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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2433AC433E6 for ; Tue, 16 Mar 2021 22:50:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00F0064F3A for ; Tue, 16 Mar 2021 22:50:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231652AbhCPWti (ORCPT ); Tue, 16 Mar 2021 18:49:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231260AbhCPWtG (ORCPT ); Tue, 16 Mar 2021 18:49:06 -0400 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5489FC06174A; Tue, 16 Mar 2021 15:48:55 -0700 (PDT) Received: by mail-pf1-x432.google.com with SMTP id y13so9849661pfr.0; Tue, 16 Mar 2021 15:48:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HTHHLh0hTEeZauOlWKx3N6YCGdslyxRSMI7p5Hmw7jo=; b=CqLDhibfwjHh8p6Vd/+s2jfQeyE2Cx3eCSVa52SJZS6lGiC96C6E+neLRR9NXh5XDT 85xKcYe15dXRqs12u4LzZtaGV5n+9/OTH9ms5sAMYn94Euv5XD26Io3kFx7KffwF1ApY FAQrYQ/zD1XhPiTm9NqjNdNOTFefstir4bNpewHOMUnBJKhObZmu67CuxPHQqWKy8xcD Qjb8Yi4RKhIKQokeR0OSAuIUfgCakX7ZnDFiptHcNMrTBalbp/n2TYi2U19vdVE2V1YL AMOXW86NEgWuMZ7ukyOXJ+lMR0SBEbtWw/8tYhs8eAbWvsYmDN6IGCsmN/MiQ8Uz/EZr B0Sw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=HTHHLh0hTEeZauOlWKx3N6YCGdslyxRSMI7p5Hmw7jo=; b=SNzLlGhG6z16szYhMeJZTJhpsZ7VnYbJ/zkrN5ZUeVgagKBI4VqWLRsBHhQ1axyZoH qCMOGw+7nfFSqs/xUV/dRuPzHsB0r61oyJaa01fZdoNzzzFyttijaTK4EyysqMg8+4br naK9BSH1bXaEM3nusVvPXA7805l7hypLq0LwFXH80qcO4H+Ni1+xSVmkHj2qkOcO61Ej QRwlTbP9tT6kK1+MO/8hX054eSVHOjF6h19smh0vrfU/yzj+xLxZl+4oaF1ZTYdieex5 a5YZg8+UFH7nF6/H7+7exYGmGjBr/lEW1K5xxzZik+wSYE1kFXb2FJm2j/qkcuY/Ekbm 1FSw== X-Gm-Message-State: AOAM530Uki9xXEM3MCbup0V7jMprgItnvdKkxFQvLS3cNRC7jZRRdEko M47oBdAWHsDaMb7S0pVhJZw8sE599fRMEpZfUU8= X-Google-Smtp-Source: ABdhPJxDSD5FZtx9zrHIPa8F3AN4+4ja9E5BsIFXyJM1XP1lfiM/BWUKoVsp9mU2GPnfnKZfCy/UnkATaJp/I1zKcf4= X-Received: by 2002:a63:1266:: with SMTP id 38mr22409pgs.266.1615934934830; Tue, 16 Mar 2021 15:48:54 -0700 (PDT) MIME-Version: 1.0 References: <1615603667-22568-1-git-send-email-linyunsheng@huawei.com> <1615777818-13969-1-git-send-email-linyunsheng@huawei.com> <20210315115332.1647e92b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <20210315115332.1647e92b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> From: Cong Wang Date: Tue, 16 Mar 2021 15:48:43 -0700 Message-ID: Subject: Re: [RFC v2] net: sched: implement TCQ_F_CAN_BYPASS for lockless qdisc To: Jakub Kicinski Cc: Yunsheng Lin , David Miller , Vladimir Oltean , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eric Dumazet , Wei Wang , "Cong Wang ." , Taehee Yoo , Linux Kernel Network Developers , LKML , linuxarm@openeuler.org, Marc Kleine-Budde , linux-can@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 15, 2021 at 2:07 PM Jakub Kicinski wrote: > > I thought pfifo was supposed to be "lockless" and this change > re-introduces a lock between producer and consumer, no? It has never been truly lockless, it uses two spinlocks in the ring buffer implementation, and it introduced a q->seqlock recently, with this patch now we have priv->lock, 4 locks in total. So our "lockless" qdisc ends up having more locks than others. ;) I don't think we are going to a right direction... Thanks.