From patchwork Wed Dec 2 22:09:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arjun Roy X-Patchwork-Id: 337598 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=-10.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 5F4D3C64E7C for ; Wed, 2 Dec 2020 22:11:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07E9221D7A for ; Wed, 2 Dec 2020 22:11:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387488AbgLBWLB (ORCPT ); Wed, 2 Dec 2020 17:11:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387442AbgLBWLA (ORCPT ); Wed, 2 Dec 2020 17:11:00 -0500 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5FE4C061A48 for ; Wed, 2 Dec 2020 14:10:19 -0800 (PST) Received: by mail-pl1-x62a.google.com with SMTP id 4so1908563plk.5 for ; Wed, 02 Dec 2020 14:10:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=fx2J5kxkuy4RVQPdcQdvLIdfLQ1KmMIrt6Uak2OdX1I=; b=tZKIvjrSiwk2uFDis4sT08WCbufr0qyAwYTvUDg2a1MrjCtV/fmJ5/T8+sZeKg9D2N wJt+goPhJ113l0Fc3b+bMSWWKjMPk+WhmrAs2x9OuSt8SaSDlrfDY+6bhBmDAn2Iqljp +YIgHu+t69lJZPdcUjBFMqxsTF55uxqLHm6eqBGFvFbdgl82qI/jx/meEnEhM7Tk3wnD Su4/VypluEGAs/q2QZtRV0Uq1r4nGFGFdEFOAbzcPCwlXGbWQANIA4AiYHaGlz6QZjL5 vutp5wdVtQz459iI6e5yBRUmKKh7ChQj7BYG/tOAswb34eYxXcFhXNDE1r7OFRlUlT7J F4lA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=fx2J5kxkuy4RVQPdcQdvLIdfLQ1KmMIrt6Uak2OdX1I=; b=Qjy1AoPjm2CwKOi9h8iPMWsc9G91loF/UqIXOGQwH9Z8XAEI4NjNDvlNR/lgwPvIg3 7Gj9qZaHq5j+0sLwOA7fFj+JGLKXHQjBO4NZ9cd09dGUuSgBp8vQ/NdXNnMuwF85vQdN 3WtNQVqVlO39TGSAceDXI2Eaimyr9jdC5NqothoswWsbjP98eFP69JuqVJPWb2T6bUEP wHTwjUN2PW8Sz3Z99Zz7GzzxEUl8WLT9HcK5Li7UUNGeVijdVl1nH1ryUEaRj3+mGjDJ Tt6YkM2qoyuV9/vQIa3teI5eEXmWb9gUR/dWs28aEaOjn32kUxEnsMbXb2uWcisrIk3G rmHg== X-Gm-Message-State: AOAM533LWNY22u5M0qnJl/WrQhB0NWb+9oIftylMdVN0rtgQ9SZETpc+ 2wN+bXuC0ZaV06LSbJnTBOY= X-Google-Smtp-Source: ABdhPJw8knJBUKQ77DVvtCVmi2KSPYSuNH8GezOkQPNpENzO/6valQjY2xeJsZu62ZDOPXyS9QBOuw== X-Received: by 2002:a17:90a:fa8e:: with SMTP id cu14mr78855pjb.140.1606947019294; Wed, 02 Dec 2020 14:10:19 -0800 (PST) Received: from phantasmagoria.svl.corp.google.com ([2620:15c:2c4:201:f693:9fff:feea:f0b9]) by smtp.gmail.com with ESMTPSA id p16sm4872pju.47.2020.12.02.14.10.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Dec 2020 14:10:18 -0800 (PST) From: Arjun Roy To: davem@davemloft.net, netdev@vger.kernel.org Cc: arjunroy@google.com, edumazet@google.com, soheil@google.com Subject: [net-next v2 4/8] net-zerocopy: Refactor frag-is-remappable test. Date: Wed, 2 Dec 2020 14:09:41 -0800 Message-Id: <20201202220945.911116-5-arjunroy.kdev@gmail.com> X-Mailer: git-send-email 2.29.2.576.ga3fc446d84-goog In-Reply-To: <20201202220945.911116-1-arjunroy.kdev@gmail.com> References: <20201202220945.911116-1-arjunroy.kdev@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Arjun Roy Refactor frag-is-remappable test for tcp receive zerocopy. This is part of a patch set that introduces short-circuited hybrid copies for small receive operations, which results in roughly 33% fewer syscalls for small RPC scenarios. --- net/ipv4/tcp.c | 34 ++++++++++++++++++++++++++-------- 1 file changed, 26 insertions(+), 8 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 0f17b46c4c0c..4bdd4a358588 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1765,6 +1765,26 @@ static skb_frag_t *skb_advance_to_frag(struct sk_buff *skb, u32 offset_skb, return frag; } +static bool can_map_frag(const skb_frag_t *frag) +{ + return skb_frag_size(frag) == PAGE_SIZE && !skb_frag_off(frag); +} + +static int find_next_mappable_frag(const skb_frag_t *frag, + int remaining_in_skb) +{ + int offset = 0; + + if (likely(can_map_frag(frag))) + return 0; + + while (offset < remaining_in_skb && !can_map_frag(frag)) { + offset += skb_frag_size(frag); + ++frag; + } + return offset; +} + static int tcp_copy_straggler_data(struct tcp_zerocopy_receive *zc, struct sk_buff *skb, u32 copylen, u32 *offset, u32 *seq) @@ -1890,6 +1910,8 @@ static int tcp_zerocopy_receive(struct sock *sk, ret = 0; curr_addr = address; while (length + PAGE_SIZE <= zc->length) { + int mappable_offset; + if (zc->recv_skip_hint < PAGE_SIZE) { u32 offset_frag; @@ -1917,15 +1939,11 @@ static int tcp_zerocopy_receive(struct sock *sk, if (!frags || offset_frag) break; } - if (skb_frag_size(frags) != PAGE_SIZE || skb_frag_off(frags)) { - int remaining = zc->recv_skip_hint; - while (remaining && (skb_frag_size(frags) != PAGE_SIZE || - skb_frag_off(frags))) { - remaining -= skb_frag_size(frags); - frags++; - } - zc->recv_skip_hint -= remaining; + mappable_offset = find_next_mappable_frag(frags, + zc->recv_skip_hint); + if (mappable_offset) { + zc->recv_skip_hint = mappable_offset; break; } pages[pg_idx] = skb_frag_page(frags);