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=-3.6 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 0C70FC433E2 for ; Thu, 10 Sep 2020 20:19:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2E9F20882 for ; Thu, 10 Sep 2020 20:19:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PSjUzGam" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726781AbgIJUTZ (ORCPT ); Thu, 10 Sep 2020 16:19:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725791AbgIJUTN (ORCPT ); Thu, 10 Sep 2020 16:19:13 -0400 Received: from mail-io1-xd44.google.com (mail-io1-xd44.google.com [IPv6:2607:f8b0:4864:20::d44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E0FDC061573; Thu, 10 Sep 2020 13:19:13 -0700 (PDT) Received: by mail-io1-xd44.google.com with SMTP id d190so8635023iof.3; Thu, 10 Sep 2020 13:19:13 -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=s+AIzW9bZYd69ocgPt6/tPEsvQJmPkUuejY1VbCW5RI=; b=PSjUzGamK/yB5XyXSYNk6wk31Mk6jEgr5dlIwKKgp2yr8Iv5d4YrCEh6gMJADlZw1I HIM50Z1hOSNAyOrMjiQOj2EfvVQhKEeW/A14DV2yQN9X2drQ75sNjxCSkUuw2/5HxHC9 PL8zegiOF3qEJAMzKhvGuesj+HYq907JSiW2dBpOS1EjVwiz0Hvj9D9Wnamb6sOjPVmm sGk4+v9Oz32W3/7XFZGAvvW4bOerhzXUp+jgdhDnfH62epV9awNozdSfBCZ2laHfZBVF z9y62CmyQswHuAe2gNC8gOPsO0Ax98d5cg7rK7WVjrezok8Jj5PUrDmiadC+uenK1jTS OoLA== 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=s+AIzW9bZYd69ocgPt6/tPEsvQJmPkUuejY1VbCW5RI=; b=s06PllhQq89ukpiqL7nF6z/hkkFYADNGZnbsBSsHQB6u6vlAVkrTi1xEiMZSUQqJVf Yldvgz8LKngjTzf8Zvw8TVmIxdVkNhLXw8MSz8W8bnQ0cpS4HjZsOH/w1gOVQ7bnaNJz Vza8yhAtQO6fZH6YfDWyeGVjq6SwEMOr0pezFsWjb1y5PwRHdhtMw2QjjZd3btmzowmJ qElLKhZ8bzHk/bK9O5f9dh4BhKItPHJtblmMXtHANfY9ppSjp9j90Pj0Q3CMz3QOCxVS aJGYkP4mHSGB1YBBDH7i/Lw4ux6e/iZMcmW2wWsPkXDDfPNdkz+SZxCXuSoC20fNWEq7 KqTA== X-Gm-Message-State: AOAM5336s+yagZFURWhEpW7V+bKQF+l+/6jtPTj/2ROhwxeYhwIZyMTs bDgM4TdJAFcLm1g2IYkGlIyYvqknX7mvf1UDn9Y= X-Google-Smtp-Source: ABdhPJyK/kYoVACa8JXaGcMrn6ejBtf/33fdvZ0QxKmG40KQdhlSLaFv+zNVXZrYfTz1R6C2HS674CbsBqiHtDwdyus= X-Received: by 2002:a6b:da19:: with SMTP id x25mr8978079iob.12.1599769152687; Thu, 10 Sep 2020 13:19:12 -0700 (PDT) MIME-Version: 1.0 References: <465a540e-5296-32e7-f6a6-79942dfe2618@netrounds.com> <20200623134259.8197-1-mzhivich@akamai.com> <1849b74f-163c-8cfa-baa5-f653159fefd4@akamai.com> <7fd86d97-6785-0b5f-1e95-92bc1da9df35@netrounds.com> <500b4843cb7c425ea5449fe199095edd5f7feb0c.camel@redhat.com> <25ca46e4-a8c1-1c88-d6a9-603289ff44c3@akamai.com> <20200822032800.16296-1-hdanton@sina.com> <20200825032312.11776-1-hdanton@sina.com> <20200825162329.11292-1-hdanton@sina.com> <5f46032e.1c69fb81.9880c.7a6cSMTPIN_ADDED_MISSING@mx.google.com> <20200827125747.5816-1-hdanton@sina.com> <20200903101957.428-1-hdanton@sina.com> In-Reply-To: From: Cong Wang Date: Thu, 10 Sep 2020 13:19:01 -0700 Message-ID: Subject: Re: Packet gets stuck in NOLOCK pfifo_fast qdisc To: Kehuan Feng Cc: Hillf Danton , Paolo Abeni , Jike Song , Josh Hunt , Jonas Bonn , Michael Zhivich , David Miller , John Fastabend , LKML , Netdev Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Sep 3, 2020 at 8:21 PM Kehuan Feng wrote: > I also tried Cong's patch (shown below on my tree) and it could avoid > the issue (stressing for 30 minutus for three times and not jitter > observed). Thanks for verifying it! > > --- ./include/net/sch_generic.h.orig 2020-08-21 15:13:51.787952710 +0800 > +++ ./include/net/sch_generic.h 2020-09-03 21:36:11.468383738 +0800 > @@ -127,8 +127,7 @@ > static inline bool qdisc_run_begin(struct Qdisc *qdisc) > { > if (qdisc->flags & TCQ_F_NOLOCK) { > - if (!spin_trylock(&qdisc->seqlock)) > - return false; > + spin_lock(&qdisc->seqlock); > } else if (qdisc_is_running(qdisc)) { > return false; > } > > I am not actually know what you are discussing above. It seems to me > that Cong's patch is similar as disabling lockless feature. >From performance's perspective, yeah. Did you see any performance downgrade with my patch applied? It would be great if you can compare it with removing NOLOCK. And if the performance is as bad as no NOLOCK, then we can remove the NOLOCK bit for pfifo_fast, at least for now. Thanks.