirlTMMxzFCPvkkZtqR9ZT6qIZWqR9GLGxgY7daOTGQnGOw9fbMjRcI9Fi iKUQ== X-Gm-Message-State: AOAM530AV79PbffFYBheM9iehn3IM61Xq9ykdZ1u6W8lAmjT9J/kUoC7 x3ALOlSMiNmzD4K7MoBa1+mYhHbiSlg= X-Google-Smtp-Source: ABdhPJzy6vgnm90jvtv4pJn4T+wvd+XYnsTzspBiHMYfM2IONkCjPkOO7qBgMBufSCuCx+H6ylJeyg== X-Received: by 2002:adf:80c2:: with SMTP id 60mr3103274wrl.609.1640100960583; Tue, 21 Dec 2021 07:36:00 -0800 (PST) Received: from 127.0.0.1localhost ([148.252.128.24]) by smtp.gmail.com with ESMTPSA id z11sm2946019wmf.9.2021.12.21.07.35.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Dec 2021 07:36:00 -0800 (PST) From: Pavel Begunkov To: io-uring@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jakub Kicinski , Jonathan Lemon , "David S . Miller" , Willem de Bruijn , Eric Dumazet , David Ahern , Jens Axboe , Pavel Begunkov Subject: [RFC v2 08/19] ipv4: avoid partial copy for zc Date: Tue, 21 Dec 2021 15:35:30 +0000 Message-Id: <4c2bf8d68ffa06b212c9a4a4a095787fbdf05eb7.1640029579.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC 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. 148 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/ipv4/ip_output.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index f820288092ab..5ec9e540a660 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1095,9 +1095,12 @@ static int __ip_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;