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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 69FF5C2D0BF for ; Sat, 14 Dec 2019 01:59:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56A0A214AF for ; Sat, 14 Dec 2019 01:59:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="VxYFXFAm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726767AbfLNB76 (ORCPT ); Fri, 13 Dec 2019 20:59:58 -0500 Received: from mail-pj1-f67.google.com ([209.85.216.67]:37390 "EHLO mail-pj1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726046AbfLNB75 (ORCPT ); Fri, 13 Dec 2019 20:59:57 -0500 Received: by mail-pj1-f67.google.com with SMTP id ep17so479384pjb.4; Fri, 13 Dec 2019 17:59:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=LxNQ93N0kzZYFokT7bl3z1w7v0WAye//I7zpGer0E8s=; b=VxYFXFAmZAHGDCOJ3wSwm/jC1vdG/ArsWrqdALacCEtvdbE5xdIaTmueBXmX1vgMVx y4VYLmEQfnWBqF/1WPnWeh+fdojnsAJqfmUzj2w6nvy2L7D/PSpVMkSuFvq4Kz5jvYWO HtWqpkpuSCw6OMVCgUCSkEsAizj8X+4nk7FztPs1VuEWjRpjVDljQ0CPbBP1QJHLq5H9 Cf4f8C21yL/+M8Q3Q+xXFMtGpSjG58ROda3OlO8Vg+UQL3zRLjP8Ki2wfP0MVQHDvXk/ POlu/nYRKW/FXhDqy9tjPTfR9/3jN+efcf30crcBPXTiGGAVG7UO5tRyhB+7bDj1V1Xm vfxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=LxNQ93N0kzZYFokT7bl3z1w7v0WAye//I7zpGer0E8s=; b=KcWOzSA+W1Qyeu/XNigahAeS7xhxgMajAhkZdHNsWi97oGof58guatXVj3ddJl4EpM O7h0CWV4BSOBP64A5S0eQF8IRz2H7wdwHABQeSIORF4zmuxdH+LZCPfLqbxpTyEm7QZg ZZMPBlgqSHFuZXOlFj62yglmamHGmk5NtrmORXiBHGqNQa4aNen+/atYRbMBSv1FtDuf f6BLhtXU3YQ238D00t3PicjxmBWHdXhuxEwfhkrQdtyGwZYrm3DucJZQMd606dAZnp+I mhSWe6iKW4JBlXC0LJJMr6R7RQGZG7XsAev48KrdZKXt5mGFlUJ6dLBkQXvMD7uqygTy hKpw== X-Gm-Message-State: APjAAAWv1R8ROAmdg2wDtT5O6/i8XSIZzLPDPr44b4zVrAvc47iskxom 8Oqz+SY6oMRD6FK5Zm+5sVpis0aG X-Google-Smtp-Source: APXvYqzTgdBq2WJRmx15b0V06YvyK3H4fOGH1sDPHA+p2USbqoxw30H1cKx95Gp+1FzolDAH1SUg8g== X-Received: by 2002:a17:90a:9c1:: with SMTP id 59mr3044962pjo.65.1576288795960; Fri, 13 Dec 2019 17:59:55 -0800 (PST) Received: from [192.168.86.235] (c-73-241-150-58.hsd1.ca.comcast.net. [73.241.150.58]) by smtp.gmail.com with ESMTPSA id j14sm12152148pgs.57.2019.12.13.17.59.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Dec 2019 17:59:55 -0800 (PST) Subject: Re: [PATCH bpf-next 09/13] bpf: Add BPF_FUNC_jiffies To: Martin KaFai Lau , bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , David Miller , kernel-team@fb.com, netdev@vger.kernel.org References: <20191214004737.1652076-1-kafai@fb.com> <20191214004758.1653342-1-kafai@fb.com> From: Eric Dumazet Message-ID: Date: Fri, 13 Dec 2019 17:59:54 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191214004758.1653342-1-kafai@fb.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 12/13/19 4:47 PM, Martin KaFai Lau wrote: > This patch adds a helper to handle jiffies. Some of the > tcp_sock's timing is stored in jiffies. Although things > could be deduced by CONFIG_HZ, having an easy way to get > jiffies will make the later bpf-tcp-cc implementation easier. > ... > + > +BPF_CALL_2(bpf_jiffies, u64, in, u64, flags) > +{ > + if (!flags) > + return get_jiffies_64(); > + > + if (flags & BPF_F_NS_TO_JIFFIES) { > + return nsecs_to_jiffies(in); > + } else if (flags & BPF_F_JIFFIES_TO_NS) { > + if (!in) > + in = get_jiffies_64(); > + return jiffies_to_nsecs(in); > + } > + > + return 0; > +} This looks a bit convoluted :) Note that we could possibly change net/ipv4/tcp_cubic.c to no longer use jiffies at all. We have in tp->tcp_mstamp an accurate timestamp (in usec) that can be converted to ms. Have you thought of finding a way to not duplicate the code for cubic and dctcp, maybe by including a template ? Maintaining two copies means that future changes need more maintenance work.